Abstract:
A polarizing hood including a first polarized filter with the center of the filter removed. Placed forward and in front of the first polarized filter is a second linear polarized filter substantially the size of the hole in the first polarized filter and is held in place by a clear lens. The polarization may be adjusted. In response to light collocated with an objective lens shined through the first polarizing filter, the light become polarized. The reflected polarized light returns through the second polarized filter, and full polarization is accomplished with respect to the viewing camera.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 61/537,507, entitled “DUAL POLARIZING HOOD” filed Sep. 21, 2011, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a polarizing lens hood for at least one of digital still or digital video cameras, and more specifically to a dual polarizing lens hood for at least one of digital still or digital video cameras that have a light source collocated with the camera lens objective. 
       BACKGROUND OF THE INVENTION 
       [0003]    In general, light can be described as a transverse electromagnetic wave and thus its interaction with matter can depend on the orientation of the electric field vector. Such phenomena and interaction are called polarization effects. Various optical elements can change the polarization of a light beam. A polarizing filter may be used to select which light beams/rays are viewed by a lens. Linear Polarizing (PL) and Circular Polarizing (PL-CIR) filters may remove unwanted reflections from non-metallic surfaces such as water, glass, etc. In some cases, use of a polarizing filter may also enable colors to become more saturated and appear clearer, with better contrast. 
         [0004]    Historically, a lens of a camera may be fitted with a single polarizer to filter the light from the sun. However, in certain situations it may be advantageous to provide a secondary light source to a lens and/or camera. 
         [0005]    Accordingly, there exists a need for a polarizer and that polarizes its own light source and reflects the polarized light back through another polarizing lens into the receiving lens. There also exists a need for a removable hood when polarization is not desired. There also exists a need for the level of polarization to be adjustably controlled. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present disclosure recites a first polarizer coupled to a light source configured to reflect polarized light back through another polarizing lens into a receiving lens. The present disclosure also discloses detaching a removable polarizing hood when polarization is not desired. The present disclosure also discloses adjustably controlling the polarization level. 
         [0007]    Advantages of the present invention will become more apparent to those skilled in the art from the following description of the embodiments of the disclosure which have been shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects. Accordingly, the drawing(s) and description are to be regarded as illustrative in nature and not as restrictive. Additionally, the measurements disclosed in the drawings are to be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0008]      FIG. 1A  is an isometric top view of an embodiment of a dual polarizing hood; 
           [0009]      FIG. 1B  is an isometric side view of the dual polarizing hood of  FIG. 1A ; 
           [0010]      FIG. 1C  is an exploded side view of the dual polarizing hood of  FIGS. 1A and 1B ; 
           [0011]      FIG. 1C  is an exploded view of the dual polarizing hood of  FIGS. 1A and 1B ; 
           [0012]      FIG. 1D  (section A-A) is an exploded view of the dual polarizing hood of  FIGS. 1A and 1B  along cross section A; 
           [0013]      FIG. 1E  is a side exploded view of the dual polarizing hood of  FIGS. 1A and 1B . 
           [0014]      FIG. 1F  is a bottom view of the dual polarizing hood of  FIGS. 1A and 1B ; 
           [0015]      FIG. 1G  is a side view of the dual polarizing hood of  FIGS. 1A and 1B ; 
           [0016]      FIG. 1H  is a top view of the dual polarizing hood of  FIGS. 1A and 1B ; 
           [0017]      FIG. 2  depicts a side cutaway view of the operation of an dual polarizing hood; 
           [0018]      FIG. 3  is a block diagram illustrating a multisensory device imaging a target and interfacing with a video capture component; 
           [0019]      FIG. 4  is a side view illustrating a handheld video examination camera in accordance with one embodiment of the invention; 
           [0020]      FIG. 5  is an exploded view further illustrating the handheld video examination camera of  FIG. 4 ; 
           [0021]      FIG. 6  is an exploded view further illustrating a portion of the camera of  FIG. 4 ; 
           [0022]      FIG. 7  further illustrates a portion of the handheld video examination camera of  FIG. 4 . 
