Patent Publication Number: US-2022233065-A1

Title: Physical assessment device with coordinated led drive circuit for image capture

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 63/258,226, filed Apr. 19, 2021, and is a continuation in part of U.S. patent application Ser. No. 17/483,347, filed Sep. 23, 2021, which is a continuation of U.S. patent application Ser. No. 16/248,482 (now U.S. Pat. No. 11,147,441), issued Oct. 19, 2021, which claims priority to U.S. Provisional Patent Application No. 62/617,929, filed Jan. 16, 2018, each of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     This application is generally directed to the field of diagnostic medicine and more specifically to an improved physical assessment device, (e.g., an otoscope or ophthalmoscope), which is configured for performing diagnostic patient examinations. 
     BACKGROUND 
     Physical assessment devices are well known in the field of diagnostic medicine for examining patients as part of wellness visits and/or routine examinations. These devices include, among others, otoscopes for diagnosing conditions of the ear, ophthalmoscopes for diagnosing conditions associated with the eye of a patient, and dermatoscopes for examining the skin of a patient. Each of these physical assessment devices typically includes an instrument head that is releasably attached to the upper end of an instrument handle, the latter containing a set of batteries, enabling the devices to be compact and capable of being handled with one hand. The instrument head can retain optics that enable an image of a medical target (e.g., ear, eye) to be viewed by a caregiver through an eyepiece, or alternatively the image of the medical target can be transmitted to an electronic imager associated with the physical assessment device. Suitable illumination of the medical target of interest is provided by a resident light source, such as an incandescent lamp. Incandescent lamps may be dimmed using known techniques, so that the medical target will be illuminated with the appropriate contrast for visibility. The electronic imager may be used to capture an image of the medical target for later use by the caregiver or other medical professional. 
     There is a general need in the field of diagnostic medicine to improve physical assessment devices, such those described above. 
     BRIEF DESCRIPTION 
     According to one aspect, there is provided a physical assessment device. The physical assessment device includes an instrument head, an optical assembly and an adapter interface member. The instrument head has a distal end, an opposing proximal end and an interior. The instrument head includes an illumination assembly including at least one LED and a drive circuit for powering the at least one LED with a pulse width modulation (PWM) current to achieve a variable brightness of the at least one LED. The optical assembly is disposed within the instrument head and includes a plurality of optical components disposed along an optical axis. The adapter interface member is disposed at the proximal end of the instrument head, and enables an image capture device to be attached to the instrument head and aligned with the optical axis. The image capture device is configured to capture images of medical targets when illuminated by the at least one LED with the variable brightness. The drive circuit is coordinated with the image capture device to ensure that the medical targets are at least partially illuminated during the capturing of the images notwithstanding the variable brightness of the at least one LED being achieved using the PWM current. 
     In one aspect, the drive circuit is coordinated with the image capture device to ensure that the medical targets are at least partially illuminated during the capturing of the images by selecting a frequency of a duty cycle of the drive circuit to include at least two on-cycles of the PWM current to overlap with an image scanning period of the image capture device. 
     In another aspect, the drive circuit is coordinated with the image capture device to ensure that the medical targets are at least partially illuminated during the capturing of the images by selecting the drive circuit to output a substantially triangle wave current with a minimum current value greater than zero. 
     One advantage realized by the herein described physical assessment device is that a imaging device, such as that included in a smart phone, can be mechanically and optically coupled to a device, such as an otoscope or ophthalmoscope, which is typically only configured for optical viewing by a caregiver. When so coupled, a medical target may be illuminated with an appropriate brightness of an LED light of the assessment device and an image may be captured by the smart device, such that the image is free of defects and artifacts (or has a reduced amount of defects and artifacts) that would otherwise impede use of the image by a caregiver or other medical professional. 
     These and other features and advantages will be apparent from the following Detailed Description, which should be read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1( a )  is a side elevational view of a physical assessment device made in accordance with an embodiment; 
         FIG. 1( b )  is a front perspective view of the physical assessment device of  FIG. 1( a ) ; 
         FIG. 2( a )  is a side elevational view of the instrument head of the physical assessment device of  FIGS. 1( a ) and 1( b ) ; 
         FIG. 2( b )  is a side view taken in section, of the instrument head of  FIGS. 1( a )-2( a ) ; 
         FIG. 2( c )  is a rear facing view of the instrument head of  FIGS. 1( a )-2( b ) ; 
         FIG. 2( d )  is a rear perspective view of the instrument head of  FIGS. 1( a )-2( c ) ; 
         FIG. 2( e )  is a another rear perspective view of the instrument head of  FIGS. 1( a )-2( d ) ; 
         FIG. 2( f )  is a side perspective view of the instrument head of  FIGS. 1( a )-2( e ) ; 
         FIG. 2( g )  is another side perspective view of the instrument head of  FIGS. 1( a )-2( f ) ; 
         FIG. 2( h )  is a bottom plan view of the instrument head of  FIGS. 1( a )-2( g ) ; 
         FIG. 2( i )  is a top plan view of the instrument head of  FIGS. 1( a )-2( h ) ; 
         FIG. 2( j )  is a left side elevation view of the instrument head of  FIGS. 1( a )-2( i ) ; 
         FIG. 2( k )  is a right side elevation view of the instrument head of  FIGS. 1( a )-2( j ) ; 
         FIG. 3  is an exploded assembly view of the instrument head shown in  FIG. 1( a ) - FIG. 2( k ) ; 
         FIG. 4  is an exploded view of a lens tube fitted within the instrument head of  FIGS. 1( a ) - FIG. 3 ; 
         FIG. 5( a )  is a side perspective view of an instrument head in accordance with an alternative embodiment; 
         FIG. 5( b )  is a side view, taken in section, of the instrument head of  FIG. 5( a ) ; 
         FIGS. 6 and 7  are exploded assembly views of a smart device adapter made in accordance with an exemplary embodiment; 
         FIG. 8( a )  is a front facing view of the smart device adapter of  FIGS. 6 and 7 ; 
         FIG. 8( b )  is a sectioned view of the adapter taken through line  8 - 8  of  FIG. 8( a ) ; 
         FIG. 9( a )  is a rear facing view of the smart device adapter of  FIGS. 8( a ) and 8( b ) ; 
         FIG. 9( b )  is a side sectioned view of the smart device adapter taken through section lines  9 - 9  of  FIG. 9( a ) ; 
         FIGS. 10( a )-10( e )  are views depicting a sequential assembly flow of the smart device adapter of  FIGS. 6-9 ( b ); 
         FIG. 11( a )  is a partially broken away view of a smart device adapter having an attached device engagement member; 
         FIG. 11( b )  is a partial rear perspective view of the smart device adapter of  FIGS. 6-11 ( a ); 
         FIG. 11( c )  is a left side elevation view of the smart device adapter of  FIGS. 6-11 ( b ); 
         FIG. 11( d )  is a right side elevation view of the smart device adapter of  FIGS. 6-11 ( c ); 
         FIG. 11( e )  is a front view of the smart device adapter of  FIGS. 6-11 ( d ); 
         FIG. 11( f )  is a rear view of the smart device adapter of  FIGS. 6-11 ( e ); 
         FIG. 11( g )  is a top plan view of the smart device adapter of  FIGS. 6-11 ( f ); 
         FIG. 11( h )  is a bottom plan view of the smart device adapter of  FIGS. 6-11 ( g ); 
         FIG. 11( i )  is a front perspective view of the smart device adapter of  FIGS. 6-11 ( h ); 
         FIG. 11( j )  is a bottom perspective view of the smart device adapter of  FIGS. 6-11 ( i ); 
         FIG. 11( k )  is a rear perspective view of the smart device adapter of  FIGS. 6-11 ( j ); 
         FIG. 11( l )  is another bottom view of the smart device adapter of  FIGS. 6-11 ( k ); 
         FIG. 12( a )  is a left side view of a device engagement member in accordance with an embodiment; 
         FIG. 12( b )  is a front view of the device engagement member of  FIG. 12( a ) ; 
         FIG. 12( c )  is a rear facing view of the device engagement member of  FIGS. 12( a ) and 12( b ) ; 
         FIG. 12( d )  is a top plan view of the device engagement member of  FIGS. 12( a )-12( c ) ; 
         FIG. 12( e )  is a bottom view of the device engagement member of  FIGS. 12( a )-12( d ) ; 
         FIG. 12( f )  is a front perspective view of the device engagement member of  FIGS. 12( a )-12( e ) ; 
         FIG. 12( g )  is a rear perspective view of the device engagement member of  FIGS. 12( a )-12( f ) ; 
         FIG. 12( h )  is another rear perspective view of the device engagement member of  FIGS. 12( a )-12( g ) ; 
         FIG. 13( a )  is a partial side view, taken in section, of the smart device adapter of  FIGS. 6-11 ( l ) and device engagement member of  FIGS. 12( a )-12( h ) , as assembled to the physical assessment device of  FIGS. 1( a ) - 5 ; 
         FIG. 13( b )  is the side sectioned view of the instrument head of  FIGS. 2( b )-2( k ) , smart device adapter of  FIGS. 6-11 ( l ) and device engagement member of  FIGS. 12( a )-12( h ) , further depicting a ray trace of the optical system or assembly including a distal entrance pupil produced by the optical system; 
         FIG. 14  is a partially assembled rear perspective view of a known physical assessment device having a smart device adapter made in accordance with another embodiment; 
         FIG. 15  is an exploded assembly view of the smart device adapter of  FIG. 14 ; 
         FIG. 16  is a front perspective view of the physical assessment device of  FIG. 14  as assembled with the smart device adapter of  FIG. 15  prior to a smart device being releasably attached; 
         FIG. 17  depicts a prior art physical assessment device (on the left) with the physical assessment device of  FIGS. 1-5 ( b ) as shown in side by side relation; 
         FIG. 18  is a side perspective view of the prior art physical assessment device having an attached smart device adapter, which is made in accordance with another embodiment; 
         FIG. 19  is another perspective view of the prior art physical assessment device and smart device adapter of  FIG. 18 ; 
         FIG. 20  is a front perspective view of the smart device adapter of  FIGS. 18 and 19 ; 
         FIG. 21  is a perspective view of a physical assessment device made in accordance with another embodiment; 
         FIG. 22  is a perspective view of a physical assessment device made in accordance with yet another embodiment; 
         FIG. 23  is a rear perspective view of the instrument head of the physical assessment device of  FIG. 21 ; 
         FIG. 24( a )  is a perspective view of the instrument head of the physical assessment device of  FIG. 22 ; 
         FIG. 24( b )  is a rear perspective view of the instrument head of  FIG. 24( a ) , including an attached smart device; 
         FIGS. 25( a ), 25( c ) and 25( d )  are partial assembly views and  FIG. 25( b )  is an assembled view of the instrument head of  FIGS. 21 and 23 ; 
         FIGS. 26( a ) and 26( b )  are partially assembled and assembled views of the instrument head of  FIGS. 22 and 24 ( a ); 
         FIG. 27  is a sectioned elevational view of the instrument head of  FIGS. 21, 23 and 25 ( a )- 25 ( d ); 
         FIG. 28  is a sectioned elevational view of the instrument head of  FIGS. 22, 24 ( a ) and  26 ( a ) and  26 ( b ); 
         FIG. 29  is a perspective view of an instrument head for a physical assessment device made in accordance with another embodiment; 
         FIG. 30  is a perspective view of an instrument head for a physical assessment device in accordance with yet another embodiment; 
         FIG. 31  is a perspective of an intermediate assembly strap used in the instrument heads of  FIGS. 29 and 30 ; 
         FIG. 32  is a sectioned partial view of the bottom of an instrument head depicting the securement of the intermediate assembly strap of  FIG. 31  to an instrument head; 
         FIG. 33  is a sectioned partial view of an instrument head of a physical assessment device in accordance with an embodiment; 
         FIG. 34  is an enlarged sectioned view of a portion of the instrument head of  FIG. 33 , including an integrated component of the illumination assembly used for centering a contained LED and collimating light emitted from the LED; 
         FIG. 35  is a partially cutaway top perspective view depicting the integrated component of  FIG. 34  within the instrument head relative to the retained LED; 
         FIG. 36  is a top perspective view of the integrated component of  FIGS. 34 and 35 ; 
         FIG. 37  is an side elevational view in section of the physical assessment device of  FIG. 21 ; 
         FIG. 38  is an enlarged elevational view of the top of an instrument handle of a physical assessment device in accordance with an embodiment; 
         FIG. 39  is a bottom perspective view of an instrument head configured to engage the instrument handle of  FIG. 38 ; 
         FIG. 40  is an enlarged portion of the instrument head of  FIG. 39 ; 
         FIG. 41  is a partial sectioned view of the physical assessment device of  FIG. 37 , depicting the engagement between the instrument head and instrument handle; 
         FIG. 42  is an enlarged view of a portion of  FIG. 41 ; 
         FIG. 43  is an enlarged portion of the instrument handle of  FIG. 38 ; 
         FIG. 44  is an elevational view of an instrument handle for a physical assessment device in accordance with an embodiment; 
         FIG. 45  is a sectioned partial view of the top of the instrument handle of  FIGS. 37 and 38 ; 
         FIG. 46  is a partial sectioned view of the instrument handle of  FIGS. 37 and 45 , depicting aspects of a rheostat assembly in accordance with an embodiment; 
         FIG. 47  is a perspective view of a detent ring member of the rheostat assembly of  FIG. 46 ; 
         FIG. 48  is a perspective view of an instrument handle made in accordance with another embodiment; 
         FIG. 49  is a partial sectioned view of the instrument handle of  FIG. 48 , depicting a USB charging port; 
         FIG. 50  is a sectioned view of the instrument handle of  FIGS. 48 and 49 , illustrating battery charging contacts; 
         FIG. 51  is the sectioned view of  FIG. 50 , illustrating the engagement of the instrument handle with a charging base or cradle; 
         FIG. 52  is a perspective view of a charging base or cradle having a pair of physical assessment devices attached thereto; 
         FIG. 53  is a sectioned view of an instrument handle including a feature for detecting overheating of a contained battery; 
         FIG. 54( a )  presents an optical layout of the physical assessment device of  FIG. 13( b ) ; 
         FIG. 54( b )  depicts a comparison of layouts between an optical assembly of a known physical assessment device with other versions in accordance with various embodiments of the invention; 
         FIG. 55  illustrates the advantageous effect of the inventive optical assemblies of  FIGS. 54( a ) and 54( b )  relative to an attached accessory of the physical assessment device, as compared to an existing optical assembly; 
         FIG. 56  is a layout of an alternative optical system, which is defined having glass components in lieu of plastically molded components; 
         FIGS. 57( a ) and 57( b )  are side perspective views of a physical assessment device made in accordance with another embodiment; 
         FIG. 58  is an exploded view of the instrument head of the physical assessment device of  FIGS. 57( a ) and 57( b ) ; 
         FIG. 59( a )  is a side elevation view in section of the instrument head of  FIG. 58 , further depicting a ray trace of a contained optical assembly; 
         FIG. 59( b )  is the side elevation view in section of the instrument head of  FIG. 59( a ) , further depicting a ray trace of a contained illumination assembly; 
         FIG. 60( a )-60( d )  are various views of an adjustable mirror mount assembly of the instrument head of  FIGS. 58-59 ( b ); 
         FIG. 61  is a side elevational view of a physical assessment device made in accordance with another embodiment; 
         FIG. 62  is a partial front perspective view of a physical assessment device having an attached smart device; 
         FIG. 63  is a front perspective view of an instrument head of the physical assessment device of  FIG. 62 , including an attached eye cup; 
         FIGS. 64( a ) and 64( b )  are side elevation view, one in section of the eye cup of  FIG. 63  having a disposable ring member in accordance with an embodiment; 
         FIG. 65  is a sectioned view of the instrument head of a physical assessment device in accordance with another embodiment; 
         FIG. 66  is an overall schematic view of the optical and illumination assemblies of the physical assessment device of  FIG. 65 ; 
         FIG. 67  is a ray trace diagram of the illumination assembly of the physical assessment device of  FIGS. 65 and 66 ; 
         FIG. 68  is a ray trace diagram of the optical assembly of the physical assessment device of  FIGS. 65-67 ; 
         FIG. 69  is a front view of the distal end of the instrument head of  FIG. 65 , depicting a pair of spaced fixation target illuminators; 
         FIG. 70  is an enlarged sectioned view of the lower portion of the instrument head of  FIG. 65 ; 
         FIG. 71( a )  is an enlarged sectioned view of a portion of  FIG. 65 ; 
         FIG. 71( b )  is a perspective view of the mirror support member of  FIG. 71( a ) ; 
         FIGS. 72( a ) and 72( b )  are partial perspective views, partially in section, of a portion of the optical assembly, including the rotatable diopter wheel of the instrument head of  FIGS. 65-67 ; 
         FIG. 73  depicts a comparative layout of a pair of optical assemblies for a physical assessment device; 
         FIG. 74  illustrates physical assessment devices having the optical assemblies illustrated in  FIG. 73 ; 
         FIG. 75  illustrates various ray traces of an illumination assembly according to an embodiment as compared to an existing illumination assembly; 
         FIGS. 76( a ) and 76( b )  depict instrument heads typically used for ophthalmic examinations in which the instrument heads can be configured for otological examinations in accordance with exemplary embodiments; 
         FIG. 77  is a block diagram of a circuit for controlling LED lighting in an instrument head in accordance with an embodiment; 
         FIG. 78  is a flowchart depicting a method for controlling LED lighting in an instrument head in accordance with an embodiment; 
         FIG. 79  is a circuit diagram of the controller of  FIG. 77 ; 
         FIG. 80  is a circuit diagram of the power conversion circuit of  FIG. 77 ; 
         FIG. 81  is a circuit diagram of the FET full-wave bridge circuit of  FIG. 77 ; 
         FIG. 82  illustrates an electrical circuit diagram of a field-effect transistor (FET) rectifier/bridge in accordance with another exemplary embodiment; 
         FIGS. 83( a ) and 83( b )  illustrates a diagram of an LED drive circuit in accordance with another exemplary embodiment; 
         FIG. 84  illustrates an electrical circuit in accordance with another embodiment enabling an instrument handle to be charged using a charging base or via USB; 
         FIGS. 85( a ) and 85( b )  are diagrams of circuits that will drive both an LED and halogen based lamp from a single varying power source and maintain loop stability so that there is no risk of blinking LEDs; 
         FIG. 86  is a schematic diagram of a voltage boost circuit made in accordance with an embodiment; 
         FIG. 87  depicts PWM dimming of an LED light; 
         FIGS. 88A-88B  depict an images of medical targets with artifacts, when using PWM dimming; 
         FIG. 89  depicts one example of a drive circuit for capturing images of medical targets free of artifacts in accordance with an embodiment; 
         FIG. 90  depicts another example of a drive circuit for capturing images of medical targets free of artifacts in accordance with an embodiment; 
         FIG. 91  depicts a substantially triangle wave current produced by the drive circuit of  FIGS. 90 ; and 
         FIG. 92  depicts an example of capturing an image of medical target free of artifacts in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following relates to various embodiments of physical assessment devices that are typically used for examining a patient, and more specifically otoscopes typically used for examining the ears of a patient and ophthalmoscopes typically used for examining the eyes of a patient. It will be readily apparent to the reader from the description that follows that a number of the herein described features can be incorporated into physical assessment devices other than those being described. In addition, a number of the inventive features described are not confined to any specific embodiment and are equally applicable to other described embodiments/devices. In addition, a number of terms are used throughout the following description for purposes of providing a suitable frame of reference in regard to the accompanying drawings. These terms, which include “first”, “second”, “upper”, “lower”, “left”, “right”, “above”, “below”, “distal”, “proximal”, “interior”, “exterior”, “internal” and “external”, among others, are not intended to limit any of the described inventive aspects, except where so specifically and conspicuously indicated. In addition and for purposes of clarity, like reference numerals are used throughout the discussion of each of the various embodiments. 
