Abstract:
A portable vein viewer apparatus may be battery powered and hand-held to reveal patient vasculature information to aid in venipuncture processes. The apparatus comprises a first laser diode emitting infrared light, and a second laser diode emitting only visible wavelengths, wherein vasculature absorbs a portion of the infrared light causing reflection of a contrasted infrared image. A pair of silicon PIN photodiodes, responsive to the contrasted infrared image, causes transmission of a corresponding signal. The signal is processed through circuitry to amplify, sum, and filter the outputted signals, and with the use of an image processing algorithm, the contrasted image is projected onto the patient&#39;s skin surface using the second laser diode. Revealed information may comprise vein location, depth, diameter, and degree of certainty of vein locations. Projection of vein images may be a positive or a negative image. Venipuncture needles may be coated to provide visibility in projected images.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/718,422, filed on May 21, 2015, which is a continuation of U.S. application Ser. No. 13/778,426, filed on Feb. 27, 2013, now issued as U.S. Pat. No. 9,061,109, which is a continuation of U.S. application Ser. No. 12/804,506, filed on Jul. 22, 2010, now issued as U.S. Pat. No. 8,463,364, which claims priority on U.S. Provisional Application Ser. No. 61/271,587, filed on Jul. 22, 2009, the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Drawing blood and administering intravenous medication using medical devices including but not limited to catheters are common medical procedures, but conventional methods to perform these procedures have several limitations. First a vein must be found. Conventional methods of locating an appropriate vein or artery include restricting the blood supply to the location of the body so that the blood pressure in that area is greater, which results in the patient&#39;s veins becoming more visible. This is often accomplished by the use of a temporary tourniquet, which can result in extreme discomfort to the patient. Even after the temporary tourniquet is applied and certain veins are exposed, a medical professional may still not be able to find an appropriate vein. This problem can occur more readily in elderly patients and patients with low blood pressure. Thus, there is a need for a non-invasive method for locating veins. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention is directed towards a portable hand-held medical apparatus that uses infrared light to detect veins beneath the skin, then illuminating the position of the veins on the skin surface directly above the veins using visible light. When the apparatus is held a distance above the outer surface of the skin, veins appear vastly different than the surrounding tissue, and veins that are otherwise undetectable because of their depth in the tissue are safely located and mapped on the patient&#39;s skin. Vein&#39;s will be accessed more readily and with greater confidence and as such, venipuctures will go more smoothly while vasculature shows up clearly on the skin&#39;s surface, making it easy to select the best vein to collect a blood sample from or administer medications to. Qualified medical personnel can observe the displayed vasculature to assist them in finding a vein of the right size and position for venipuncture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a perspective view of the apparatus of the present invention. 
           [0005]      FIG. 2  is a perspective view of a charging cradle for the apparatus of  FIG. 1 . 
           [0006]      FIG. 3  is a front view of the apparatus of  FIG. 1 , while being charged in the cradle of  FIG. 2 . 
           [0007]      FIG. 4  is a perspective view of the apparatus of  FIG. 1  being charged in the cradle of  FIG. 2 . 
           [0008]      FIG. 5  is a side perspective view of the apparatus of  FIG. 1 , highlighting the buttons and LCD screen of the device of  FIG. 1 . 
           [0009]      FIG. 6  is a bottom view of the apparatus of  FIG. 1 . 
           [0010]      FIG. 7  is an image of a health care professional utilizing the apparatus of  FIG. 1  to enhance the vein image of veins in a patient&#39;s arm. 
           [0011]      FIG. 8  is a Figure illustrating proper angling of the apparatus when being used to enhance the vein image of veins in a patient&#39;s arm. 
           [0012]      FIG. 9  is a Figure illustrating proper centering of the apparatus when being used to enhance the vein image of veins in a patient&#39;s arm. 
           [0013]      FIG. 10  is a perspective view of the apparatus of  FIG. 1 , with the battery cover removed to show the battery compartment. 
           [0014]      FIG. 11  is a perspective view of the apparatus showing removal of the battery cover. 
           [0015]      FIG. 12  is a perspective view of the apparatus with the battery cover removed, exposing the battery when properly installed in the battery compartment. 
           [0016]      FIG. 13  is a perspective view of battery of the apparatus. 
           [0017]      FIG. 14  is a series of images identifying different indications the LCD display will provide for different battery power levels. 