           [0023]      FIG. 8  is a side exploded view of a light-sensor construction in the camera of  FIG. 5 ; 
           [0024]      FIG. 9  is a perspective view further illustrating the light-sensor construction of  FIG. 8 ; 
           [0025]      FIG. 10  is a side view further illustrating the light-sensor construction of  FIG. 8 ; and 
           [0026]      FIG. 11  is a bottom view further illustrating the light assembly of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The following descriptions are of exemplary embodiments of the invention only, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description is intended to provide convenient illustrations for implementing different embodiments of the invention. As will become apparent, various changes may be made in the function and arrangement of the elements described in these embodiments without departing from the spirit and scope of the invention. For example, various changes may be made in the design and arrangement of the elements described in the preferred embodiments without departing from the scope of the invention as set forth in the appended claims. 
         [0028]    In general, the present invention provides a dual polarizing lens hood for at least one of digital still or digital video camera, and more specifically to a dual polarizing lens hood for a camera that has a light source collocated with the camera lens objective. For example, as described further herein and in accordance with various exemplary embodiments of the present invention, a system for polarizing light provided by a light source via a first polarizer and further polarizing reflected light by a second polarizer, such that the provided light and the reflected light are each directed through the polarizing portion of the first and second polarizers one time. 
         [0029]    Referring to  FIGS. 1A and 1B , an exemplary embodiment of a dual polarizing hood  100  is shown (top view and side view). In various embodiments, the dual polarizing hood  100  may comprise a hood body  110 , a polarizing window  120 , and a rotational window/polarizer  130 . The polarizing hood may also comprise a derm hood  150 , and a switch  160  for adjusting the polarization of the device. 
         [0030]    In an exemplary embodiment, the hood body  110  is configured to provide structural support for the various polarizing hood  100  elements. Though it may be any suitable shape, in an embodiment, the exterior surface of hood body  110  is generally conical. Hood body  110  may be formed from a rigid material. In an embodiment, hood body is opaque. In various embodiments, at least a portion of hood body may be clear. The exterior diameter of hood body  110  is configured to gradually increases from the end of hood body  110  intended to be coupled to a lens  117 , to the opposite end  115  of hood body  110 . Hood body generally comprises an open internal cavity running from one end  117  of the polarizing hood to the other end  115 . Similar to the exterior surface of hood body  110 , and with reference to  FIG. 1D , an exploded view of the polarizing hood of  FIGS. 1A and 1B  along cross section A-A, the interior cavity of hood body  110 , gradually increases from the end  117  to the opposite end  115  of hood body  110 . 
         [0031]    End  117  of hood body  110  may comprise features for coupling polarizing hood  100  to another object. For instance, coupling polarizing hood  100  to a still and/or video digital camera, such as camera  301 . These features for coupling may be threading, clips, grooves for receiving anchoring members, pressure fit, and the like. This coupling is intended to be suitably strong to retain the polarizing hood  100  to another object as desired and to allow for convenient decoupling of polarizing hood  100  from the object as desired, for instance, when polarization is not desired. 
         [0032]    Hood body  110  may comprise surface features to aid in gripping the polarizing hood  100  and/or coupling and decoupling the polarizing hood  100  from a still and/or video digital camera device, such as camera  301 . Hood body  110  may also comprise surface features to aid in retaining optional derm hood  150 . For instance, hood body  110  may comprise a raised lip  112  around at least a portion of end  115  which derm hood  150  may be press fit over. For instance, and with reference to exploded view of polarizing hood  100   FIGS. 1C and 1D , the raised lip  112  can be seen juxtaposed end  115 . Optionally, in various embodiments a clear lens may be coupled to end  115  to prevent debris and other unwanted particles from entering end  115 . 
         [0033]    In an embodiment, though it may be made from any suitable material, derm hood  150  may be made from a polymer, such as a medical grade polymer. Derm hood  150  may be any suitable shape; such as conical, elliptic cylinder, parabolic cylinder, hyperbolic cylinder or cylindrical. In an embodiment, with renewed reference to  FIGS. 1A-1G , derm hood  150  is substantially cylindrical with an open interior. The interior dimension of derm hood  150  may substantially mirror the exterior surface dimensions of the end  115  of hood body  110 . As shown, derm hood  150  may be coupled to hood body  110  by elastically stretching derm hood  150  over raised lip  112 . In some embodiments, derm hood  150  is configured for one time use to promote sanitary and sterile objectives. In this manner, derm hood  150  may be in contact with a surface such as the skin of a patient and replaced with a second derm hood  150  prior to contacting a second surface, such as the skin of a second patient. Derm hood  150  may cover end  115  of hood body  110  or it may cover the majority of the external surface of hood body  110  (not shown). 