     In addition, the drawings provided are intended to show salient features of the herein described physical assessment devices. The drawings, however, are not intended to provide scalar relationships between any of the various depicted components unless specified to the contrary. 
     Otoscope 
     A first physical assessment device (otoscope) is described.  FIGS. 1( a ) and 1( b )  depict a side view and a front perspective view of the physical assessment device, respectively, which according to this embodiment is an otoscope  100 . The otoscope  100  is designed primarily for performing diagnostic examinations of the ear of a patient, although the herein described physical assessment device  100  can also be used for examining other anatomical cavities (i.e., the nose, throat) of a patient. The otoscope  100  is defined by an instrument head  104  that is releasably attached to the upper end of an instrument handle or handle portion  108 . The instrument handle  108  is sized and shaped to permit the otoscope  100  to be handheld and is further configured to retain at least one battery (not shown in these views) for powering a light source (not shown) contained in the instrument head  104 . The contained light source is energized by an on-off button  118  disposed on the exterior of the handle portion  108 , wherein the illumination output of the contained light source can be controlled using a rheostat  117 , the latter including a twistable portion formed on the handle portion  108 . The contained battery can preferably be recharged via a charging port  119 , which is provided in the bottom end of the handle portion  108 . 
     As shown in  FIG. 2( a ) , the instrument head  104  according to this embodiment is defined by a body or housing having a distal or patient end  112  and an opposing proximal or caregiver end  116 . A hollow speculum tip element  120  is releasably attached to the distal end  112  of the instrument head  104 , the speculum tip element  120  being designed and shaped to fit a predetermined distance into the ear canal while the proximal end  116  of the instrument head  104  includes an adapter interface member  180 . 
     The interior of the instrument head  104  is essentially hollow and sized and configured to retain a plurality of components. With reference to  FIGS. 2( a )-2( k )  and  3  and according to this exemplary embodiment, the instrument head  104  includes a pair of mated housing sections; specifically a front housing section  130  and a rear housing section  134 . Each housing section  130 ,  134  is a shell-like member made from a structural material, such as a moldable plastic. Each of the housing sections  130 ,  134  are mated to one another according to this embodiment using fasteners  136 ,  FIG. 3 , to define an interior cavity. Alternatively, the housing sections  130 ,  134  can also be secured by welding, such as ultrasonic welding or other suitable means. As discussed in greater detail in a later portion of this description, the lower ends  131 ,  135  of each of the housing sections  130 ,  134  are retained at the bottom of the instrument head  104  using a securing ring  280 . According to this embodiment, a peripheral bumper  137  is disposed between the front and rear housing sections  130 ,  134 . An innerformer  138  disposed within the interior of the front housing section  130  includes a conical distal portion  139 , as well as a lower portion  141 . The innerformer  138  is essentially hollow and defines an interior cavity of the instrument head  104  to enable insufflation via a port connector (not shown) extending outwardly to a corresponding access opening  114 ,  FIG. 1( b ) , formed in the front housing section  130 . 
     With reference to  FIGS. 2( b ) - 4 , the herein described otoscope  100  retains an optical assembly that includes a hollow lens tube  152  containing a plurality of optical components is supported within the interior of the instrument head  104  and more specifically within the innerformer  138 . The lens tube  152  is defined by opposing distal and proximal ends  154 ,  156 , respectively. An objective lens  160  is fitted within the distal end  154  of the lens tube  152  adjacent an optical window  161  that covers the distal end  154  of the lens tube  152 . A cylindrical hollow spacer  163  is provided proximally of the objective lens  160  along with a relay lens  166 , each of the spacer  163  and relay lens  166  being disposed within an intermediate axial portion  155  of the lens tube  152 . The diameter of the lens tube  152  further widens at its proximal end  156 , which retains an imaging lens  169  disposed in relation to a field stop  170  with a coiled spring  172  being disposed therebetween. A threaded retaining cap  175  at the proximal end  156  of the lens tube  152  maintains pressure against the imaging lens  169 . In addition, a field stop  164  is disposed within the lens tube  152  between the window  161  and objective lens  160  to reduce light scatter and an aperture plate  167  is disposed within the lens tube  152  proximal to the relay lens  166 . 
     As shown in  FIGS. 2( b ) ,  3  and  4 , the proximal threaded portion  157  of the hollow lens tube  152  engages a set of corresponding internal threads formed on a distal portion of the adapter interface member  180 . The adapter interface member  180  is a substantially cylindrical section according to this embodiment having its distal portion  182  extending into the proximal end  116  of the instrument head  104  and further including an outwardly extending proximal portion  188 . A recess  184  defined between the distal and proximal portions  182 ,  188  of the adapter interface member  180  is sized and configured to receive a smart device adapter  300 , partially shown in  FIG. 5 . The recess  184 , is substantially annular with the inclusion of a series of machined flats  186 ,  FIG. 2( a )  and  FIGS. 2( d )-2( k ) . According to this embodiment, four (4) flats  186  are provided, although the specific number can be suitably varied. Further details relating to the smart device adapter  300  are described in greater detail in a subsequent section of this application. 
     When assembled, the distal end  154  of the hollow lens tube  152  is positioned at the distal end  112  of the instrument head  104  with the opposing proximal end  156  of the lens tube  152  extending from an opening formed in the innerformer  138 . The adapter interface member  180  is threadingly engaged with the proximal end  156  of the hollow lens tube  152  and extends outwardly from an opening formed in the rear housing section  134  of the instrument head  104 . 
     A series of circumferentially spaced axial openings  183  are provided within the distal portion  182  of the adapter interface member  180 . Each axial opening  183 , which extends into the defined recess  184 , receives a coiled compression spring  185  as well as a ball  187 , the latter extending partially into the recess  184  to provide positive engagement with a smart device adapter  300 , when the latter is attached. An intermediate plate  190  is positioned onto the exterior of the proximal end  156  of the lens tube  152  distally relative to the threaded portion of the lens tube  152  and in contact with a sealing member  142 . According to this embodiment, the adapter interface member  180  is further defined by an interior that includes an optical window  189  secured within the outwardly extending proximal portion  188 . A brow rest or cap  194  covers the extending proximal portion  188  of the adapter interface member  180 . 
     The sealing member  142  is made from an elastomeric material and disposed at the proximal end of the innerformer  138  on a formed annular shoulder. When assembled, the sealing member  142  is further engaged against the intermediate plate  190  and the adapter interface member  180  to provide adequate sealing within the innerformer  138  to enable insufflation of a patient. 
     With further reference to  FIGS. 2( b )  and  3 , the distal end  154  of the hollow lens tube  152  extends through the distal insertion portion  140  such that the optical window  161  and adjacent objective lens  160  are disposed at the distal end  154  of the distal insertion portion  140 . As previously discussed, a speculum tip element  120  is releasably attached to the distal end  112  of the instrument head  104 . According to this embodiment, the speculum tip element  120  is a hollow member made from a lightweight molded plastic material defined by a truncated frusto-conical shape having a distal tip opening  124  and an opposing proximal tip opening  128 . The exterior surface of the speculum tip element  120  at its proximal end includes at least one engagement feature that enables the speculum tip element  120  to be releasably attached to the distal end  112  of the instrument head  104 . According to this specific version, a total of three (3) engagement features are provided, each engagement feature including a ramped surface having a series of closely spaced engagement teeth. 
     The speculum tip element  120  is disposed in overlaying relation onto a distal insertion portion  140 , the latter being defined by a substantially conical surface that is disposed in overlaying relation onto the conical distal portion  139  of the innerformer  138 . According to this exemplary amendment, the innerformer  138  can include at least one exterior feature shaped and configured for engaging and retaining the distal insertion portion  140 . The speculum tip element  120  is releasably secured to a distal ring member  146 , the latter being disposed within the distal end of the front housing section  130  with the distal insertion portion  140  extending distally outward of the distal ring member  146 . 
     The distal ring member  146 , which is disposed relative to the front housing section  130  includes a number of engagement features that are configured to permit releasable attachment of the speculum tip element  120 . More specifically, the distal ring member  146  includes a plurality of ramped surfaces formed at circumferentially spaced locations, each ramped surface being shaped and configured to engage the exterior engagement features of the speculum tip member  120 . According to this embodiment, the distal ring member  146  is configured to receive one of a plurality of speculum tip elements  120 , including those having instrumentation, each tip element  120  having exterior engagement features that engage with the ramped surfaces of the distal ring member  146 . 
     The speculum tip element  120  is mounted onto the distal insertion portion  140  with the exterior engagement features of the speculum tip element  120  being engaged by the ramped surfaces provided on the distal ring member  146 . The speculum tip element  120  is secured and released by means of an appropriate twisting motion. As noted and when attached, the speculum tip element  120  is designed to be fitted up to a predetermined distance into the ear canal of the patient. 
     The foregoing components combine to define the optical assembly for the herein described otoscope  100 . As described in later portions of this application, a smart device adapter can be attached to the adapter interface member  180  to enable a smart device (e.g., a smart phone) to be attached to the instrument head  104  and enable images of the ear canal and more specifically the tympanic membrane to be captured. 
     An alternative version of an otoscopic instrument head  104 A is shown in  FIGS. 5( a ) and 5( b ) . Similar parts are labeled with the same reference numerals for the sake of clarity. This instrument head  104 A according to this embodiment includes the front housing portion  130 , a rear housing portion  134 A and an innerformer  138 , as well as a distal insertion member  140 , distal ring member  146  and sealing member  142 . However, this specific instrument version does not include a lens tube or an adapter interface member. In lieu of these components, the instrument head  104 A includes an eyepiece window  196  that is provided at the proximal end  116  within a cover portion  198  disposed within the rear housing portion  134 A. The eyepiece window  196  may or may not be configured to provide optical power (magnification) for enhanced viewing of the medical target. 
     With reference to  FIGS. 2( b ) ,  3  and  5 ( b ), the lower portion of each of the herein described instrument heads  104 ,  104 A retains an illumination assembly. According to this version, the light source of the illumination assembly is an LED  244 , which is disposed upon the upper surface of a printed circuit board  240 . The circuit board  240  is electrically coupled to a downwardly depending electrical contact  220 , the latter being retained within an insulator member  224  biased by a spring  254 , which is disposed within a lens retainer  248  provided above the circuit board  240 , along with a condensing lens  250 . The opposite end of the electrical contact  220  extends from an opening formed in the insulator member  224  and a handle stud base member  270 . The securing ring  280  is secured over the lower end of the handle stud base member  270 . The handle stud base member  270  includes an intermediate recessed portion  273  that is sized to retain the lower ends  131 ,  135  of the front and rear housing sections  130 ,  134 ,  134 A of the instrument head  104 , which is engaged by the securing ring  280 . According to at least one version, the securing ring  280  can include a locking element, such as, for example, a pin (not shown) that is insertable through a transverse opening  281  formed in the securing ring  280 . 
     The circuit board  240  is retained upon an upper shoulder of the handle stud base member  270  according to this embodiment. The condensing lens  250  is integrally molded as a domed section into the lens retainer  248  that is disposed above the LED  244  and circuit board  240 . According to this version, the lens retainer  248  is made from a moldable plastic. One end of the biasing spring  254  acts upon a surface of the lens retainer  248 , allowing the LED  244  and condensing lens  250  to be aligned and suitably positioned relative to the lower portion  141  of the innerformer  138  and more specifically a sleeve  144  that retains the polished end of a set of optical fibers (not shown). The optical fibers are advanced upwardly within the innerformer  138  and extend as a ringlet (not shown) that is provided in an annular spacing between the distal insertion portion  140  and the conical distal section  139  of the innerformer  138  in order to emit light toward the target of interest. 
     In operation, the contained LED  244  is engaged electrically via the contact  220 , as biased by the retained spring  254 . Upon energization of the LED  244  by the on/off switch  118 ,  FIG. 1( a )  provided on the handle portion  108 ,  FIG. 1( a ) , illumination from the LED  244  is directed through the condensing lens  250  with the collimated light being directed to the polished proximal end of the optical fibers (not shown) at a lower end of the innerformer  138 . As noted, the optical fibers (not shown) are directed through the innerformer  138  with the distal ends of the optical fibers being arranged in a ring-like configuration at the distal end opening of the distal insertion portion  140  and about the periphery of the hollow lens tube  152 . 
     Smart Device Adapter 
     As shown in  FIGS. 6-13 ( b ), a smart device adapter  300  in accordance with an exemplary embodiment is described. The smart device adapter  300  is releasably attachable to the proximal end  116 ,  FIG. 1( a ) , of a suitably configured physical assessment device, such as the previously described otoscope  100 ,  FIG. 1( a ) . The smart device adapter  300  according to this exemplary embodiment is defined by an housing or body  304  having a pair of housing sections, namely a front housing section  308  and a rear housing section  312 , which when assembled combine to create an interior that is suitably sized and shaped to retain a plurality of components. Each of the components of the smart device adapter  300  according to this embodiment are manufactured from a moldable plastic, although other suitable materials can be used. 
     The front housing section  308  of the smart device adapter  300  is defined by a lower portion  320 , which includes a semicircular slot  322  provided at one end. The semicircular slot  322  extends entirely through the thickness of the front housing section  308  with the exception of a device engagement section  328 , which is most clearly depicted in  FIG. 8( a ) , as well as  FIGS. 11( e ), 11( i ) and 11( j ) . 
     The device engagement portion  328  is defined by a pair of device engagement surfaces  330 ,  332 , each of which extend inwardly relative to the formed slot  322  and adjacent a front facing surface  309  of the front housing section  308 . These engagement surfaces  330 ,  332  are orthogonal to one another and have a defined thickness. 