           [0018]      FIG. 14A  illustrates a Low Battery message displayed on the LCD of the device. 
           [0019]      FIG. 15  is a screen shot of the LCD start screen. 
           [0020]      FIG. 15A  is a screen shot of the LCD when utilized for making configuration setting changes. 
           [0021]      FIG. 15B  shows all of the LCD button icons and their functionality. 
           [0022]      FIG. 16  is a series of screen shots of the LCD display used for modifying the default Vein Display Setting. 
           [0023]      FIG. 17  is a series of screen shots of the LCD display illustrating changing of the Display Time-out interval. 
           [0024]      FIG. 18  is a screen shot illustrating how to change the Backlight Intensity of the apparatus. 
           [0025]      FIG. 19  is a screen shot of the LCD screen used for changing the speaker volume of the apparatus. 
           [0026]      FIG. 20  is a series of screen shots showing the steps for labeling of the apparatus according to a user&#39;s preference. 
           [0027]      FIG. 20A  is a series of screen shots showing use of up/down arrows for character selection. 
           [0028]      FIG. 21  is a screen shot illustrating how to change or review the language utilized on the apparatus. 
           [0029]      FIG. 22  is a screen shot illustrating how to reset all of the settings for the apparatus back to the factory default settings. 
           [0030]      FIG. 23  is a perspective view illustrating plugging a USB cable into the back of the apparatus to communicate with a PC, and a screen shot illustrating the LCD screen of the device schematically illustrating the connection. 
           [0031]      FIG. 24  is a screen shot as it would appear on the PC of  FIG. 23  when looking for the apparatus. 
           [0032]      FIG. 25  is a screen shot as it would appear on the PC after the apparatus was detected, and the software running on the PC was checking to see if the apparatus software was current or needed to be updated. 
           [0033]      FIG. 26  is a screen shot as it would appear on the PC, when an apparatus is not detected by the PC. 
           [0034]      FIG. 27  is a screen shot illustrating the capability of naming the apparatus or changing the language, and doing so from the PC. 
           [0035]      FIG. 28  is a series of screen shots of the PC illustrating the steps in which the software of an apparatus is updated. 
           [0036]      FIG. 29  illustrates a cradle pack and mounting hardware for use in a medical environment utilizing a series of vein enhancing apparatuses. 
           [0037]      FIG. 30  is an exploded view of the apparatus of the present invention. 
           [0038]      FIG. 31  shows a bottom perspective view of the bottom section of the housing. 
           [0039]      FIG. 32  shows a top perspective view of the bottom section of the housing. 
           [0040]      FIG. 33  is a top view of the bottom section of the housing. 
           [0041]      FIG. 34  is a cross-sectional view of the bottom section of the housing. 
           [0042]      FIG. 35  is a bottom view of the bottom section of the housing. 
           [0043]      FIG. 36  is an end view of the bottom section of the housing. 
           [0044]      FIG. 37  is a top view of the top section of the housing. 
           [0045]      FIG. 38  is a side view of the top section of the housing. 
           [0046]      FIG. 39  is a bottom view of the top section of the housing. 
           [0047]      FIG. 39A  is a cross sectional view through the apparatus of  FIG. 39 . 
           [0048]      FIG. 40  is a first section cut through the top section of the housing. 
           [0049]      FIG. 41  is a second cross-section through the bottom section of the housing. 
           [0050]      FIG. 42  is an exploded view of the photodiode assembly. 
           [0051]      FIG. 42A  is a reverse perspective view of the photodiode board in the exploded view of  FIG. 42 . 
           [0052]      FIG. 43  is a top view of the photodiode assembly. 
           [0053]      FIG. 44  is an bottom view of the photodiode engine. 
           [0054]      FIG. 45  shows a perspective view of the bottom section of the housing with a portion of the photodiode assembly mounted inside the cavity of the bottom section of the housing. 
           [0055]      FIG. 46  is a bottom view of the portable apparatus of the present invention. 
           [0056]      FIG. 47  is a view of the inside of the battery cover. 
           [0057]      FIG. 47A  is a view of the outside of the battery cover. 
           [0058]      FIGS. 48A-D  is a assembly level block/schematic diagram of the present invention 
           [0059]      FIGS. 49A-C  is an additional assembly level block diagram of the present invention. 
           [0060]      FIGS. 50A-D  is a schematic of a circuit diagram of the user interface board. 