         [0034]    Hood body  110  may comprise surface features to aid in positioning polarizing hood  100 . For instance, hood body  110  may be marked with one or more surface markings, such as an arrow or line to indicate  0  axis position, to aim hood body  110  and an associated camera. 
         [0035]    In an embodiment and with reference to  FIG. 1E , hood body  110  may comprise a slot opening  180  for a portion of rotational window/polarizer  130  to pass through (described in greater detail below). 
         [0036]    Hood body  110  may also comprise surface features to aid positioning rotational window/polarizer  130 . For instance, hood body  110  may be marked with one or more surface markings adjacent to and/or near slot opening  180 , such that a user may be able to select and note a preferred polarization setting. For instance, dashes at regular intervals with associated characters, such as numbers, to indicate degrees from the 0 axis position. Polarizing window  120  may comprise a polarizing filter. For instance, the polarizing filter may be a linear polarizing filter, circular polarizing filter, or reflecting polarizing filter. The linear polarizing filter may be dichroic. In its broadest sense the term dichroism may refer to the selective absorption of one of the two orthogonal components of an incident beam of light. The polarizing filter may be impregnated with a compound which makes the molecules conductive so they absorb light whose electric field is parallel to the molecular chains. The resultant polarizing filter blocks waves with electric fields along the molecular axes, and passes waves with perpendicular electric fields. The output is a beam which is linearly polarized along the preferred axis. 
         [0037]    Metering and auto-focus sensors in certain cameras, including virtually all auto-focus single lens reflect cameras, may not work properly with a linear polarizer because the beam splitters used to split off the light for focusing and metering are polarization-dependent. A circular polarizer may include a linear polarizer on the front, which selects one polarization of light while rejecting another, followed by a quarter wave plate, which converts the selected polarization to circularly polarized light inside the camera, which works with most all types of cameras, because mirrors and beam-splitters split circularly polarized light the same way they split unpolarized light. 
         [0038]    Polarizing window  120  may be configured to have a substantially circular cross section sized to securably fit inside the interior of hood body  110 . In an embodiment, polarizing window  120  is positioned with the center of its face perpendicular to the axis running through hood body  110  facing end  117 . The polarizing filter of polarizing window  120  may be oriented in any suitable orientation, such as with the 0 axis of the polarizing filter directed to the top of hood body  110  (e.g., twelve o&#39;clock). Alternatively, polarizing window  120  may be oriented to optimally interact with known/or measured properties of the provided light source. 
         [0039]    The polarizing filter selected may be optimized based on the type of light source. For instance, a polarizing filter for white light (about 560 nm) may not be as efficient as for other light sources such as blue (480 nm), green (560 nm), and/or red (660 nm). The polarizing filter may comprise a multi-resistance coating, to help prevent scratches and repel dirt and water. This coating may also reduce flare and ghosting at the filter surface. The polarizing filter may be a neutral polarization filter with weather and/or dust sealing. 
         [0040]    In an embodiment, polarizing window  120  comprises a polarizing portion and a non-polarizing portion. For instance, polarizing window  120  may comprise an opening  122  towards the center of polarizing window  120  to allow reflected light to reach the lens without passing through the polarizing filter of polarizing window  120 . Opening  122  may be a circular opening. For instance, the polarizing filter of polarizing window  120  may be oriented around at least a portion of the perimeter of polarizing window  120 . In another embodiment, polarizing window  120  may comprise a clear non-polarizing lens  122  towards the center of polarizing window  120  to allow reflected light from end  115  to a provided lens without passing through a polarizing filter of polarizing window  120 . 
         [0041]    In an embodiment, the polarizing filter of polarizing window  120  may be fitted in hood body  110  such that the polarizing filter portion of polarizing window  120  polarizes light emitted from a light source collocated with a lens, such as an embedded light, and does not polarize light reflected from end  115  to the lens. 
         [0042]    Rotational window/polarizer  130  may comprise a polarizing filter. For instance, the polarizing filter may be a linear polarizing filter, circular polarizing filter, or reflecting polarizing filter. Rotational window/polarizer  130  may be configured to have a substantially circular cross section. In an embodiment, rotational window/polarizer  130  is positioned with the center of its face perpendicular to the axis running through hood body  110  facing end  115 . 