     The front facing surface  309  of the front housing section  308  further includes a recess  335 ,  FIG. 6 , adjacent the defined semicircular slot  322  on one side of the slot  322  opposite one of the engagement surfaces  330 . The recess  335  is sized and configured to receive a slider member  350 , which is secured by a slider retainer  356 . According to this embodiment, the slider member  350  is defined by an upper plate  352  having an edge surface  354 , as well as a lower portion  353 . The slider retainer  356  is attached to the lower portion  353  of the slider member  350  using at least one fastener  358 , as well as engagement between a downwardly extending tab of the lower portion  353  of the slider member  350  and a corresponding slot formed in an upper surface of the slider retainer  356 . When positioned within the recess  335 , the edge surface  354  of the slider member  350  is positioned at the same plane as the two device engagement surfaces  330 ,  332 , thereby forming a third device engagement surface. As shown in  FIG. 8( b ) , a compression spring  346  is provided within a lateral cavity formed in the lower portion  353  of the slider member  350  that engages a spring pin provided on the front housing portion  308 , laterally biasing the slider member  350  and more specifically the edge surface  354  inwardly relative to the formed slot  322 . To facilitate movement, the underside of the upper plate  352  of the slider member  350  includes a set of rails  359  that are configured to slide within corresponding tracks  355  formed in the front housing portion  308 . 
     With reference to  FIGS. 6, 7, 11 ( b ) and  11 ( f ), the rear housing section  312  of the smart device adapter  300  includes respective interior and exterior surfaces  313 ,  314 . A slot  316  is formed at a lower end of the rear housing section  312 . The slot  316  is further defined by an interior ridge  324 . A peripheral border  326  formed on the interior surface  313  extends around the formed slot  316 , as well as the entire perimeter of the rear housing section  312 . As discussed herein, the portion of the peripheral border  326  about the slot  316  and the interior ridge  324  are sized and configured to support a detent cover  370 , as well as a device engagement member  360 . The peripheral border  326  includes a semicircular section at the lower end of the rear housing section  312  that corresponds to the semicircular slot  322  formed in the front housing section  308  of the herein described adapter  300 . A through opening  327  is also formed at the lower end of the rear housing section  308  as part of a protruding portion  340 . 
     According to this embodiment, the detent cover  370  is an elongate member having a front facing surface  371  and opposing rear facing surface  372  that is sized and configured to be fitted within the formed slot  316  of the rear housing portion  312 . A molded projecting portion  373  is provided on the front facing surface  371  of the detent cover  370  that is sized to accommodate a detent member  384 , as well as a detent spring  394 . The molded projecting portion  373  is circular in configuration according to this exemplary embodiment and includes a pair of diametrically spaced slots  375  that are sized to engage ears  389  formed on the detent member  384  to insure a predetermined placement within the projecting portion  373 . It will be readily apparent that the molded projecting portion  373  can assume other suitable configurations. The projecting portion  373  is further defined by a through opening extending entirely through the thickness of the detent cover  370 , the opening enabling access to a projecting detent  391 . 
     Adjacent the molded projecting portion  373  on the front facing surface  371  of the detent cover  370  is a formed recess  376  that is sized and configured to receive a strip of insulating material  395 . According to this embodiment, the strip of insulating material  395  is made from an open-celled foam material such as poron, although other similar materials can be utilized. 
     The device engagement member  360  is attachable to the rear housing section  312  of the smart device adapter  300  and more specifically is attachable to the formed slot  316 . According to this embodiment, the device engagement member  360  is elongate and defined by opposing planar front and rear facing sides  361 ,  362 , respectively. The rear facing side or surface  362  of the device engagement member  360  receives an adhesive strip  363 , which can be fitted thereto. According to one version and with reference to  FIGS. 6, 7 and 12 ( a )- 12 ( h ), the rear facing surface  362  of the device engagement member  360  is defined by a recess  366  sized to accommodate the adhesive strip  363  and position it in a predetermined location and orientation. According to another version, the adhesive strip can be removed and relocated anywhere on the rear facing side  362 . The front facing side  361  of the device engagement member  360  includes a groove  367  which is formed transversely relative to the major dimension of the member  360  and adjacent one end. 
     An exemplary assembly flow is provided in  FIGS. 10( a )-10( e ) . First and with reference to  FIG. 10( a ) , the slider member  350  is attached to the front housing section  308  and fitted within the formed recess  335  with the lower portion  353  of the slider member  350  extending through an access slot provided in the front facing surface  309 . The compression spring  346  is engaged within the lateral slot formed in the lower portion  353  of the slider member  350  wherein one end of the compression spring  346  is engaged with a spring pin (shown in  FIG. 10( a ) ). As shown in  FIG. 10( b ) , the slider retainer  384  is then attached to the slider member  350  through the access slot by engaging the tab of the lower portion  353  with the corresponding slot formed in the upper surface of the slider retainer  356  and inserting the fastener  358  to secure the slider retainer  356  and the slider member  350  within the recess  335  of the front housing portion  308 . 
     As shown in  FIG. 10( c ) , the strip of insulating material  395  is added to the recess  376  formed in the rear housing section  312  and the detent member  384  and detent spring  394  is placed within the projecting enclosure  373  of the detent cover  370 , aligning the ears  389  of the detent member  384  with the corresponding spaced slots  375  formed on the projecting enclosure  373 . Once the foregoing components are in place, the detent cover  370  is placed onto the interior side of the rear housing section  312  and more specifically, the slot  316  with a bordering edge of the detent cover  370  being placed on the peripheral border  326 . 
     As shown in  FIG. 10( d ) , the front housing section  308  having the assembled slider member  350  and slider retainer  356  is then aligned with and attached to the rear housing section  312  having the assembled detent cover  370 , detent member  384  and detent spring  394 , as well as the strip of insulating material  395 . 
     Finally and as shown in  FIG. 10( e ) , the rear housing section  312  and the front housing section  308  are secured using a series of threaded fasteners  317  through a series of mounting holes  315  provided in each of the rear housing portion  312  and front housing portion  308  of the smart device adapter  300 . When assembled, the detent cover  370  is sandwiched within the interior of the smart device adapter  300  along with the detent member  384 , the detent spring  394  and the strip of insulating material  395 , and with the slider member  350  also attached as shown. 
     The device engagement member  360  can then be slidingly attached to the slot  316 . With reference to  FIGS. 9( a ), 9( b ), 11( a ), 11( b ) and 11( k ) , the detent member  384  is retained in the interior of the adapter  300  within the detent cover  370 . The detent member  384  according to this embodiment includes a projecting detent  391  that is sized and shaped to engage the transverse groove  367  formed on the front surface  361  of the device engagement member  360  when the device engagement member  360  is attached by sliding the device engagement member  360  within the open end of the formed slot  316 . 
     As shown in  FIGS. 9( a ), 9( b ) and 11( a )  and as the device engagement member  360  is engaged within the slot  316  of the rear housing section  312 , the bias of the detent spring  394  enables the detent member  384  to be moved slightly forward relative to the transverse groove  367  formed in the device engagement member  360  to provide greater retention when the device engagement member  360  is attached to the adapter  300 . The strip or pad of insulating material  395  eliminates rattle and provides a defined drag when a user slides the device engagement member  360  in the defined slot  316 . The device engagement member  360  is slid an appropriate distance within the slot  316  until the front surface of the device engagement member  360  engages the spring loaded detent member  384 . Preferably, there is a slight mismatch created between the projecting detent  391  and the transverse groove  367  formed in the device engagement member  360  that biases the device engagement member  360  forward. Additional views of the front and rear interfacing portions of the smart device adapter  300  illustrating each of the foregoing features are depicted in  FIGS. 11( a )-11( l ) . 
     In operation, the device engagement member  360  can first be attached to a smart device using a fixture (not shown) to a facing surface of a smart device. The device engagement member  360  is preferably located on the smart device (e.g., smart phone) in a position that enables the optical axis of the smart device to be aligned with the optical axis of the physical assessment device when the smart device is attached. The through opening  327  of the rear housing section  312  is aligned with the optical axis of the smart device when the device engagement member  360  is attached to the smart device. When attached, the protruding portion  340  formed on the rear housing portion  312  of the adapter  300  minimizes the intrusion of ambient (room) light into the system. 
     With reference to  FIG. 13( a ) , the smart device adapter  300  is attachable to the proximal end  116  of the physical assessment device  100  by aligning the device engagement portion  328  of the adapter  300  with the recess  184  of the adapter interface member  180 . The three engagement surfaces  330 ,  332  and  354  have a thickness that enables a fit within the recess  184  of the adapter interface member  180 . Moreover, the configuration of the three (3) device engagement surfaces  330 ,  332  and  354  of the smart device adapter  300 , including their length and relative spacing enables releasable attachment of the smart device adapter  300  relative to the recess  184  of the adapter interface member  180 , and more specifically the machined flats  186 . The slot  322  of the front housing section  308  of the adapter  300  is sufficiently wide so as to accommodate the proximal section  188  of the adapter interface member  180 , including the brow rest  194 . 
     As noted, the engagement surface  354  is biased due to the spring loaded slider member providing consistent peripheral contact of the engagement surfaces  330 ,  332  and  354  with the machined flats  186 . In addition, the axial openings of the adapter interface member and more specifically the spring loaded balls  187  of the adapter interface member  180  against the intermediate plate  190 , further bias the attached smart device adapter  300  in the direction of the optical axis of the physical assessment device  100  and provide a stable mounted platform for purposes of conducting an examination. 
     For purposes of positioning, the smart device adapter  300  (and attached smart device (not shown) can be placed in one of four (4) different positions, each position clocked about 90 degrees about the optical axis of the physical assessment device  100 . According to this embodiment, the smart device adapter  300  is removed from the physical assessment device  100  and rotated before reengaging the slots of the adapter  300  with the machined flats  186  of the adapter interface member  180 . This adjustment can be made either with or without a smart phone being attached to the smart device adapter  300 . It will be understood, for example, that the number of machined flats can be suitably varied in order to provide a suitable number of mounting positions. 
     According to another embodiment, the herein described adapter can be fitted to a physical assessment device, such as an otoscope or ophthalmoscope, without prior optical alignment using a calibration device. Instead of attaching the device engagement member  360  adhesively or otherwise to the smart device following calibration, the device engagement member  360  is initially attached to the smart device adapter  300  by sliding the device engagement member  360  into the slot  316  provided on the rear housing portion of the adapter  300  until there is an audible or other indication that the device engagement member  360  has been placed at a predetermined position. In at least one version, an audible click or other indication, such as a detent is provided to the user. The adhesive layer  363  of the device engagement member  360  is then removed to enable the device engagement member  360  to be attached to a facing surface of the smart device, wherein visual alignment by the user aligns the through opening  327  in the adapter  300  with the optical axis of the attached smart device. The two components can then be assembled by pressing the adhesive surface  363  of the device engagement member  360  against the front facing side of the smart device. To remove the smart device from the adapter  300 , the smart device can be pulled from the device engagement member  360 . This technique permits a varied number of differently sized smart devices to be releasable fitted to a common smart device adapter  300 . 
     As shown by the ray trace depicted in  FIG. 13( b )  for the physical assessment device  100  including instrument head  104  and attached smart device adapter  300 , the optical assembly of the herein described otoscope  100  creates a virtual distal entrance pupil  125  within the attached speculum tip element  120 ,  FIG. 2( a ) . The position of the formed entrance pupil according to this embodiment is well distal of the optical window and objective lens. The entrance pupil is positioned such that the attached speculum tip element  120  is not “seen”; that is, the rays of light reflected from the medical target pass sufficiently within the tip opening of the speculum tip element  120 ,  FIG. 2( a ) , while still enabling a large field of view, permitting the entire tympanic membrane to be viewed all at once. As shown, the light reflected from the medical target is directed along a defined optical axis to the optics of an attached smart device, not shown. The advantageous effect of the entrance pupil is further illustrated in  FIGS. 54( a )  and  55 . 
     With reference to  FIGS. 14-16 , a variation of the smart device adapter  400  is described for use on another physical assessment device  450 . Similar parts are labeled with the same reference numerals for the sake of clarity. According to this embodiment, the physical assessment device  450  is a Pan Optic™ Ophthalmoscope sold commercially by Welch Allyn, Inc. of Skaneateles Falls, N.Y. The ophthalmoscope  450  is defined by an instrument head  454  that can be releasably attached to a handle portion (not shown). The instrument head  454  includes a distal (patient) end  456  and an opposing proximal (caregiver) end  459 . An optical system (not shown) within the instrument head  454  is configured to enable examinations of the eye of a patient, along with a contained illumination system (not shown) that includes at least one light source to illuminate the eye being examined. 
     According to this embodiment, aspects of the smart device adapter  400  are structurally and functionally similar to the version previously described in  FIGS. 6-13 ( a ), including a pair of housing portions  308 ,  312  that retain a detent cover  370  as well as a detent member  384 , the latter being biased by a contained detent spring  394 . The rear housing portion  312  includes a slot  316  that is configured to receive the detent cover  370 , as well as a device engagement member  360  that is slidably engaged with the slot  316  formed on the adapter  400  and including a transverse groove  367  that engages the detent member  384 . The housing portions  308 ,  312  are secured to one another using a set of fasteners  317 , The adapter  400  further includes a through opening  327  that is aligned with the optical axis of the physical assessment device  450  when the adapter  400  (and smart device  480 ) are attached, as shown in  FIG. 16 . 
     The smart device adapter  400  according to this embodiment further includes a flexible arm  420  having a distal end  424  that includes a ring-shaped portion  428 . The ring-shaped portion  428  is sized to enable it to be disposed over the downwardly extending portion  458  of the instrument head  454 . The proximal end  429  of the flexible arm  420  can be releasably attached to the front housing section  308  of the smart device adapter  400 . According to this version, the front housing section  308  includes an opening  433  that is sized to receive the proximal end  429  of the flexible arm  420 . 
     With reference to  FIGS. 17-20 , a smart device adapter made in accordance with another exemplary embodiment is herein described. First and referring to  FIG. 17 , a known physical assessment device  500  and the otoscope  100 ,  FIG. 1( a ) , are shown in side by side relation. As previously discussed, the otoscope  100  includes an adapter interface member  180  at its proximal end  116  that enables a smart device adapter  300 ,  FIG. 6 , to be releasably attached. The known assessment device  500 , which is a Macroview™ otoscope, commercially sold by Welch Allyn, Inc. of Skaneateles Falls, N.Y., can also be configured with an adapter to enable a smart device to be attached. The known device is defined by an instrument head  554  that includes a distal (patient) end  556  and an opposing (caregiver) end  559 , wherein the instrument head  554  is attached to the upper end of a handle portion  558 . A speculum tip element  560  is attached to the distal end  556  of the instrument head  554 . An optical and an illumination assembly (not shown) are contained within the instrument  550 , including an eyepiece  563  provided at the proximal end  558  and a focusing wheel  562  intermediately provided on the exterior of the instrument head  554  that enables relative movement of at least one contained optical element (not shown). 
     With reference to  FIGS. 18-20 , a smart device adapter  500  according to this embodiment includes a support or base plate  504  having an upper portion  508  and an opposing lower portion  512 . The support plate  508  can be made from a durable molded plastic, although other structural materials can be suitably utilized. The upper portion  508  includes a through opening  516 , as well as a hollow cylindrically shaped projection  520  that is aligned with the through opening  516 . The hollow projection  520  extends distally from the upper portion  508  and is defined by a cavity that is sized and configured to be fitted over the proximal end  558  and more specifically the eyepiece  563  of the known physical assessment device  550 . A flexible engagement portion  522  formed at the lower portion  512  of the base plate  504  is defined by a C-shaped engagement end  524 . This engagement end  524  is sized and configured to releasably engage the cylindrical handle portion  558  of the known physical assessment device  500 . Though the known physical assessment device  550  is an otoscope, it will be readily apparent to those in the field that other handheld medical diagnostic devices can be similarly configured for attachment. 
     With further reference to  FIGS. 18-20  and in terms of attachment, the projecting cylindrical portion  520  is first fitted onto the proximal end  558  of the physical assessment device  550 . This fit still enables the caregiver to access the focusing mechanism  562  of the physical assessment device  550 . The smart device adapter  500  is then rotated until the open end of the C-shaped engagement feature  524  is aligned with the handle portion  558 , permitting the C-shaped engagement feature  524  to be clamped onto the handle  558 . The C-shaped engagement portion  556  is angled relative to the base plate  504  to account for the angled configuration of the instrument head  554  of the otoscope  550 . 
     A smart device such as a smart phone (not shown) can be attached to the proximal side of the support plate  504  in a manner similar to those previously described. Advantageously, the herein described adapter  500  can be attached to a physical assessment device in a matter of seconds, thereby converting the physical assessment device from an optical to a digital physical assessment device without requiring any modification to the device. Once attached, the smart device permits users to use the physical assessment device  550  to take pictures and video and then seamlessly transfer the images or video to a digital medical record or other digital storage medium used in an office or hospital. 
     Variations—Otoscope 
     An otoscope  1100  made in accordance with another exemplary embodiment is depicted in  FIGS. 21 and 23 . According to this embodiment, the instrument head  1104  of the otoscope  1100  is defined by a distal end  1112 , an opposing proximal end  1116  and a downwardly extending portion  1120  attached to the handle  1108 , the latter being shown only in  FIG. 21 . A disposable hollow speculum tip element  1124  is releasably attached to the distal end  1112  of the instrument head  1104  and more specifically to a tip retaining member  1170 , while an optical window  1128  is provided at the proximal end  1116 . In use, the speculum tip  1124  is shaped and configured to be inserted a predetermined distance into the ear of the patient and the optical window  1128  enables viewing of a medical target of interest (e.g., the tympanic membrane) through the open distal opening  1125  of the speculum tip  1124 . 