           [0061]      FIGS. 51A-B  is a schematic of a circuit diagram of the photodiode board connection. 
           [0062]      FIG. 52  is a schematic of a circuit diagram of the USB chip. 
           [0063]      FIGS. 53A-E  is a schematic of a circuit diagram of the photodiode board. 
           [0064]      FIG. 54  is a schematic of a circuit diagram of the battery connector board. 
           [0065]      FIGS. 55A-E  is a schematic of a circuit diagram of the visible laser drive. 
           [0066]      FIGS. 56A-D  is a schematic of a circuit diagram of the laser safety feature of the present invention 
           [0067]      FIGS. 57A-D  is an additional schematic of a circuit diagram of the photodiode engine. 
           [0068]      FIGS. 58A-E  is a schematic of a circuit diagram of the speaker of the present invention. 
           [0069]      FIGS. 59A-G  is an additional schematic of a circuit diagram of the photodiode engine. 
           [0070]      FIGS. 60A-F  is an additional schematic of a circuit diagram of the photodiode assembly. 
           [0071]      FIGS. 61A-E  is a schematic of a circuit diagram of a microcontroller of the present invention. 
           [0072]      FIGS. 62A-D  is a schematic of a circuit diagram of the power supply of the present invention. 
           [0073]      FIGS. 63A-B  is an additional schematic of a circuit diagram of the power supply and its peripheral connections. 
           [0074]      FIGS. 64A-E  is a schematic of a circuit diagram of the battery management system. 
           [0075]      FIGS. 65A-D  a schematic of a circuit diagram of the photodiode engine. 
           [0076]      FIGS. 66A-E  illustrates the graphical or symbolic information that may be projected onto a patient other than just vein imaging. 
           [0077]      FIG. 67A  illustrates a first arrangement of optical detectors that may be used for the apparatus. 
           [0078]      FIG. 67B  schematically illustrates an alternative arrangement of optical detectors. 
           [0079]      FIG. 67C  illustrates a second alternative arrangement for the optical detectors. 
           [0080]      FIG. 68  illustrates one mechanical arrangement for the scanning mirrors. 
           [0081]      FIG. 69  illustrates smoothing of the edges of the scanning mirrors to improve the high resolution images at smooth video rates. 
           [0082]      FIG. 70  illustrates the apparatus illuminating on the skin of a patient, a coated needle that has been inserted beneath the patient&#39;s skin. 
           [0083]      FIG. 71A  illustrates a typical return signal collected from photodiodes of the current invention, with local peaks corresponding to vein locations. 
           [0084]      FIG. 71B  represents the same signal of  FIG. 71A  after differentiation. 
           [0085]      FIG. 72  illustrates a few consecutive scan lines crossing a single vein. 
           [0086]      FIG. 73  is a graph showing the output power versus the forward current for a laser, to illustrate an inflection point. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0087]    The present invention is directed to an apparatus  10  ( FIG. 1 ) that is an opto-electronic device that assists medical practitioners by locating veins and then projecting an image of those veins directly on a patient&#39;s skin. The apparatus may be portable, hand held, and battery powered. However in an alternative embodiment an external power supply may be used to power the apparatus. The apparatus operates by using infrared light to detect veins beneath the skin, and then illuminates the position of the veins on the skin surface directly above the veins using visible light. The apparatus  10  may be battery powered, and rechargeable using a cradle  5  ( FIG. 2 ), and may generally be stored therein ( FIGS. 3-4 ). 
         [0088]    The apparatus  10  generally comprises a housing  11 , internal circuitry  12 , keypad  13 , display  14 , scanner assembly  15 , and battery pack  16 . The housing  11  may generally comprise a top section  17  and bottom section  18  as shown in  FIG. 30 . Although a specific shape for the housing and the top and bottom sections are shown it will be appreciated that this is merely a representative example and other configurations are intended to be included in the invention. The function of the housing  11  is to for example provide a location to mount the internal circuitry  12 , keypad  13 , display  14 , scanner assembly  15 , and battery  16 . A general embodiment of the housing will be disclosed, but it will be generally understood that modifications to the housing to accommodate different internal circuitry, keypad, display, laser assembly, and battery are within the scope of this invention. In addition, if other features are desired the housing may be modified to include those features. 