         [0043]    In an embodiment, rotational window/polarizer  130  comprises a polarizing portion and a non-polarizing portion. For instance, rotational window/polarizer  130  may comprise a clear lens (e.g., the non-polarizing portion) towards perimeter of rotational window/polarizer  130  to allow light from a light source collocated with a lens, such as an embedded light, to reach end  115  without passing through the polarizing filter of rotational window/polarizer  130 . Rotational window/polarizer  130  may also comprise a small polarizing filter located towards the center of rotational window/polarizer  130  configured to filter reflected light entering end  115 . 
         [0044]    Rotational window/polarizer  130  may comprise an extension arm  135  configured to extend radially through slot opening  180 . Switch  160  may be coupled to a distal portion of extension arm  135  extending through slot opening  180 . Rotational window/polarizer  130  may be manually rotated about the center axis of hood body  110 . Stated another way, in an embodiment, rotational window/polarizer  130  may be rotated with respect to the objective of a lens. This rotation may allow a user to select a preferable level of polarization. Switch  160  may comprise a surface feature such as a tab or marking which when used with the surface markings adjacent to and/or near slot opening  180  on hood body  110  to align rotational window/polarizer  130  in a preferable orientation. The intensity of the reflected light may be adjusted by rotating rotational window/polarizer  130 . Though window and polarizer  130  is depicted as being manually adjusted, it should be appreciated that rotational window/polarizer  130  may be mechanically and/or automatically rotated in response to electrical control signaling from a controller. It should also be appreciated, that in accordance with Brewster&#39;s law, at a certain orientation of rotational window/polarizer  130 , all light may be absorbed by polarizing filter  132 . 
         [0045]    In an embodiment, the polarizing portion of polarizing window  120  substantially overlaps the non-polarizing portion of rotational window/polarizer  130 , and the non-polarizing portion of polarizing window  120  substantially overlaps the polarizing portion of rotational window/polarizer  130  relative to light passing parallel through the center axis of hood body  110 . 
         [0046]    Internal retaining ring  140  may be coupled to hood body  110 . Internal retaining ring  140  may be configured to retain rotational window/polarizer  130  in position. For instance, polarizing window  120  may be permanently or semi-permanently coupled in place within hood body  110  using an epoxy, glue, press fit or other suitable securing mechanism. Similarly, internal retaining ring  140  may be coupled in place within hood body  110  using an epoxy, glue, press fit or other suitable securing mechanism. In an embodiment, rotational window/polarizer  130  may be sandwichably positioned between internal retaining ring  140  and polarizing window  120  such that rotational window/polarizer  130  may be rotated about the central axis of hood body  110  (as allowed by the movement of extension arm  135  in slot  180 ). A lubricant may be added to the edge of rotational window/polarizer  130  to aid in rotation. It should be appreciated that though rotational window/polarizer  130  is depicted as being closest to end  117  with respect to polarizing window  120 , the polarizing hood would operate as intended if polarizing window  120  was located closest to end  117  with respect to rotational window/polarizer  130 . 
         [0047]      FIGS. 1F-1H  are bottom, side and top views (respectively) of the polarizing hood  100 . 
         [0048]      FIG. 1G  is a side view of the dual polarizing hood of  FIGS. 1A and 1B . 
         [0049]      FIG. 1H  is a top view of the dual polarizing hood of  FIGS. 1A and 1B . 
         [0050]    With reference to  FIG. 2 , the polarizing hood  100  is directed towards an object of interest, (in this case, a hand). Light  210  from a light source embedded with a lens, such as on the same plane as a lens or near a lens is configured to be directed into end  117 . The light  210  is directed through the polarizing filter portion of polarizing window  120 . This polarizing/filtering of the provided light source creates controlled beams/rays of light to illuminate a target object. Using polarized light, the details of a specimen and/or object being illuminated, including its color, composition and structure which are normally invisible or difficult to discern using non-polarized light may be apparent. The polarized light is directed through the non-polarizing portion of rotational window/polarizer  130  (e.g., clear lens). The polarized light exits end  115 . The polarized light illuminates the object of interest. Depending on the subject matter desired to be illuminated and the distance the subject is from end  115 , additional grades of polarizer may be implemented in polarizing hood  100 . For instance, various grades of polarizer may be implemented to pass different amounts of polarization. 