     With reference to  FIGS. 22 and 24 ( a ), an alternative instrument head  1204  of an otoscope  1200  is similarly defined by a distal end  1212 , an opposing proximal end  1216  and a downwardly extending portion  1220 . A disposable speculum tip element  1124  is releasably attached to the distal end  1212  of the instrument head  1204  and more specifically a tip retaining member  1170 . As shown in  FIG. 24( b ) , a rear mounting member  1224  (also referred to throughout as an adapter interface member) extending from the proximal end  1216  is configured to receive a smart device  1230 , such as a smart phone, using an interface member  1240  that aligns the electronic imager of the smart device  1230  with an optical axis of the instrument  1200  to enable digital imaging of the target of interest (e.g. the tympanic membrane) via the display  1234  of the attached smart device  1230 . 
     Assembly of the instrument head  1104  is shown in  FIGS. 25( a )-25( d ) . The instrument head  1104  according to this embodiment includes a pair of housing sections  1134 ,  1138  (one housing section  1134  being shown as exploded in  FIG. 25( a ) ) that are mated to one another about an innerformer  1140 , the latter component creating an interior chamber for the instrument head  1104 . An interface stud  1150  extends downwardly from the innerformer  1140  into the downwardly extending portion  1120  of the instrument head  1104  to enable connection to the instrument handle  1108 ,  FIG. 21 . A conically-shaped distal insertion portion  1160  is provided at the distal end  1112  of the instrument head  1104  onto which the speculum tip  1124  is placed in overlaying relation and releasably secured to the tip retaining member  1170 . A proximal housing member  1180  is secured to the rear end of the innerformer  1140 . The proximal housing member  1180  includes a mounting flange  1184  having a pair of spaced slots  1186  that permits the transverse attachment of the optical window  1128 . Between the mounted proximal housing member  1180  and the rear of the innerformer  1140  is a groove  1187  that permits the inclusion of a sealing member (not shown). A retaining ring  1190  threadingly attached to the interface stud  1150  secures the housing sections  1134 ,  1138  together and a cover  1142  attached to the top of the instrument head  1104  covers the mating edges of the housing sections  1134 ,  1138 . 
     With reference to  FIGS. 26( a )-26( b ) , the assembly of the instrument head  1204  similarly incorporates the housing portions  1134 ,  1138  that are mated about the innerformer  1150 , the latter component forming an interior compartment of the instrument head  1204 . Similarly, this assembly incorporates a cover  1142 , the distal insertion portion  160  and the tip retaining member  1170  as well as an interface stud  1150  and threadingly retained retaining ring  1190  extending downwardly into the narrowed neck portion  1220 . In lieu of the proximal housing member that retains an optical window, the rear mounting (adapter interface) member  1224  is disposed at the proximal end  1218  of the instrument head  1204 . According to this embodiment, and similar to the design previously discussed (see  180  at  FIG. 1( a ) ), the rear mounting member  1224  has a defined mounting flange  1226  and an annular slot  1228  that is configured to receive the interface member (smart device adapter)  1240  and attached smart device  1230 , as shown in the assembled form previously shown in  FIG. 24( b ) . 
     Sectioned views of the assembled instrument heads  1104 ,  1204  are shown in  FIGS. 27 and 28 . respectively. Referring to  FIG. 27 , the instrument head  1104  of the otoscope  1100 ,  FIG. 21 , enables an image of the medical target (e.g., the tympanic membrane) to be seen through the proximal end  1116  of the instrument head  1104  by viewing through the optical window  1128  as supported by the proximal housing member  1180 . This enables viewing of the medical target (e.g. tympanic membrane) through the interior compartment created by the innerformer  1140  and the distal openings  1127 ,  1161  that are formed in the distal insertion portion  1160  and speculum tip  1124 , respectively. 
     With reference to  FIG. 28 , an optical assembly is disposed in the interior of the instrument head  1204  of the otoscope  1200  according to this exemplary embodiment. Portions of the optical assembly are retained within a tubular member (also referred to throughout as a lens tube) disposed within the interior compartment created by the innerformer  1140  including a plurality of optical elements, each aligned and disposed along a defined optical or viewing axis of the device  1200  extending between the distal and proximal ends  1212 ,  1216  of the instrument head  1204 . The specifics of the optical assembly are more specifically described in a later portion of this description. As referred to herein, an “optical element” refers to lenses and prisms as well as field stops, aperture stops, polarizers, and any component used to directing or transmitting light along the defined optical or viewing axis. As in the prior described versions of the physical assessment device  100 ,  FIGS. 1( a ), 13( b ) , the optical assembly according to this exemplary embodiment produces an entrance pupil distal relative to the distal most optical element of the optical assembly, creating a field of view that permits the entire tympanic membrane (about 7 mm for an average adult) to be seen all at one time. 
     A sealing member  1250  is further provided at the rear of the innerformer  1140  as engaged within a formed annular groove  1187 . The sealing member  1250  provides an adequate seal to the formed interior compartment of the instrument head  1204  in order to permit insufflation capability (insufflation port not shown in this view) and also preventing fogging of the retained optical elements. 
     Each of the otoscopic instrument heads  1104 ,  1204  depicted in  FIGS. 27 and 28  commonly include an illumination assembly that is disposed within the downwardly extending portion  1120 ,  1220  and more specifically the interface stud  1150 . The illumination assembly according to this embodiment is more clearly shown in  FIG. 33  and includes an LED  1270  as a light source. More specifically, the LED  1270  is disposed upon the upper surface  1272  of a printed circuit board  1274  that is electrically coupled to a downwardly depending electrical contact  1278  biased by a spring  279  disposed within an internal sleeve  1280 , the distal end of the electrical contact  1278  extending from an opening of a narrowed portion of the internal sleeve  1280  and proximate an opening  1285  formed in the bottom of the instrument head  1104 ,  1204 . The LED  1270  is disposed in relation to a condensing lens  1290  and the polished proximal end of a fiber optic bundle  1287 , the latter of which is advanced upwardly about the innerformer  1140  and extends as a ringlet of optical fibers (not shown) between the distal end of the distal insertion portion  1160  and the innerformer  1140  in order to emit light toward the target of interest. 
     In each of the above noted devices  1100 ,  1200  and as described, the pair of housing sections  1134 ,  1138  can be secured to one another at corresponding mating edges by means of ultrasonic welding with a cover  1142  being introduced at the top of the instrument head  1104 ,  1204 . 
     With reference to  FIGS. 29 and 30  and according to yet another exemplary embodiment, instrument heads  1304 ,  FIGS. 29, and 1310 ,  FIG. 30  are shown. Each of these instrument heads  1304 ,  1310  are similar to instrument heads  1104 ,  1204 . Instrument heads  1304  and  1310  include a pair of mating housing shell sections  1324 ,  1328  that are attached to one another using an intermediate member, herein referred to as a strap  1340 . For purposes of clarity, like structural components are herein labeled with the same reference numerals. The strap  1340  according to this specific embodiment is a singular member made from a flexible, but structural material and having an upper portion  1344  and a lower portion  1348 . 
     As shown more specifically in  FIG. 31 , the upper portion  1344  of the strap  1340  is defined by a rounded interior surface  1346  configured and sized to wrap around the exterior of the respective first and second housing shell sections  1324 ,  1328  after the mating edges of the housing sections  1324 ,  1328  have been placed in intimate contact with one another. According to this embodiment, the housing shell sections  1324 ,  1328  define respective halves of the instrument head  1304 ,  1310 . Each of the housing sections  1324 ,  1328  includes a recess  1330  formed in the exterior surface into which the strap  1340  is received such that the exterior surface of the strap  1340  is substantially coplanar with the exterior surface of the mated housing sections  1324 ,  1328  when attached. 
     During assembly/manufacture, the inner edges of the pair of housing sections  1324 ,  1328  are placed in intimate contact and the strap  1340  is snap-fitted into place onto the instrument head  1304  via the recess  1330 . As shown in  FIGS. 31 and 32 , the lower extending portions  1348  of the intermediate strap  1340  each include an annular flange  1352  formed on an inner surface, as well as an annular shoulder  1356  formed at the end of each lower extending section  1348 . Referring to  FIG. 32 , the annular flange  1352  of each lower extending section  1348  is retained within an annular groove  1153  formed in the interface stud  1150  and secured by means of the retaining ring  1190  by threading engagement with the bottom of the interface stud  1150  of the instrument head  1304 , the upper end of the retaining ring  1190  engaging the shoulder  1356 . 
     With reference to  FIG. 33-36 , an illumination assembly is retained within the downwardly extending portion  1120  of the instrument head  1104 . According to the depicted embodiment, the illumination assembly includes the LED  1270  attached in a known manner to a top or upper surface  1272  of a printed circuit board  1274 . Disposed above the LED  1270  and printed circuit board  1274  is an integrated component  1420  that serves to center and align the LED  1270  and also collimates the light that is emitted from the LED  1270 . The outer edges  1275  of the printed circuit board  1274  are retained upon an interior shoulder  1156  of the interface stud  1150 . As shown in the sectioned view of  FIG. 34 , the integrated component  1420  is defined by a cylindrically shaped body  1422  having an upper end  1426 , a lower end  1430 , and a set of external threads  1434  extending along the length of the integrated component  1420 . An interior flange  1438  is disposed at an intermediate distance between the upper and lower ends  1426 ,  1430  of the integrated component  1420 , the flange  1438  having respective and opposing top and bottom surfaces  1442 ,  1446 . 
     A domed portion  1450 , which is provided at the center of the top surface  1442  of the internal flange  1438 , is axially aligned with the LED  1270  and acts as a condensing lens. An annular ring  1458  extending downwardly from the bottom surface  1446  of the interior flange  1438  is configured and sized to surround the lens envelope of the LED  1270  and functions to center the domed portion  1450  with the LED  1270 , thus minimizing decentration between the LED  1270  and the domed portion  1450  and any associated losses in light transmission. The set of external threads  1434  are configured to mate with corresponding internal threads  1460  that are provided in the interface stud  1150  of the instrument head  1104 . This mating allows the integrated component  1420  itself to fasten the printed circuit board  1274  into the interface stud  1150  and further ensure a secure electrical contact between the printed circuit board  1274  and the interface stud  1150 . This securement further prevents ingress of dirt and debris. 
     According to this particular embodiment, a series of notches  1468  are provided in spaced relation along the upper end  1426  of the integrated component  1420 , as shown in  FIG. 35 . The notches  1468  are shaped and configured to accept protrusions provided in a complementary driving or torqueing tool (not shown) for purposes of assembly. The printed circuit board  1274  according to this embodiment further includes an outer ground ring that makes intimate electrical contact with a metal stud. The threaded connection between the integrated component  1420  and the interface stud  1150  of the instrument head insures a secure high pressure mating at this junction. As noted, the domed portion  1450  collimates illumination from the LED  1270 . Advantageously, the design of the integrated component  1420  serves to save manufacturing costs and labor and also reduces tolerance build ups, as well as preventing or minimizing ingress of dirt and contaminants. 
     An embodiment depicting the interconnection between an instrument head  1104  and instrument handle  1108  for the physical assessment device  1100  of  FIG. 21  is illustrated in the sectioned view of  FIG. 37 . As shown, the instrument handle  1108  is a substantially cylindrical member having an upper or top end and an opposing lower end, as well as at least one interior compartment that is sized and configured to retain at least one battery for powering the contained light source in the instrument head  1104 . It should be noted that similar connections are provided for the instrument heads previously described in this application. 
     Each of the instrument heads  1104 ,  1204  such as those shown in  FIGS. 27 and 28  and having an LED  1270  as a contained light source can be interchangeably attached to the instrument handle  1108  by means of a bayonet connection between the top end of the instrument handle  1108  and the narrowed neck portion of the instrument head  1104 . Known physical assessment devices, such as those commercially sold by Welch Allyn, Inc provide a bayonet connection between the instrument head and the instrument handle. More specifically, a set of spaced lugs are provided on the top of the instrument handle that engage a corresponding slot formed in the lower end of the instrument head when the instrument head is twisted in a predetermined direction. 
     As noted, each of the previously described instrument heads, including instrument heads  1104 ,  1204  or  104 ,  FIG. 13( b ) ,  104 A,  FIG. 5( a ) , include an LED as a light source for the contained illumination assembly. 
     There is a need with the evolution of LEDs as light sources in physical assessment devices to prevent instrument handles, especially those wired to wall mounted systems that will not power instrument heads equipped with halogen lamps. Halogen lamps draw large currents and the associated voltage drop through wall unit power cords. This voltage drop makes compliance with safety standards difficult and forces the further inclusion of expensive electronics. LED systems, on the other hand, draw relatively small currents and do not have this drawback. As instrument heads evolve and utilize LED as illumination sources, it is anticipated these instrument heads can be used with existing instrument handles. However and as wall mounted systems also evolve, it is a desire to prevent the use of existing instrument heads having halogen lamp light sources. 
     With reference to  FIGS. 37-43 , an embodiment is herein described to enable an instrument handle to be incompatible with certain instrument heads (i.e. those having halogen lamps). With reference to  FIG. 38 , an instrument handle  1602  includes a top portion  1604 . A pair of equally spaced male lugs  1612  are provided on the exterior of the top portion  1604  of the instrument handle  1602 . Each lug  1612  according to this embodiment is defined by a width dimension denoted by arrows  1616  that enables the lug  1612  to be fitted within a defined bayonet slot of a mated instrument head. 
     An instrument head  1620  is shown in  FIGS. 39 and 40 . In this instance, the physical assessment device is an ophthalmoscope, but the principle is common to other physical assessment devices, such as the previously described otoscopes. The mating connection is provided at the bottom of the instrument head  1620  and includes an interface stud  1624  whose bottom end  1628  is defined with a contoured slot  1632  to provide a secure locking engagement when the instrument head  1620  is rotated relative to the instrument handle  1602  by means of a bayonet connection. 
     The assembled interface is shown more clearly in  FIGS. 41 and 42  with each of the spaced lugs  1612  of the instrument handle  1602  engaged within the contoured mating slot  1632  of the instrument head  1620 . In this mounted position, the electrical contacts  1640 ,  1646  of the instrument head  1620  and the instrument handle  1602  are positioned into contact with one another. For purposes of this embodiment and referring to  FIG. 42 , the width dimension of the contoured mating slot  1632  is increased enabling interchangeability between various instrument heads and handles. With reference to  FIG. 43 , the width dimension of the mating lugs  1612  of the instrument handle  1602  can be increased such that the lugs  1612  will not fit within the mating slot (not shown) of an already existing ophthalmic instrument head having a halogen light source. 
     Referring to  FIG. 44 , an exemplary instrument handle  1706  is shown having a upper end  1707  including a top portion  1709  and an opposing bottom end  1711 . A partially sectioned view of the upper end  1707  of the instrument handle  1706  is further depicted in  FIG. 45 . More specifically, the upper end  1707  includes a rheostat assembly  1712  that selectively adjusts the level of illumination of the retained light source, such as the at least one LED  1270 ,  FIG. 33 , when the instrument head (not shown) is attached to the instrument handle  1706 . This connection is made using bayonet engagement features provided on each of the mated components such as those previously discussed. When connected, the LED  1270 ,  FIG. 33 , is powered through coupling between the retained battery  1714  (partially shown in  FIG. 45 ), the rheostat assembly  1712 , the electrical contact  1717  biased by spring  1721  and the electrical contact  1640 ,  FIG. 40 , in order to electrically couple the LED  1270 ,  FIG. 33 , with the battery  1714 . 
     Referring to  FIGS. 45-48  and according to one embodiment, the rheostat assembly  1704  includes a twistable grip section  1718  that is provided on the exterior of the instrument handle  1706 . The twistable grip section  1718  is disposed over a cylindrically shaped detent ring member  1722  having a series of holes  1726  arranged along its periphery proximate a lower end  729  of the detent ring member  1722 , as shown more clearly in  FIG. 47 . A pin member  1732  extends within an annular recess  1734  formed in the detent ring member  1722  and is biasedly retained within a recess  1736  formed in an internal sleeve  1750 . A ball  1740  is also biasedly retained in an opening formed in the internal sleeve  1750  which is diametrically opposite that of the pin member  1732 . The ball  1740  is configured to rotate with the twistable grip section  1718  and is caused to extend into one of the holes  1726  in the detent ring member  1732 , the latter being stationary to create an audible and tactile sensation for the user. Each of the ball  1740  and the pin member  1732  are biased by springs  1744 ,  1748  which are disposed within the diametrically opposed openings in the internal sleeve  1750  extending in a direction that is transverse to a primary axis of the instrument handle  1706 . The detent ring member  1732  includes the set of interior threads  1725  that engage a corresponding set of external threads  1757  provided on a rheostat housing  1758 . 
     In operation, the twistable grip section  1718  rotates around the stationary detent ring member  1722 . The pin member  1732  keys into the twistable grip section  1718  and rotates with the grip section  1718  when twisted by a user. The spring-loaded ball  1740  also rotates with the twistable grip section  1718  and depending on the rotational position of the grip section  1718  detents into one of the series of holes  1726  provided in the stationary detent ring member  1722 . Attributes of the spring  1748  biasing the ball  1740  can be suitably varied as needed in order to provide a desired detent release force. The foregoing provides audible and tactile feedback about the location of the rheostat. This feature allows a user of the instrument to create a preferred setting which can repeated to obtain a consistent amount of light with each use. The detent positions and size and configuration of the detent stops can be altered in order to provide a different sound or release strength at different or selected positions, such as the zero position or other rheostat position. 
     With reference to  FIGS. 48 and 49 , the instrument handle  1706  can be equipped with a USB charging or power boosting port  1760 . According to this embodiment, the USB port  1760  is provided on the exterior of the instrument handle  1706  and proximate the bottom or lower end  1711 . It will be understood, however, that the location of this port  1760  can be suitably varied relative to the instrument handle  1706 . With reference to the sectioned view of  FIG. 49  and according to this embodiment, the charging port  1760  extends to a USB connector  1768  mounted to the top surface of a printed circuit board  1772  that is disposed within the interior of the instrument handle  1706  in which contacts extend to the contained battery  1714  (partially shown in this view). According to this embodiment, a set of electrical charging contacts axially extend from the lower end  1709  of the instrument handle  1706  enabling the instrument to be used in conjunction with a charging base or cradle  1800 ,  FIG. 52 , that enables the at least one contained battery  1714  to be recharged. 
     According to this embodiment and with reference to  FIGS. 49 and 50 , a positive contact  1777  extending from the lower end  1709  of the instrument handle  1706  is soldered to the printed circuit board  1772  via a connection  1779  and a conductive spring clip  1782  is provided to serve as a negative contact connecting an outer ring  1713  at the bottom end  1711  of the instrument handle  1706  with the printed circuit board  1772 , the latter being electrically coupled to the lower contact end of the battery  1714 . As such, the herein described instrument handle  1706  can be configured with dual charging modes. 
     The norm in the medical industry is to charge the instrument handle (power source) through either a desk charger or more recently using USB. With reference to  FIG. 50 , a circuit is depicted that allows one or more instrument handles to be charged through a desk charger, such as base  1800 , or the USB charging port  1760 . This charging circuit uses a charging IC and accepts power from either a USB input or via positive and negative contact pins. 
       FIG. 51  illustrates a sectioned view of the alternative charging mode with the electrical contacts  1777  and  1782  being coupled to respective charging pins  1809  that are provided within a charging well  1814  of the charging base  1800 , which is only partially shown in this view. 
       FIG. 52  provides a perspective view of a charging base  1800  made in accordance with an embodiment and including a pair of charging wells  1814  extending from a top surface  1811 . Each of the charging wells  1814  are sized to receive an instrument handle  1822 ,  1832  of a physical assessment device  1820 ,  1830  and provide a stable base, the charging wells  1814  having a defined height that creates a stable base for the retained physical assessment devices  1820 ,  1830 . With continued reference to  FIG. 52 , a pair of physical assessment devices  1820 ,  1830  and more specifically, an ophthalmoscope and an otoscope are commonly retained in separate charging wells  1814  of the charging base  1800  in which each of the retained devices  1820 ,  1830  includes an attached smart device  1828 ,  1838 , such as a smart phone. The two physical assessment devices  1820 ,  1830  are mounted at the same time, as shown, with the respective instrument handles  1824 ,  1834  being inserted into the charging wells  1814  such that the retained smart devices  1828 ,  1838  are opposed to one another. In this mounted position, there is with no interference between the mounted devices or between either retained physical assessment device  1820 ,  1830  and the charging base  1800 . 
     According to one version and as shown in  FIG. 53 , a thermistor, thermocouple  1790  or other temperature determining apparatus can extend from the printed circuit board  1772  within the instrument handle  1706  by connection  1792  and be disposed in relation with the contained battery  1714 . The output of the thermistor  1790  provides direct battery temperature measurement during charging and discharging of the battery  1714  which can further be coupled to an indicator (not shown) on the charging base  1800 ,  FIG. 52 , or the instrument handle  1706 . As such, potential overheating of a contained battery, such as an alkaline battery, can be monitored. 
     Due to the fact that both halogen lamp based and LED-based instrument heads may be used interchangeably, instrument handles should be designed so as to prevent overheating of a contained alkaline battery, especially if a halogen-based instrument head is attached. 
     An example of an electrical circuit intended to solve this problem is depicted in  FIG. 53 , preventing overheating of a contained battery. The electrical circuit employs a voltage boost design with input current limit (such as Texas Instruments TPS 61251). With this circuit&#39;s design, a current limit can be set on the voltage boost IC so that if a halogen based lamp is connected to the instrument handle having an alkaline battery, the current will be limited and not exceed the battery&#39;s limit that would cause overheating. 
     In addition, this voltage boost IC will enable improved performance of an instrument head that is equipped with an LED as a light source and subsequent use of LED replacement lamps. 
     As discussed, the interior of at least one of the herein described instrument heads  104 ,  FIG. 2( b ) ,  FIGS. 13( b )  and  1204 ,  FIG. 28 , can retain an optical system or assembly that includes a plurality of components aligned along an optical or viewing axis extending through the distal end opening  124 ,  1125  of the hollow speculum tip element  120 ,  1124 , which is releasably attached to the instrument head  104 ,  1204  and continuing through the interior of the instrument head  104 ,  1204 , passing through the proximal end  1014 ,  1216  thereof. 
     Reference is herein made to  FIG. 54( a ) , which depicts a ray trace of the optical system or assembly  1900  of the physical assessment device  100 ,  FIGS. 2( b ) and 13( b )  and  FIG. 54( b ) , providing a comparison between three (3) additional optical assemblies  1910 ,  1940  and  1950  for an exemplary instrument head, including that of instrument head  1204 . The bottommost optical assembly  1910  depicted is representative of a known optical assembly which is fully described in U.S. Pat. No. 7,399,275, and incorporated herein by reference in its entirety. 
     First and with reference to  FIG. 54( b ) , the known optical assembly  1910  includes a distal objective lens doublet  1914  that would be disposed proximate the distal opening of the distal insertion portion  1160 ,  FIG. 28 , of the instrument head  1204  having an attached speculum tip element  1124 . A pair of aligned relay lenses  1919 ,  1922  are disposed proximally to the objective lens doublet  1914 , as well as an aperture plate  1920  disposed between the pair of relay lenses  1919 ,  1922 . A set of eyepiece lenses  1930  is disposed proximally from the second relay lens  1922 , each aligned along a defined optical axis. This optical assembly  1910  produces an entrance pupil (shown as  1934 ) that is proximate to, but distal relative to the objective lens doublet  1914 , and creating a field of view that enables the entire tympanic membrane to be viewed all at one time at the image plane of the clinician&#39;s eye, if viewed optically, or the image plane of an attached digital imager (not shown). More specifically, this optical assembly  1910  produces a field of view of about 9 mm at a working distance (distance between the distalmost optic and the patient) of about 33 mm, which allows the entire tympanic membrane (about 7 mm) to be viewed all at one time. Though this optical assembly  1910  is highly effective due to the increased field of view, the resulting image is influenced by the attached speculum tip  1124 , as shown in the top illustration of  FIG. 55 . 
     Referring to  FIG. 54( b ) , two other optical assemblies  1940  and  1950  are shown and compared to optical assembly  1910  as well as  FIG. 54( a ) , which illustrates the optical assembly  1900  of instrument head  100 ,  FIG. 2( b ) ,  FIG. 13( b ) . More specifically, the optical assembly  1940  includes in order and arranged from distalmost to proximalmost: an objective lens  1941 , relay lens  1942 , field stop  1945 , imaging lens  1943  and a plano window  1944 . The optical assembly  1950  is similarly defined starting from the distal end and moving toward the proximal end by an objective lens  1967 , relay lens  1968 , a field stop  1971 , an imaging lens doublet  1969  and a plano window  1970 . The optical assembly  1900 ,  FIG. 54( a )  is similar to the optical assembly  1950  and is defined by the following elements from distalmost to proximalmost: an optical window  161  disposed distally relative to an objective lens  160  separated by a field stop  164 ,  FIG. 4 , that reduces light scatter, a relay lens  166 , an aperture plate  167 ,  FIG. 4 , a field stop  170 ,  FIG. 4 , an imaging lens  169  and a window  189  provided at the proximal end of the assembly  1900 . 
     The optical components of each of these optical assemblies  1900 ,  1940 ,  1950  are also configured to create an entrance pupil that is distal from the distalmost optical element  160 / 161 ,  1941 ,  1967 , respectively. 
     The overall effect is shown in the schematic comparative view depicted in  FIG. 55 , contrasting the known optical system  1910  with optical assemblies  1900  and  1950  in which each optical assembly is disposed within the instrument head  1204  for purposes of comparison. A similar field of view is created by each of the optical assemblies  1900 ,  1950 , but the distal entrance pupil  1966  created by each of the latter optical assemblies  1900 ,  1950  is moved distally toward the patient, as compared with that of the distal entrance pupil  1934 . Consequently, the cone of light rays does not chop the attached speculum tip element  1124  and enabling the tympanic membrane to still be viewed all at one time by the caregiver, but without any portion of the speculum tip element  1124  being in the resulting image. 
     Surprisingly and resulting from the above optical system, Applicants have further discovered that the attached speculum tip element can be made optically clear, as opposed to the typical black opaque versions of these elements. The resulting light spot produced is clear, crisp and well defined without edge effects. 
     Another alternative optical assembly  1980  is depicted schematically in  FIG. 56  based on a change in materials that produces a similar overall effect (distal entrance pupil  1966 ,  FIG. 55 ) upon a resulting image of the medical target. In the optical assemblies  1900  and  1950 , each of the optical elements are made from a moldable plastic, while the optical elements according to this latter optical assembly  1980  are made from glass. More specifically, two (2) glass lenses are used in place of a plastic aspheric lens for each of the objective lens  1982 , relay lens  1984  and eyepiece lens  1986  wherein the two glass lenses achieve image quality by two facing plano-convex lenses of high index of refraction (greater than 1.80) and abbe value greater than 35. The optical assembly  1980  further includes a plano window  1988 . It will be understood that similar configurations are possible. 
     Ophthalmoscope 
     The following portion of the description relates to the design of another physical assessment device that is made in accordance with various exemplary embodiments. More specifically, the physical assessment device is an ophthalmic device that is configured for examining the eyes of a patient. It will be understood, however, to those in the field that certain of the inventive aspects described herein can be applied to various other medical examination or diagnostic devices. 
     With reference to  FIGS. 57( a ) and 57( b ) , the ophthalmoscope  2000  includes an instrument head  2004  that is releasably supported to the upper end of a handle or handle portion  2008  using a bayonet or similar connection, the handle portion  2008  enabling the instrument  2000  to be portable and configured for hand-held use. The handle portion  2008  includes at least one contained battery (not shown) for powering a light source (i.e., an LED—not shown) provided in the instrument head  2004 . In addition, a rheostat  2020 , which includes a rotatable portion of the handle portion  2008  is configured to control the amount of illumination of the light source, as well as a depressible on-off button  2022 . The contained battery is preferably rechargeable, wherein the lower portion of the handle portion  2008  includes a charging port  2024 . 
     The instrument head  2004  is defined by a distal (patient) end  2010  and an opposing proximal (caregiver) end  2014 , and further defined by an interior that is sized and configured to retain a plurality of components. As described in greater detail below, the distal end  2010  of the instrument head  2004  receives a deformable eye cup  2030 , while the proximal end  2014  of the instrument head  2004  includes an adapter interface member  2040 , similar to the adapter interface member  180 ,  FIGS. 2( a ) , and  1224 ,  FIG. 30 , to enable releasable attachment of a smart device adapter  300 ,  FIGS. 6-13 ( b ). The instrument  2000  further includes a rotatable diopter wheel  2050  supported between mating front and rear housing sections  2210  and  2214 , as well as an rotatable aperture wheel  2060 , the latter being disposed in a lower portion of the instrument head  2004  and having a portion of the aperture wheel  2050  extending outwardly from a formed slot that is provided in the front housing section  2210 . 
     An optical assembly and an illumination assembly are commonly retained within the interior of the instrument head  2004 . According to this exemplary embodiment and with reference to  FIGS. 58, 59 ( a ) and  59 ( b ), the distal most component of the optical assembly is an objective lens  2240 , which is mounted adjacent the distal end  2010  of the instrument head  2004 . The rear peripheral edge  2242  of the objective lens  2240  is secured against an annular shoulder  2245  formed in the instrument head  2004  and held in position by means of an end cap  2248  that is threadingly positioned onto the distal end of the front housing section  2016 , the latter having a corresponding set of threads  2249 . When secured, the end cap  2248  also is configured to retain a fixation target retainer  2254 , the latter of which is peripherally disposed about the objective lens  2240 . An O-ring  2260  creates a seal between the objective lens  2240  and the fixation target retainer  2254 . 
     Angled slots are provided on a front facing surface of the fixation target retainer  2254  that receive polarizer windows  2256 , (shown only in the exploded  FIG. 58 ) which according to this embodiment can be formed of different colors (i.e., blue, red) for directing a pair of fixation targets to the patient. The polarizer windows  2256  are positioned at the distal (objective) end  2010  of the instrument head  2004  with slots being disposed on diametrically opposite (left/right) sides of the objective lens  2240  where the fixation illumination targets are located. When the patient looks at the fixation target in the opposite direction relative to the eye being examined (that is, the right eye looking at the left target or the left eye looking at the right target), the patient&#39;s eye will align at approximately 17 degrees positioning their optic disc near the center of the view. According to this embodiment, a set of optical fibers (not shown), preferably having polished ends, extend from a contained LED  2356  of the illumination assembly of the ophthalmoscope  2000  to each of the fixation targets. More specifically, the polished distal end of the optical fibers are placed in contact with the polarizer windows  2256 , with the fibers being routed through the interior of the instrument head  2004  upwardly from the LED  2356 , the latter of which is retained in the lower portion of the instrument head  2004 . According to this embodiment, the proximal end of the fixation target fibers are disposed on lateral sides of the LED  2356 , although other suitable configurations can be utilized to direct the required illumination efficiently to the distally disposed fixation targets. 
     The proximal end of the eye cup  2030  is disposed over the distal end  2010  of the instrument head  2204  and about the contained objective lens  2240  to create the proper working distance between the physical assessment device  2000  and the eye of the patient, which according to this embodiment is approximately 25 mm. The eye cup  2030  is made from an elastomeric material and is shaped and configured to allow the distal end of the eye cup to be placed over the eye of the patient. The proximal end of the eye cup  2030  includes at least one internal engagement feature and is shaped to be releasably and securely attached to the end cap  2248 , the latter also being suitably shaped and configured for this engagement. 
     At the proximal end  2014  of the instrument head  2004 , the contained optical assembly includes an eyepiece holder  2270  projecting outwardly (proximally) from the instrument head  2004  and contained within the adapter interface member  2040 . According to this embodiment, the eyepiece holder  2270  is defined by an open-ended structure that retains a pair of eyepiece lenses  2280 ,  2284  each separated an appropriate distance by an intermediate eyepiece spacer  2288 . The eyepiece lenses  2280 ,  2284  are retained proximally relative to a field stop holder  2290  in which the eyepiece holder  2270  is threadingly engaged within an opening formed in the adapter interface member  2040 . A field stop  2297  is retained within a narrowed portion  2299  of the field stop holder  2290 , which is aligned with the eyepiece lenses  2280 ,  2284  and the objective lens  2240  along a defined optical axis of the device  2000 . 
     Disposed between the proximal and distal ends  2010 ,  2014  of the herein described physical assessment device  2200  is a relay lens  2286  that is aligned along the defined viewing axis, as well as an aperture stop  2291 , each of the foregoing optical components being intermediately disposed within the interior of the instrument head  2004  as part of the optical assembly. The relay lens  2286  is retained within a relay lens holder  2287  and more specifically within an aperture that is sized to retain the relay lens  2286  and aligned with the remaining optical components along the defined optical axis. A polarizer window is disposed immediately distal to the supported relay lens  2286 . The relay lens holder  2287  is attached to a proximal end of a top optical base member  2426 . 
     Regarding the illumination assembly and with reference to  FIGS. 58, 59 ( a ) and  59 ( b ), the instrument head  2004  further retains a plurality of components configured for illuminating the patient&#39;s eye. An electrical contact pin  2320  is disposed within a hollow plastic insulator  2328 , the latter having an upper portion which is sized and configured to retain a coil spring  2332  for biasing the contact pin  2320 . The coil spring  2332  is preferably disposed between a top or upper end of the contact pin  2320  and a shoulder formed in an upper portion of the insulator  2328 . 