         [0051]    The light is configured to be at least partially reflected from the object of interest through end  115  towards end  117 . The reflected light  220  is directed through the polarizing filter portion  132  of rotational window/polarizer  130 . The polarized reflected light  220  is directed through the non-polarizing portion of polarizing window  120  (e.g. opening  122 ). The polarized reflected light passes through end  115 . The polarized reflected light is captured by a provided lens. Optionally, a user may adjust the desired polarization level of the reflected light by rotating rotational window/polarizer  130  a desired amount by manipulating switch  160 . In various embodiments, rotational window/polarizer  130  may be locked in a preferred orientation using switch  160 . In various embodiments, switch  160  has a first position and a second position. While switch  160  is in a first position, rotational window/polarizer may rotate with freedom. In response to switch  160  being in the second position a force is place on the exterior of hood  110  and rotational window/polarizer  130  may be locked in a preferred orientation, until switch put back into the first position. 
         [0052]    Polarizing hood  100  may be suitably combined with aspects of a camera as disclosed in patent application Ser. No. 12/319,049, titled “System and Method for video Medical Examination and real time Transmission to remote Locations” filed Dec. 31, 2008. For instance, with reference to  FIGS. 3 to 11  describe an exemplary embodiment of a video camera  301  that can be utilized in conjunction with Polarizing hood  100 . The camera  301  may be a small, handheld, high-resolution examination camera. This camera may be used in the medical and life science fields. Polarization in spectral topography can vastly improve histopathological studies. Camera  301  is durable, light-weight, easy-to-use, includes a snap-shot capability and is freeze-frame ready. Camera  301  can interface directly into any number of analog or digital video processing devices as needed. 
         [0053]    The block diagram  100  of  FIG. 3  includes an examination video camera  301  having an optical end  305  and an interface end  303  comprising an optical sensor assembly  330  in electrical communication with a camera body  340 . Camera body  340  interfaces  350  a connection  360  which can be wired, optical, or wireless. Connection  360  provides data communication and, optionally, power to and from camera  301 . Optical/sensor assembly  330  includes a light producing assembly  500  ( FIG. 9 ) which provides illumination  210 . Assembly  500  may be axially aligned with a lens assembly and is positioned so as not to illuminate the lens assembly other than via light  220  reflected off target  320  and up through the lens assembly into camera  301 . The lens assembly may include a lens fixedly mounted inside a hollow lens barrel. 
         [0054]    Light  220  reflected from a target  320  is received and processed by optical/sensor assembly  330 , is relayed to the camera body  340 , and is transmitted to a video capture and/or processing component  370 . Optional attachments  310  can be mounted on the optical end of the camera body  140 , and may include for example polarizing hood  100 . 
         [0055]    An external view of camera  301  is shown in  FIG. 4 .  FIG. 5  is a partial exploded view of the handheld video examination camera  301 , an optical/sensor assembly  330 , camera body  340  and housing. In  FIGS. 6 and 7 , the optical sensor assembly  330  is shown in further detail and includes sensor/LED assembly  500 , a head, a lens barrel, and a window. In  FIGS. 8 and 9 , LEDs  550  are mounted on LED board  540  and wires  530  each deliver electricity to an LED  550 . When assembled, LED board  540  is secured adjacent spacer  520 , and spacer  520  is secured adjacent sensor board  510 . Sensor  515  is mounted on board  510 . 
         [0056]    LEDs  550  or another desired light source can produce visible or non-visible light having any desired wavelength, including, for example, visible colors, ultraviolet light, or infrared light. The light source can produce different wavelengths of light and permit each different wavelength to be used standing alone or in combination with one or more other wavelengths of light. The light source can permit the brightness of the light produced to be adjusted. For example, the light source can comprise 395 nM (UV), 860 nM (NIR), and white LEDs and can operated at several brightness levels such that a health care provider can switch from white light to a “woods” lamp environment at the touch of a control button on the camera  301 . The light source, or desired portions thereof, can be turned on and off while camera  301  is utilized to examine a target. In some instances, it may be desirable to depend on the ambient light and to not produce light using a light source mounted in camera  301 . In which case reflected light  220  comprises ambient light and/or light from other than the light source collocated with the lens. 
         [0057]    While preferred embodiments of the present invention have been described, it should be understood that the present invention is not so limited and modifications may be made without departing from the present invention. The scope of the present invention is defined by the appended claims, and all devices, process, and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.