     When a lowermost end of the contact pin  2320  is engaged with electrical contacts (not shown) in the handle (not shown) of the physical assessment device  2000 , the top end of the contact pin  2320  is pressed into contact with a lower surface of a printed circuit board  2350  for an LED  2356  that is disposed on the upper surface of the circuit board  2350 . The circuit board  2350  is positioned in place onto a circuit board retainer  2330  that further retains the insulator  2328  and contact pin  2320 , the circuit board retainer  2330  having a set of external threads  2331  that engage a set of corresponding threads that are provided within an optical base member  2390 . As discussed herein, the circuit board  2350  can be configured with an LED drive circuit that is compatible with different instrument handles, including those typically configured for driving incandescent light sources. This circuitry is described in a later portion of this application. 
     For purposes of this embodiment, the LED  2356  is aligned with a condenser lens  2364  along a defined illumination axis, the condenser lens  2364  being retained within a lens holder  2380  that is snapfitted in a manner that creates alignment with the LED  2356 . Each of these latter components are further retained within the optical base member  2390 , in which the optical base member  2390  is fitted within a lower necked portion of the instrument head  2004 . 
     According to this embodiment, the aperture wheel  2060  is disposed above the condenser lens  2364  and supported for rotation by the optical base member  2390 . A slot is provided in the front housing section  2016  to permit access to the aperture wheel  2060 , which is configured for rotational movement in order to selectively position each of a series of circumferentially spaced apertures formed on an aperture plate  2404  into alignment with the LED  2356  and condenser lens  2364  along the defined illumination axis. A pair of cover sections  2062 ,  2064  retain the rotatable aperture wheel  2060  within a recessed portion of the optical base member  2390 . The cover portions  2062 ,  2064  retain ends of an axle  2065  that extends through the center of the aperture wheel  2060  and the aperture plate  2404 , enabling rotation. More specifically, a plurality of windows are circumferentially disposed on the aperture wheel  2060  that may include a red free filter, a blue filter, as well as varying sized apertures. Various other configurations can easily be realized. 
     Above the aperture wheel  2060  and the optical base member  2390 , the illumination assembly further includes a relay lens  2420 , which according to this exemplary embodiment is retained within the upper end of the optical base member  2390  and aligned with the condenser lens  2364 , the rotatable aperture wheel  2060 , and the LED  2356  along the defined illumination axis. 
     A polarizer window  2440  is retained at the top surface of the optical base member  2390  above and distally relative to the relay lens  2420  and in relation to a mirror  2450 , the latter being supported by a mirror mount assembly  2453 . A compression spring  2395 ,  FIG. 60( a ) , provided between the top optical base member  2426  and the upper portion of the optical base member  2390  maintains pressure against the polarizer window  2440  and relay lens  2420  of the illumination assembly in which the lower end of the optical base member  2426  is accommodated, but not secured, within an upper portion of the optical base member  2390 . The foregoing arrangement further maintains the alignment of the relay lens  2286  and relay lens holder  2287  of the optical assembly of the herein described device  2000 , each of which are retained within the top optical base member  2426  as previously discussed. 
     With reference to  FIGS. 58, 59 ( b ), and  60 ( a )- 60 ( d ), the mirror mount assembly  2453  includes a elongate mirror mount  2454  having an upper end  2455  and a lower end  2456 . The lower end  2456  of the mirror mount  2454  retains the mirror  2450  along an inclined support surface  2451 . The mirror mount  2454  is pivotally supported within an enclosure  2458  that is provided within the top optical base member  2426 . An adjustment member  2462 , such as a threaded fastener, extends into a formed slot in the rear housing section  2018  of the instrument head  2004  and further extends into an upper section of  2459  of the enclosure  2458 . The distal end of the adjustment member  2462  is configured to engage a rear facing surface  2457  at the top of the mirror mount  2454  in order to cause the mirror mount  2454  to pivot and enable the angle of the supported mirror  2450  to be adjusted to direct light from the LED  2356 ,  FIG. 59( b ) , toward the distal end of the instrument head  2004 . 
     A block  2466  of a elastomeric material, such as poron, is also fitted within the top of the enclosure  2458  immediately adjacent a front facing surface of the mirror mount  2454  against which the adjustment member  2462  engages. With reference to  FIG. 60( c ) , the enclosure  2458  according to this embodiment is defined by a substantially cylindrical upper portion  2459  and a pair of lower extending legs  2460 , the latter which retain the lower end  2456  of the mirror mount  2454  through a pinned connection. The upper end  2459  of the enclosure  2458  includes a threaded sleeve  2461  aligned with the rear facing surface  2457  of the top of the mirror mount  2454  that receives the adjustment member  2462 . The enclosure  2458  according to this embodiment is supported within the top optical base member  2426  along with a sealing member, such as an O-ring  2470 . According to this embodiment, the adjustment member  2462  further permits lateral adjustments of the retained mirror  2450  in addition to angular (pivotal) adjustments of the mirror mount  2454 , wherein the O-ring  2470  contacting the inner surface of the optical base member  2426  provides sufficient resistance to maintain the lateral adjustment of the supported mirror  2450 . 
     Referring to  FIGS. 59( b ) , the illumination assembly allows light from the contained LED  2356  to be directed through the aligned condenser lens  2364 , the aperture wheel  2060 , the relay lens  2420  and the polarizer window  2440  to the supported mirror  2450  along the defined illumination axis. A reticle (not shown) can further be provided as part of the aperture wheel or otherwise within the optical base member. The light is then further directed toward the distal end  2012  of the instrument head  2004  and more specifically through the objective lens  2240  and in which the light is focused at the edge of the pupil of the patient&#39;s eye. The position of the objective lens  2240  can be suitably adjusted at the time of manufacture to further offset any tolerance mismatches in addition to the adjustment of the supported mirror via the mirror mount assembly. 
     Referring to  FIG. 59( a ) , light reflected from the back of the patient&#39;s eye is directed into the distal end of the ophthalmoscope  2000  through the objective lens  2240  in which the light is then focused onto the relay lens  2286 , which directs the light through the field stop  2297  and the imaging lenses  2280 ,  2284  to the clinician&#39;s eye (not shown) or to an attached smart device attached to the adapter interface member  2040 . The adapter interface member  2040  according to this embodiment is structurally similar to the adapter interface member  180 ,  FIGS. 6-13 ( b ), and does not require additional discussion. 
     Variations—Ophthalmoscope 
     As shown in  FIG. 61 , an ophthalmoscope  3100  made in accordance with another exemplary embodiment is herein described. As discussed herein and shown in  FIG. 65 , the ophthalmoscope  3100  includes an instrument head  3104  that is releasably attached to the upper end of a handle portion  3108 . The instrument head  3104  is defined by a distal (patient) end  3112  and an opposing proximal (caregiver) end  3116 . The interior  3105  of the instrument head  3104  is sized and configured for retaining an illumination assembly  3101  and an optical assembly  3102 . 
     According to this version and as shown in  FIGS. 62 and 63 , an eye cup  3120  is attached to the distal end  3112  of the instrument head  3104 . According to this embodiment, the eye cup  3120  is a flexible component, preferably made from an elastomeric material that is designed for direct engagement with the patient. When attached, the eye cup  3120  establishes a working distance between the patient&#39;s eye and a first distalmost lens component of a contained optical assembly. 
     The eye cup  3120  according to this embodiment is defined by a solid contiguous member. In an alternative embodiment, the eye cup can include one or a plurality of slits or openings (not shown) that do not sacrifice structural integrity for purposes of patient alignment. 
     In accordance with an embodiment and as shown in  FIGS. 64( a ) and 64( b ) , a disposable ring member  3124  can be provided which is configured and sized to fit within the distal end opening  3122  of the eye cup  3120 . More specifically, the disposable ring member  3124  is defined by a flexible material, such as, for example, a foam material or polypropylene and defined by opposing distal and proximal end openings  3125 ,  3127  in which the distal end opening  3125  includes an annular outer flange  3129 . When attached, the disposable ring member  3124  can be inserted into the distal end opening  3125  of the eye cup  3120  with the annular outer flange  3129  of the disposable ring member  3124  creating a stop. 
     According to one embodiment, a user can load the disposable ring member  3124  from a stacked set of rings (not shown) in a container (not shown) having an open top and engaging the distal end of the eye cup  3120  with the disposable ring member  3124  until the distal end of the eye cup  3120  engages the annular outer flange  3129  of the disposable ring member  3124 . Compression of the eye cup  3120  creates positive engagement between the inner portions of the eye cup  3120  and the outer surface of the disposable ring member  3124 , allowing the disposable ring member  3124  to remain attached to the eye cup  3120  when the eye cup  3120  is removed from the container. Advantageously, the disposable ring member  3124  can be attached without having to touch the ring member  3124  and wherein the disposable ring member  3124  permits reuse of the eye cup  3120  as shown. The disposable ring member  3124  also serves as a stop, preventing eye cup  3120  from fully compressing against a patient&#39;s eye. 
     With reference to the sectioned view of  FIG. 65 , the instrument head  3104  according to this embodiment is manufactured using a two-part housing made up of a front housing section  3109  and a rear housing section  3110  that are mated together. The instrument head  3104  is defined by an interior  3105  that is sized and configured for retaining a plurality of components, including an optical assembly  3101  and an illumination assembly  3102 . As shown schematically according to  FIGS. 66-68 , the optical assembly  3101  includes a plurality of optical components or elements disposed and aligned along a defined viewing or optical axis  3132  that extends through the eye  3130  of the patient, as well as the distal and proximal ends  3112 ,  3116  of the device  3100 . As previously referred to herein, an “optical component” or “optical element” refers to lenses and prisms as well as field stops, aperture stops, polarizers, and any component used to directing or transmitting light along a defined optical or viewing axis. 
     According to this embodiment, the distal most component of the optical assembly is an objective lens  3140 , which is mounted adjacent the distal end  3112  of the instrument head  3104 . As shown in  FIG. 65 , the rear peripheral edge  3142  of the objective lens  3140  is secured against an annular shoulder  3145  formed in the instrument head  3104  and held in position by means of an end cap  3148  that is threadingly positioned to the distal end  3112  of the instrument head  3104 . When secured, the end cap  3148  also is configured to retain a fixation target retainer  3154 , the latter of which is peripherally disposed about the objective lens  3140  and as further shown in  FIG. 69 . Angled slots are provided on a front facing surface of the fixation target retainer  3154  that receive polarizer windows which according to this embodiment can be formed of different colors (i.e., blue, red) for directing a pair of fixation targets to the patient. 
     As shown in  FIG. 69 , the objective end of the instrument head  3104  is shown with two slots on each side (left/right) of the lens  3140  where the fixation illumination targets are located. When the patient looks at the target in the opposite direction relative to the eye being examined (that is, the right eye looking at the left target or the left eye looking at the right target), the patient&#39;s eye will align at approximately 17 degrees positioning their optic disc near the center of the view. According to this embodiment, a set of optical fibers, preferably having polished ends, extend from the contained LED to each of the fixation targets. More specifically, the polished distal end of the optical fibers are placed in contact with the polarizer windows, with the fibers being routed through the interior of the instrument head and downwardly to the contained LED. According to this embodiment, the proximal end of the fixation target fibers are disposed on lateral sides of the LED, although other configurations can be utilized. 
     The proximal end of the eye cup  3120  is disposed over the distal end  3112  of the instrument head  3104  and about the contained objective lens  3140  to create the proper working distance between the device  3100  and the patient, schematically shown in  FIG. 66 , which according to this embodiment is approximately 25 mm. 
     The proximal end  3116  of the instrument head  3104  includes an eyepiece holder  3170  projecting outwardly (proximally) from the instrument head  3104 . According to this embodiment, the eyepiece holder  3170  is defined by an open-ended structure including an annular shoulder  3172  formed on an outward (proximal) facing side, which is sized and configured to retain a brow rest  3176  for use by the clinician. The eyepiece holder  3170  retains a pair of eyepiece lenses  3180 ,  3184  that are separated an appropriate distance by an eyepiece spacer  3188 . The eyepiece lenses  3180 ,  3184  are retained in a field stop holder  3190  that is threadingly engaged within an opening formed in the eyepiece holder  3170  and the instrument head  3104 . A field stop  3197  is retained within a narrowed portion  3199  of the field stop holder  3190  and aligned with the eyepiece lenses  3180 ,  3184  and the objective lens  3140  along the defined optical axis. 
     Disposed between the proximal and distal ends  3112 ,  3116  of the device  3100  and referring to  FIGS. 65-68 , the herein described optical assembly  3101  further includes a relay lens  3186  that is aligned along the defined viewing axis  3132 , as well as an aperture stop  3191 , each intermediately disposed within the interior  3105  of the instrument head  3104 . 
     The components of the optical assembly  3101  are shown in respective layouts presented according to  FIG. 66-68 , which includes the objective lens  3140 , the aperture stop  3191 , relay lens  3186 , field stop  3197  and eyepiece lenses  3180  and  3184 , each aligned along the viewing axis  3132  relative to the clinician&#39;s eye (not shown) as brought to the brow rest  3176  or as shown in  FIG. 62 , relative to the interface and imaging aperture of an attached smart device  3106 . 
     Regarding the illumination assembly  3102  and with reference to  FIG. 70 , the lower necked portion  3107  of the instrument head  3104  includes a plurality of components configured for illuminating the target (eye) of interest. An electrical contact pin  3220  is disposed within an opening  3224  formed in a plastic insulator  3228 , the latter having an upper portion  3229  that retains a coil spring  3232  for biasing the contact pin  3220 . The spring  3232  is disposed between a top or upper end  3224  of the contact pin  3220  and a shoulder  3238  formed in the upper portion  3229  of the insulator  3228 . 
     When a lowermost end of the contact pin  3220  is engaged with electrical contacts (not shown) in the handle (not shown) of the physical assessment device  3100 , the top end  3224  of the contact pin  3220  is pressed into contact with a lower surface of a printed circuit board  3250  for an LED  3256  that is disposed on the upper surface of the circuit board  3250 , shown most clearly in  FIG. 70 . The circuit board  3250  is positioned in place onto a circuit board retainer  3230  that further retains the insulator  3224  and contact pin  3220 , the retainer  3230  having a set of external threads that engage corresponding threads provided within an assembly support member  3290 . 
     The LED  3256  is aligned with a condenser lens  3264  along an illumination axis  3310 ,  FIG. 66 , the condenser lens  3264  being retained within a lens holder  3280  that further retains a centering ring  3281  aligned with the LED  3256 . Each of these latter components are further retained within the assembly support member  3290 , the assembly support member  3290  being fitted within the lower necked portion  3107 ,  FIGS. 65, 70 , of the instrument head  3104 . 
     Referring to  FIGS. 65 and 70 , an aperture wheel  3300  is disposed above the condenser lens  3264 . The aperture wheel  3300  is supported by the assembly support member  3290  and configured for rotational movement so as to selectively locate and position each of a series of circumferentially spaced apertures formed on an aperture plate  3304  into alignment with the LED  3256  and condenser lens  3264  along the defined illumination axis  3310 ,  FIG. 67 . More specifically, a plurality of windows  3304  are circumferentially disposed on the aperture wheel  3300  that include a red free filter, a blue filter, as well as varying sized apertures. It will be readily apparent that various other configurations can easily be realized. 
     With reference to  FIGS. 65 and 67  and above the aperture wheel  3300  and the assembly support member  3290 , the illumination assembly further includes a relay lens  3320  which according to this embodiment is retained in a holder  3326 . According to this embodiment, the relay lens holder  3326  is threadingly secured to an upper portion of the assembly support member  3290  and aligned with the condenser lens  3264 , aperture wheel  3300 , and the LED  3256  along the defined illumination axis  3310 . 
     With reference to  FIGS. 66-68 , the optical and illumination assembly components of this physical assessment instrument are illustrated in schematic form for the sake of clarity. As noted, the optical assembly  3101  includes the objective lens  3140  aligned with eyepiece lenses  3180 ,  3184  and the field stop  3197 , as well as the relay lens  3186  and the aperture stop  3191 , each of which are aligned along the defined optical axis  3132 . In addition, a diopter wheel  3200  supports a plurality of optical elements  3204  of varying power (concave/convex). The diopter wheel  3200  is rotatably movable into and out of the defined viewing axis  3132  for purposes of establishing the focus of the patient&#39;s eye  3130 . 
     Still referring to  FIG. 67 , the illumination assembly  3102  comprises the LED  3256  aligned along the defined illumination axis with the condenser lens  3264  and the rotatable aperture wheel  3300 , as well as the illumination relay lens  3320 , each disposed in alignment with an angled mirror  3350 , the latter being offset relative to the imaging axis  3132 . 
     In accordance with this embodiment and referring to  FIGS. 71( a ) and 71( b ) , the mirror support member  3354  can be threadingly fitted into a formed port at the top of the instrument head  3104 . A mirror  3350  is attached to a pivotable portion  3360  which can be accessed and enables adjustment during the time of manufacture. According to one version, the mirror  3350  can be adjusted using and adjustment member  3352  that is accessible through a port formed in the rear of the instrument head  3104 . The mirror  3350  is further attached to a movable member that enables additional adjustment of the supported mirror  3350 , as needed. The mirror mount assembly described is exemplary. For example, the mirror mount assembly  2453  described in the prior embodiment (see  FIGS. 60( a )-60( f ) ) can be substituted for this version. 
     For purposes of this embodiment, the illumination assembly  3101  utilizes a single LED  3256 , though the number and color temperature of the LED can be suitably varied. According to this embodiment, a magnification lens  3210  is provided adjacent a window of the necked portion  3107  in order to permit a caregiver to more easily read the diopter wheel setting of the herein described ophthalmic device  3100 . 
       FIG. 67  illustrates an illumination ray trace of the herein described instrument  3100 . According to this embodiment and upon engagement between the lower end of the contact pin with the contained battery (not shown) in the instrument handle (not shown), the contained LED  3256  is energized. The output of the LED  3256  is directed through the centering ring  3251 , the condenser lens  3260  and the aperture wheel  3300  along the defined illumination axis  3310  in which the beam passes through the relay lens  3320  and a polarizer  3340  and is directed against the folded mirror  3350 , whose position is adjusted at the time of manufacture within the mirror mount by accessing a threaded adjustment member. 
     Though the imaging elements of the assembly are also shown in this view, the light does not cross the imaging axis  3132 . In addition and also not shown, a portion of the emitted light is directed through a set of optical fibers (not shown) through the instrument head  3104  and to the fixation targets positioned at the distal end  3112 . 
     Still referring to  FIG. 67 , the emitted light from the LED  3256  is reflected from the angled mirror  3350 , the latter having an angled surface that directs the light toward the distal end  3112  of the instrument head  3104  and more specifically through the objective lens  3140 . The reflected light passes through the objective lens  3140  and is then focused onto the eye  3130  of the patient. According to this embodiment, the focal point of the reflected light is off center relative to the front of the eye  3130  of the patient and more specifically the pupil serving as the image plane wherein the light is then spread outward onto the back of the eye and more specifically the retina  3137 . As shown and described herein, the focused spot is off-line relative to the optical axis  3132  of the device  3100 . 
     With reference to  FIGS. 66 and 68 , the imaging of the target (i.e., the retina  3137 ) is reflected from the back of the eye  3130  to the objective lens  3140  in which the light is further directed along the defined optical axis  3132  through the image aperture plate  3188  in which an inverted image is passed. The light is then directed to the relay lens  3186 , field stop  3197  and through the eyepiece lenses  3180 ,  3184 , respectively, wherein the light is focused onto the eye (not shown) of the caregiver as an erect image. 
     Alternatively and in lieu of the eyepiece, the light can be directed through the aperture of a smart device  3106 ,  FIG. 62 , such as a smart phone, which is attached to the proximal end  3116  of the device  3100  and aligned in relation to the optical axis  3132 . This attachment can be done in the manner previously described according to  FIGS. 6-13 ( b ) or the alternative techniques described in  FIGS. 14-20 . 
       FIG. 73  illustrates an optical layout illustrating scaling for instrument heads  3404 ,  3414 , such as shown in  FIG. 74 . More specifically, the instrument heads  3404 ,  3414  can include scaled optical assemblies maintaining back ends that commonly include relay lenses  3440 ,  3444  and eyepiece lenses  3448 , while axially adjusting the position and dimensionally scaling the objective lens  3424 ,  3434  and aperture plate  3427 ,  3437 , the latter enabling common interfaces for various physical assessment devices. 
     A benefit of the optics of the illumination assembly is depicted in  FIG. 75 . At the top of the figure is a known ophthalmic illumination assembly in which the positioning of the condensing lens in which the focus distance creates a potential issue in which dirt or debris on the condensing lens can interfere with the resulting examination. The lower portion of the figure indicates a point focus relative to the front and back surface of the condensing lens that effectively removes this issue, while maintaining a reticle plan focus at infinity. 
     A general need in the field of diagnostic medicine is that of enhancing versatility and interchangeability between physical assessment devices, such as, for example, otoscopes and ophthalmoscopes. According to one example, depicted in  FIGS. 76( a ) and 76( b ) , ophthalmoscopes can be reconfigured in order to permit examinations of eye of a patient. The depicted ophthalmoscopes  3450 ,  3470  in these figures are those of Model 117 Ophthalmoscope and Model 12800 Pocket Ophthalmoscopes, respectively, each commercially sold by Welch Allyn, Inc of Skaneateles Falls, N.Y. In accordance with this exemplary embodiment, each of the instrument heads  3454 ,  3474  are configured to permit otoscopic examinations. More specifically, a tip attaching and releasing mechanism is fitted into the distal end  3456 ,  3476  of each ophthalmoscope  3450 ,  3470  to enable the releasable retention of a disposable speculum tip element  120  at the distal end as a patient interface, in lieu of an eye cup. For purposes of this conversion, each existing instrument head  3450 ,  3470  can be configured with a distal insertion portion and distal ring member similar to that included in the previously described otoscope  100 ,  FIG. 2( b ) . 
     In use and for purposes of close-up viewing, the existing diopter wheel  3462 ,  3482  of each ophthalmoscope  3450 ,  3470  can be used to provide accommodation at a setting of approximately 10-15 diopters, based on the caregiver&#39;s personal vision and the application/use. Each are accomplished using the rotatable diopter wheel common to the known ophthalmoscopes. 
     According to a further version, the speculum tip attachment mechanism can be installed onto the distal end  3456 ,  3476  of the instrument head  3452 ,  3472  in order to preset the angle of the attached tip element  120  relative to the contained light source. Advantageously, this preset positioning of the attached speculum tip can optimize uniformity and concentricity of the illuminated light from the contained light source in the handle portion of each of the depicted instruments  3450 ,  3470 . 
     LED Drive Circuitry 
     Current instrument heads, such as those commercially sold by Welch Allyn, Inc. are wholly halogen lamp based. Electrically, the lamp filament is a piece of wire whose resistance increases with temperature. So, for any given input voltage, the filament heats up which increases its resistance until the drive circuit reaches a natural equilibrium (heat/light/resistance/current for the given input voltage). When the input voltage is raised, the lamp filament becomes brighter and when the input voltage is lowered the lamp filament dims. 
     Contrasting, all known LED controller ICs in the electronics industry are designed to ignore its input voltage. This is done for a number of valid reasons, but the crucial point is that by definition, a system that varies voltage as a way of controlling light output is categorically incompatible with LED technology. Therefore, it is not recommended to vary/dim LED brightness by changing its input voltage. With the incorporation of both light sources into instrument heads, a solution is needed for driving and dimming both halogen lamps and LEDs. 
     Accordingly,  FIGS. 77-81  describe an exemplary embodiment of circuitry for controlling LED lighting in an instrument head. The embodiments disclosed herein provide numerous enhancements over conventional lighting control circuits. For instance, typical instrument heads are only compatible with specific instrument handles, because the instrument handles provide electrical power to the instrument head, and must provide that electrical power in a very specific profile of voltage and current. Thus, instrument heads are not typically usable with different instrument handles, requiring a proliferation of instrument heads and designs. 
     For instance, different types of lighting have different electrical properties. For example, LED light dimming may be achieved by constant voltage, and thus a constant current, that is pulse-width modulated to reduce the duty time that the LED is on, whereas incandescent light dimming may be achieved by changing voltages. In addition, traditional instrument heads may include alternating current (AC) power sources, and may only be compatible with lighting that can use AC power, such as incandescent or halogen lighting. Further, different instrument handles may be wired with different polarities, requiring the instrument heads to be hardwired to accept the specific polarity. In addition, LEDs and LED drive circuits have strict requirements for polarity. Current instrument handles have multiple polarities (+/−, −/+ and a variation of AC), and therefore the input power must be rectified to a single polarity before an LED in the instrument head can be driven. 
     Advantageously, the circuits disclosed herein are designed to solve these problems by allowing compatibility between different instrument heads and instrument handles. 
       FIG. 77  depicts a block diagram of a circuit  3510  for controlling or driving LED lighting. The circuit  3510  may be disposed within an instrument head, such as the instrument head  104  of the otoscope of  FIGS. 1( a ) - 5  or the instrument head  2004  of the ophthalmoscope of  FIG. 59( b ) , which provides power and has buttons for controlling the lighting, including turning on or off, dimming, brightening, etc. The circuit  3510  includes a controller  3514 , a buck/boost or power circuit  3516 , and a rectifier circuit  3518 . The circuit  3510  may be connected to an instrument handle  3512 , and such connection may be through a 2-wire connection, 3-wire connection, or any other suitable connection having multiple wires for voltages and/or signals. Working examples of specific implementations of the controller  3514 , the power circuit  3516 , and the rectifier circuit  3518  are discussed below with respect to  FIGS. 79-81 . 
       FIG. 78  is a flowchart depicting a method  3500  for controlling LED lighting in an instrument head, by using the circuit  3510  of  FIG. 77 . With reference to  FIGS. 77-78 , in one example, at block  3520  an instrument handle  3512  may be connected to an instrument head, such as the instrument head  104  of the otoscope of  FIGS. 1( a ) - 5  or the instrument head  2004  of the ophthalmoscope of  FIG. 59( b ) , where the instrument head includes the circuit  3510 . This connection may be through a 2-wire, 3-wire, or other suitable connection. In one example, simple 2-wire connection would only allow the instrument handle  3512  to provide electrical power (e.g., at specific voltages and currents) to the circuit  3510 . In another example, the instrument head may include one or more wires with a control signal, such as a serial port, for sending control signals from the instrument handle  3512  to the circuit  3510 . The signals received by the circuit  3510  from the instrument handle  3512  may be an AC voltage or a DC voltage signal having varying levels of voltage and/or current. 
     Based on the signals received by the circuit  3510  from the instrument handle  3512 , at block  3530  the power profile of the instrument handle  3512  may be determined. For instance, the controller  3514  of the circuit  3510  may be programmed to sense the voltage, current, polarity, and other signals from the instrument handle  3512 , and use this information to determine what type of instrument handle is in fact connected. 
     For example, conventional instrument handles may be designed to use voltage change to control dimming of halogen or other incandescent lamps. In such a case, electrically, the lamp filament is a piece of wire whose resistance increases with temperature. So, for any given input voltage, the filament heats up which increases its resistance until the drive circuit reaches a natural equilibrium (heat/light/resistance/current for the given input voltage). When the input voltage is raised, the lamp filament becomes brighter and when the input voltage is lowered the lamp filament dims. Contrasting, all LED controller ICs in the electronics industry are designed to ignore its input voltage. This is done for a number of valid reasons, but the crucial point is that by definition, a system that varies voltage as a way of controlling light output is incompatible with LED technology. Therefore, it is not recommended to vary/dim LED brightness by changing its input voltage. With the incorporation of both light sources into instrument heads, the present circuit  3510  allows for driving both LED and incandescent light sources from a single instrument handle  3512 . Thus, the controller  3514  could sense the properties described above and make a determination that the instrument handle connected is of a type typically used to drive halogen or other incandescent lamps, but that this instrument handle now needs to drive LED lighting. 
     Continuing with method  3500  of  FIG. 78 , at block  3540 , the circuit  3510  may be configured for operation at the power profile determined at block  3530 . This configuration may include configuring the controller  3514  and/or the power circuit  3516 , as explained in further detail below with respect to  FIGS. 79-81 . 
     Advantageously, configuring the circuit  3510  for operation with the instrument handle  3512 , based upon auto-detection of the handle profile, allows any number of different instrument handles that have been deployed in the field to be used with the new instrument heads described herein. Thus, the benefits of the features, such as LED lighting, may be realized even without replacing these previously deployed instrument handles. This auto-detection and configuration of instrument heads for use with instrument handles represent improves the field of medical devices, because the technique allows mixing and matching of different handles and heads by the clinician or other caregiver, increasing efficiency with which patients may be treated. 
     Next, at block  3550 , the LED lighting of the instrument handle, which is driven by the power circuit  3516 , may be operated and controlled using the instrument handle  3512 . In order to facilitate operating and controlling the LED lighting with different instrument handles  3512  that may have very different electrical profiles, the power circuit  3516  includes buck-boost voltage conversion that allow variable input voltages to be converted into a specified output voltage, where the input voltages may be above or below the specified output voltages. The buck portion of power circuit  3516  decreases a higher input voltage to meet the requirements of a lower specified output voltage, and the boost portion of power circuit  3516  increases a lower input voltage to meet the requirements of a higher specified output voltage. Specific details of this power circuit  3516  is set forth with respect to  FIG. 80 . In addition, operating and controlling (at block  3550 ) the LED lighting with the instrument handle  3512  is also achieved by converting changes in voltage to changes in current, as will be described in more detail with respect to  FIGS. 79-81 . 
     Further, at block  3560  of the method  3500 , the controller  3514  can detect an idle state of the instrument handle. Upon detection of an idle state, the instrument head can be powered off. And, at block  3570 , the controller  3514  can detect a vibration state of the instrument handle, and can perform a specific action based on that state, such as powering off the instrument head. 
     Another problem identified with portable physical assessment devices is that of theft of the instrument handles from the charging base. Using the controller  3514  to detect state changes, a theft deterrent mechanism that could be included. For example, an audible alarm could be set off from the charging base if the instrument handle is not returned in a predetermined time interval. In addition, an LED indicator can also be provided on the charging base when the alarm feature is enabled. 
     An electrical circuit design can provide a controller that generates an audible alarm if the instrument handle is not returned to the charging base, such as base  1800 ,  FIG. 52 , in a defined amount of time. 
     In another embodiment, an auto-off feature will turn off the instrument after a predetermined time period of inactivity. In such an example, the controller is programmed with a timer. If a motion sensor subsystem that is connected to the controller fails to report any motion during the time period, as counted by the timer, the system will turn off the instrument. 
       FIG. 79  is a circuit diagram of the controller  3514  and affiliated circuitry. In the embodiment of  FIG. 79  the controller  3514  may be a model CY8C4025LQI-S401 microcontroller available from Cypress Semiconductor Corporation, of San Jose, Calif., USA. In other embodiments, discrete logic elements may be employed instead of a microcontroller. 
     As shown in  FIG. 79 , the controller  3514  is connected to the input voltage that has passed through the rectifier of  FIG. 81 . The rectifier is needed because the LEDs may be powered by direct current rather than alternating current. The rectified voltage then is input into the controller  3514 , which then outputs a pulse width modulation signal LED_PWM. The LED_PWM signal is input into the buck/boost or power circuit  3516 , as depicted in  FIG. 81 . Any of a number of PWM algorithms may be used with the circuit. For instance, in traditional voltage based dimming, a voltage vs. brightness curve may be described that relates a given voltage to a given brightness. A linear relation would mean that if the voltage is reduced by 50% from a nominal high voltage, the brightness would reduce by 50%. In order to translate this into dimming an LED, a PWM signal that is on for 50% of the time would power an LED half the time and thus achieve 50% brightness. 
     In other embodiments, a non-linear relationship between the voltage an brightness may be observed. In one example, a calibration of a legacy handle and legacy incandescent head can be carried out, so that the legacy handle can later be used with a new head of the present disclosure. For example, the calibration process could use the legacy handle connected to the legacy incandescent head, and the legacy handle&#39;s voltage may be varied from maximum to minimum while measuring the brightness percentage as a function of voltage. The resulting calibration data set relates voltage to expected brightness percentage for the legacy handle. This calibration curve can be loaded into the controller on an instrument head of the present disclosure so that the brightness control of the legacy handle will have the same effective result when using the new instrument head. 
     The controller would achieve this by detecting the input voltage from the handle, and using a lookup table containing the calibration data set to find the appropriate desired brightness percentage. Then, instead of applying the input voltage to the LED, the input voltage would be buck/boost converted to yield a constant LED current. The brightness would be controlled by a PWM signal that turned on and off the LED such that the LED was on for the desired brightness percentage of the time, and off the rest of the time. In such a manner, numerous different legacy handles with different voltages can be profiled to find calibration data for use in the instrument head described herein. 
     In an embodiment, the controller  3514  receives the input voltage VIN from the instrument handle and determines its polarity. Depending on the polarity of the voltage VIN received from the instrument handle, and potentially other indicia such as power on signals, initial voltage, etc., the controller can determine the power profile for that specific instrument handle, e.g., by using a lookup table that lists all the known instrument handles and their known polarities, initial voltages, power on signals, etc. In such a case, the controller can determine what type of instrument handle has been attached, and then can access the voltage calibration curve of the instrument handle, which relates the voltage to the output illumination level of the LED as explained above. The LED_PWM signal from the controller may the appropriately drive a PWM signal of the correct duty cycle (e.g., percentage on to off) to achieve the brightness of the LED that corresponds to the brightness that an incandescent instrument head would output if the same instrument head were connected to it and directly driven using the voltages. In such a manner, the input voltages changes have been converted to PWM signals of specific duty cycles of a constant current that can be used to power and dim an LED. In another example, specific pins on the instrument handle may carry identification or handshake data that tells the instrument head which handle has been connected, allowing the controller to lookup a pre-loaded power profile for that handle. 
     In an embodiment, the controller  3514  may also determine vibration/motion or idle states of the instrument head and/or handle, and perform appropriate actions as described with respect to method  3500  above. In one example, idle states can be determined by a lack of motion sensor indicated activity during a predetermined time period, and the action can be to shut off the instrument. In another example, motion of the instrument can be detected by the motion sensor, and an idle timer can be reset, or other subsystems may be turned on. 
       FIG. 80  is a circuit diagram of the buck/boost or power circuit  3516 . In the example of  FIG. 80 , the power circuit  3516  is based on a TPS63036 Buck/Boost converter U 5  with support for receiving the LED_PWM signals from the controller as described above. The TPS63036 is available from Texas Instruments Inc., Dallas, Tex., USA. In the circuit diagram of  FIG. 80 , we see that the input voltage is fed into the converter U 5 , which is also controlled using the EN and PWM_LED signal from the controller  3514 , in order to apply the PWM profile to dim the LED lighting as noted above with respect to  FIG. 79 . 
     In operation, the buck/boost or power circuit  3516  may receive the input voltage VIN and provide an output voltage VOUT that generates a fixed or constant current for powering the LED lights. The output voltage VOUT may be tuned by appropriately setting resistors R 1  and R 2 , in the specific example using a TPS63036 converter. Once set up, the buck/boost or power circuit  3516  would output the fixed or constant current for powering the LEDS, and the PWM_LED wire from the controller  3514  would be used to provide the PWM signal with the appropriate duty cycle for achieving a specific brightness. In other examples, the buck and boost portions of the circuit may be implemented separately using discrete components instead of a single buck/boost converter. In such a case, the circuit would boost a VIN that was less than VOUT through a boosting sub-circuit, and decrease or buck a VIN that was greater than VOUT through a buck sub-circuit. 
       FIG. 81  is a circuit diagram of the FET full-wave bridge circuit  3518 . Rectification to a single polarity is typically done with a diode Full Wave Bridge (FWB). Diode FWB&#39;s typically lose between 1V and 1.4V in the rectification process. This is a considerable proportion of the LED voltage, which is typically 2.7V. That ratio approximates the loss of energy from the battery never to produce light. In order to minimize losses associated with a diode full-wave-bridge, a FET full-wave-bridge is introduced, as shown in  FIG. 81 . The FET FWB design only loses about 50 mV, depending upon the current and FETs selected. The energy not lost means energy available to produce light and increasing overall battery life of the device. 
     The FET FWB circuit design is made up of two NFETs, two PFETs, and the necessary capacitors. The FET full-wave-bridge has considerable ESD protection, mostly realized in capacitors across the gate-source for each FET. 
     In accordance with another embodiment and with reference to  FIG. 82 , an instrument head for a physical assessment device is configured with a buck convertor head design, which is an LED controller circuit design that will drive an LED effectively and without risk of instability (LED Flicker) with a PWM (Bang-Bang) power source. 
     For the power source, a traditional RC hysteretic oscillator (nicknamed bang-bang in the electronics world) will be used. This power source will drive both a halogen lamp head and the LED instrument head having the buck converter. For the buck converter LED driver head, and while the input voltage is sufficient, there is controlled brightness. For output voltage varying power sources (as the drive voltage lowers (dimming)), the buck converter eventually runs out of headroom and the LED is driven directly by the driving voltage (in series with the parasitic resistances of the controller and the mechanical system). This occurs when V in  approaches the LED&#39;s VF plus the controller&#39;s sense voltage plus the parasitic IR losses. For a PWM power source, as long as the output voltage is greater than the LED&#39;s VF, the bang-bang dimming will dim the LED effectively and without instability (flicker). For purposes of this specific embodiment, the circuit is the PAM2804 IC LED driver applied as the manufacturer recommends. The PAM2804 is a suitable example of an LED Driver IC since it will run down to the appropriate voltage of 2.5V. This is an anomaly because no high brightness LED has a forward voltage of 2.5V. The 2.5V capable DC-DC converter IC, PAM2312-ADJ, can be repurposed for LED drive by lowering its reference voltage from 0.6V to 0.1V. 
     An alternative drive circuit is shown in  FIG. 83  in which R 25 , R 26  and R 27  are additionally provided to enable fine tuning in order to adjust the LED effective forward voltage. This capability enables a number of LEDs to operate in a representative manner across instrument heads and handles. 
     LED&#39;s and LED drive circuits have strict requirements for polarity. Current instrument handles have multiple polarities (+/−, −/+ and a variation of AC), and therefore the input power must be rectified to a single polarity before an LED in the instrument head can be driven. 
     Rectification to a single polarity is typically done with a diode Full Wave Bridge (FWB). Diode FWB&#39;s typically lose between 1V and 1.4V in the rectification process. This is a considerable proportion of the LED voltage, which is typically 2.7V. That ratio approximates the loss of energy from the battery never to produce light. In order to minimize losses associated with a diode full-wave-bridge, a FET full-wave-bridge is introduced, as shown in  FIG. 82 . The FET FWB design only loses about 50 mV, depending upon the current and FETs selected. The energy not lost means energy available to produce light and increasing overall battery life of the device. 
     The FET FWB circuit design is made up of two NFETs, two PFETs, and the necessary capacitors. The FET full-wave-bridge has considerable ESD protection, mostly realized in capacitors across the gate-source for each FET. 
     While a 2-wire voltage varying input is the standard method for adjusting brightness for a halogen or incandescent lamp, it&#39;s problematic for LED circuits as has happened in the commercial and residential lighting industry. The most significant issue is loop stability going unstable, causing LED&#39;s to blink. This can be a serious problem in physical assessment devices such as ophthalmoscopes, otoscopes, etc. Industry LED circuits rely upon pulse width modulation for dimming LEDs. In order to drive both an LED and halogen based lamp from a single voltage varying power source an electrical solution must be designed. 
     The herein described electrical circuit design shown in  FIGS. 83( a ), 83( b )  will drive both an LED and halogen based lamp from a single varying power source and maintain loop stability so that there is no risk of blinking LEDs. 
     This electrical circuit design works when first energized, the output of the comparator is low, turning on the PFET. Assuming the LED voltage to approximate a constant, the voltage across the Power Inductor will approximate a constant. As such, current will rise at a linear rate. This causes a positive slope voltage ramp across the sense resistor. For purposes of this circuit, this sense voltage is “faked” low at the positive input of the comparator by the voltage divider (ratio Hyst Res/(hyst Res×FeedBack Res). When this comparator positive input voltage reaches VREF, the comparator output goes high, turning off the PFET. This is called the “Upper Threshold” of the hysteresis circuit. This output swing instantaneously reverses the voltage divider, faking the sense current high instead of low at the positive input to the comparator. As such, the current must go to the Lower Threshold of a hysteresis circuit before it crosses+VREF before the output will again go low. While the PFET is turned off (comparator output high), current continues to flow through the inductor, through the catch diode, causing a negative slope across the sense resistor. 
     When the current reaches the lower threshold, the output goes low, turning on the FET and the cycle continues. Since the sense voltage ramp is nearly linear both up and down, the average current will be the +VREF/SENSE RESISTOR. In other words, given a triangle wave, there will be half the area above and below its average. The circuit is regulated and controlled. The only drawback is high ripple current, but this doesn&#39;t matter for a LED, especially since practical frequencies are far above what the human eye can detect. More so, increasing the output capacitor (C 17 ) of the hysteretic current source will reduce the ripple current and make the slopes more linear. Of more importance though, is that there is no high gain closed loop most often used in power supply control circuits, including LED drivers. Since the oscillation is no more than an inductor being charged and discharged while banging into two predictable thresholds, the instability of the oscillator cycle eliminates the chance of subharmonic oscillations that traditional controllers are prone to. In other words, the connected LEDs will not be prone to blinking. 
     This described circuit is stable. This circuit also does not dim with input voltage so no advantage is otherwise over traditional LED driver circuits. However, and if the reference voltage is varied as a function of input voltage (something that cannot be done with traditional power supply—including LED controllers—control loops without risking instability), the LED current will vary as a function of input voltage. Unlike high-gain control loops which vary many of their stability parameters with input voltage and reference voltage changes, the hysteretic controller continues to bang between the upper and lower thresholds and the average is the reference voltage. The addition of a voltage divider to create+VREF and the LED voltage will vary proportionally to +VIN. 
     As previously discussed, another problem identified with portable physical assessment devices that require base charging is that of theft of the instrument handles from the charging base. Another object of the herein described invention is to provide a theft deterrent mechanism that would be included in the charging base. 
     Such theft detection could include an audible alarm from the charging base if the instrument handle is not returned in a predetermined time interval. In addition, an LED indicator can also be provided on the charging base when the alarm feature is enabled. 
     An electrical circuit design can provide a controller that generates an audible alarm if the instrument handle is not returned to the charging base, such as base  1800 ,  FIG. 52 , in a defined amount of time. According to one version, there are four (4) pogo pins provided in the charging base; a positive contact, two negative contacts, and one contact for instrument handle detection. This handle detection contact would be what triggers the time period once the instrument handle is removed and stop the timer once the handle is placed back into the charging base. In addition, an LED indicator on the charging base can be illuminated to alert individuals that the theft alarm is enabled. This LED indicator would flash/blink when the audible alarm is sounded. A switch can be provided on the bottom or otherwise upon the charging base to enable/disable the alarm feature. This switch could be recessed in the housing of the charging base and be made only accessible by a specialized tool or other access feature, such as small piece of metal (e.g., a paper clip). There may also be some other type of switch to set the defined time for the alarm to enable once the handle is removed. 
     Capturing Images with Minimal Defects and/or Artifacts 
     Conventional instrument heads are either wholly halogen lamp based or make use of LED lights that are dimmed using pulse width modulation (PWM) in which the LED is rapidly switched on and off. The speed with which the LEDs are switched on and off is so rapid that the human eye perceives constant illumination at a lower brightness level, and does not sense that the LED is ever fully turned off. By contrast, imaging equipment, including stand-alone cameras and smart phones, operate at a speed much faster than the human eye. If imaging equipment is used to capture images through an instrument which uses PWM dimmed LED lighting, under certain circumstances image defects and artifacts appear when the imaging equipment attempts to capture an image during an off-cycle of the PWM dimmed LED lighting. These defects and artifacts can appear under various circumstances, but generally are caused by the capture device trying to capture an image with insufficient illumination. 
     Indeed, modern imaging equipment, such as that used in smart phones, can use a digital technique that serially generates an image from top to bottom or left to right. During such a scan, which takes a specific period of time, if the PWM LED lighting cycles from on to off (one or more times) certain image areas will be captured as completely dark. The resulting image will thus include certain dark bands, leading to a striped light/dark pattern in the image which will obscure details of the anatomy being examined. For instance, a retinal scan will include striped patterns, and the resulting images will be useless for diagnosis. 
     For example,  FIG. 87  depicts PWM dimming of a drive circuit driving an LED light with a waveform  8700 . As depicted in  FIG. 87 , waveform  8700  oscillates between on and off at with a frequency of 544.7 Hertz. During the on-cycle, the circuit delivers current to the LED light. Conversely, during the off-cycle, no current is delivered to the LED light. Such a waveform  8700  leads to the illumination of the LED light being dimmed. 
     However,  FIGS. 87A and 87B  depict images that include artifacts when the illumination is dimmed using PWM dimming.  FIG. 88A  depicts an image  8800 A of a medical target. As seen in  FIG. 88A , dark bands  8805  run vertically through the image, and are artifacts of PWM dimming that obscure the image  8800 A. Additionally, the illumination can create interference as a result of reflections and interaction with the cell phone image capture software as seen in  FIG. 88B , which is an image  8800 B of a medical target, such as a retina. Image  8800 B includes artifacts  8810  when dimmed using the PWM dimming of  FIG. 87 . These artifacts appear as dark bands which obscure the medical target and in some cases can cause the image capture device to be unable to focus and capture the images. Without wishing to be limited or bound by theory, Applicant believes that these artifacts are caused by the serial digitization of the image by the capture devices, such that subsequent rows of the image are being digitized during the off-cycle of the PWM waveform  8700  and the image processing capability of the image capture device. 
       FIG. 89  depicts one example of a drive circuit  8900  for capturing images of medical targets free of artifacts in accordance with an embodiment. As may be seen in  FIG. 91 , the substantially triangle waveform  9100  slowly declines towards zero, instead of sharply reaching zero like the PWM waveform  8700  of  FIG. 87 . This allows the LED light to have some illumination of the medical target throughout the duty cycle, ensuring that when the camera captures an image, there is enough illumination to avoid artifacts. 
     Circuit  8900  includes: a comparator U 1 , e.g., model MCP6541UT-E/OT available from Microchip Technology of Chandler, Ariz., USA; a P-channel MOSFET Q 1 , e.g., model SI2301BDS-T1 available from Siliconix, San Jose, Calif., USA; and the following discrete components: resistors R 1  (150 kilo-ohm), R 2  (1 mega-ohm), R 3  (33.2 kilo-ohm), R 4  (54.9 kilo-ohm), R 5  (100 ohm), R 6  (1.8 kilo-ohm), RP 1  (100 kilo-ohm), and capacitor C 2  (470 pico-farad). In circuit  8900 , capacitor C 2  and resistor R 4  (which impact the time constant), gate driver resistor R 5  and U 1  are selected so that the drive circuit  8900  outputs a pulse width modulation (PWM) with a frequency selected to illuminate an LED such that the frequency is sufficiently fast such that the output to the LED never fully turns off and ensures that the image is illuminated with no more than some modulation during the time it takes for a smart phone camera to capture an image. 
     For instance, the drive circuit  8900  may be tuned with selected capacitor C 2  and resistor R 5  to output a PWM waveform  8900  that operates at a frequency with a period two, three or more times the time constant of the attached circuit or device to be illuminated, ensuring sufficient illumination to avoid defects. 
       FIG. 90  depicts another example of a drive circuit  9000  which produces a constant regulated current to an LED. The digital parameters of drive circuit  9000  are converted to analog. Circuit  9000  includes a buck-boost driver U 5 , e.g., model TPS6303X available from Texas Instruments, Dallas, Tex., USA; low-dropout regulator U 7 ; MOSFET Q 4 , e.g., model SI1022 available from Sliconix; resistors R 1  (4.99 kilo-ohm), R 2  (15 kilo-ohm), R 28  (2 ohm), R 36  (1 kilo-ohm), R 37  (10 kilo-ohm), R 39  (2 ohm), R 42  (24.3 kilo-ohm), R 49  (100 kilo-ohm), R 50  (10 kilo-ohm); capacitors C 11  (100 nano farad), C 12  (10 micro farad), C 15  (4.7 micro farad), C 16  (10 micro farad), C 26  (10 micro farad), C 30  (100 nano farad); and inductor L 1  (1.5 micro henry). For instance, the drive circuit  9000  may be tuned by selecting resistor R 37 , capacitor C 26 , and driver U 5 , in order to change the PWM input to a generally analog feedback signal to U 5 . U 5  then regulates the output to the LED as a constant current. 
       FIG. 92  depicts an example of capturing an image  9200  of medical target free of artifacts using either the drive circuit  8900  ( FIG. 89 ) or the drive circuit  9000  ( FIG. 90 ). As may be seen when comparing  FIG. 92  with  FIG. 88 , the artifacts  8810  have been eliminated so that all of the details, such as blood vessels, of the medical target are visible. Of course, in other examples, the medical target may be any of the different types of targets described herein. 
     By way of summary,  FIGS. 87-92  describe, in one embodiment, a physical assessment device. For instance, the physical assessment device includes an instrument head, an optical assembly and an adapter interface member. The instrument head has a distal end, an opposing proximal end and an interior. The instrument head includes an illumination assembly including at least one LED and a drive circuit for powering the at least one LED with a pulse width modulation (PWM) current to achieve a variable brightness of the at least one LED. The optical assembly is disposed within the instrument head and includes a plurality of optical components disposed along an optical axis. The adapter interface member is disposed at the proximal end of the instrument head, and enables an image capture device to be attached to the instrument head and aligned with the optical axis. The image capture device is configured to capture images of medical targets when illuminated by the at least one LED with the variable brightness. The drive circuit is coordinated with the image capture device to ensure that the medical targets are at least partially illuminated during the capturing of the images notwithstanding the variable brightness of the at least one LED being achieved using the PWM current. In one example, the drive circuit is coordinated with the image capture device to ensure that the medical targets are at least partially illuminated during the capturing of the images by selecting a frequency of a duty cycle of the drive circuit to include at least two on-cycles of the PWM current to overlap with an image scanning period of the image capture device. In another example, the drive circuit is coordinated with the image capture device to ensure that the medical targets are at least partially illuminated during the capturing of the images by selecting the drive circuit to output a substantially triangle wave current with a minimum current value greater than zero. In another example, the PWM current is selected such that the images of the medical targets captured by the image capture device are free of defects or artifacts notwithstanding the variable brightness of the at least one LED. In another example, the variable brightness of the at least one LED is selected to provide sufficient illumination for the image capture device to autofocus the medical targets. In another example, the image capture device captures the images by serially generating each of the images from top to bottom or from left to right. 
     Additional variations and modifications of the inventive concepts which are described herein will be readily apparent based on the above description and further in accordance with the following claims.