         [0089]    The housing  11  may be comprised generally of a top section  17  and a bottom section  18 .  FIGS. 31 and 32  show a representation of one embodiment of the bottom housing section  18  of the housing  11 , in perspective views, and which are detailed in  FIGS. 33-36 . As seen in  FIGS. 31 and 32 , the bottom housing section  18  generally comprises a left sidewall  19  and a right those walls  20 , which are connected by a front wall  22  and rear wall  23 . The exterior surfaces of those walls, which may be handled by the user, are seen in  FIG. 35 , while the interior surfaces of those walls, which may receive the electronic circuitry and other components, are visible in  FIG. 33 . 
         [0090]    The walls  19 - 22  may each be angled, and may be so angled simply for aesthetic reasons, or for better handling by a user, or the angling (draft) may be the result of the manufacturing process used to create the housing bottom section  18 , possibly being a casting process, a forging process, or a plastic injection molding process. However, the walls  19 - 22  need not be so angled, and the housing bottom section  18  may also be manufactured using any other suitable manufacturing process or processes, including, but not limited to, machining of the part. One end of the angled walls  19 - 22  may terminate in a generally flat bottom wall  23 , to create an internal cavity  24 . The generally flat bottom wall  23  may transition, using transition wall  25 , into another generally flat wall  23 A. Wall  23 A may be interrupted by a series of internal walls ( 26 A,  26 B,  26 C, and  26 D) extending therefrom and an internal top wall  26 E connecting those internal side walls, to form a compartment that may house the battery  16 . The other end of the angled walls  19 - 22  may terminate in an edge  27 . Edge  27 , at front wall  21  and in the nearby regions of sidewalls  19  and  20 , may be generally planar, but may transition into edge  27 A, which serves as a transition to generally planar edge  27 B that begins at rear wall  22 . Each of the edges  27 ,  27 A, and  27 B of the housing bottom section  18  may have a step for receiving a corresponding protruding flange of the housing top section  17 , when they are joined during assembly of the apparatus  10 . 
         [0091]    In one embodiment, the front wall  21  and sidewalls  19  and  20  of the housing bottom section  18  may have extending up towards the plane of the edge  27 , one or more cylindrical members—a boss  107 , which is adapted to receive mounting screws  106 , and may include the use of threaded inserts for mounting of the housing top section  17  to the housing bottom section  18 . It will be appreciated that other mounting means may be used, including, but not limited to, the use of a snap closure, or a post and recess combination with a friction fit therebetween. 
         [0092]    The bottom wall  23  of housing bottom section  18  may be provided with two orifices  28 , and  29 . On the outside surface of bottom wall  23  there may be one or more annular recesses  28 A and  29 A, being concentric to orifices  28  and  29 , respectfully, each of which may be used to receive a lens  90  ( FIGS. 6 and 10 ). 
         [0093]    Protruding inward from the inside of bottom wall  23  may be cylindrical protrusions  31 , and  32 . Protrusions  31  and  32  may be concentric with orifices  28  and  29 , respectfully, and may be adapted to receive a portion of the photodiode masks  66  and  67  of the scanner assembly  15 , which are discussed later. 
         [0094]    Mounted inside the battery compartment formed by walls  26 A- 26 E may be the battery pack  16 . The battery pack  16  ( FIG. 13 ) can be any of a variety of models known in the art, but in a preferred embodiment, it may be rectangular to fit inside the compartment formed by walls  26 A- 26 E. One end  16 A of the battery pack  16  may be adapted to be received by the power connection  95  on the main circuit board ( FIG. 30 ). The battery pack  16  may be secured in the battery compartment by a battery cover  96  which attaches to the bottom section  18  of housing  11 . The battery cover  96  may attach to the bottom section of the housing  18  in a variety of ways, such as by clips or screws. As seen in  FIG. 47 , the battery cover  96  may be secured by having a pair of flanges  96 A extending therefrom be received in a pair of slots  34  in the bottom section  18  of housing  11 .  FIGS. 62-64  are schematics of circuit diagrams which demonstrate how the battery pack is connected to the internal circuitry  12 , the scanner assembly  15 , and remaining electrical components of the invention. 
         [0095]      FIGS. 37-41  show a representation of one embodiment of the top section  17  of the housing  11 . The housing top section  17  may be formed similar to the housing bottom section  18 , and thus may have a top wall  81  from which extends, generally at an angle, a left sidewall  83  and right sidewall  84 , and a front wall  85  and rear wall  86 . The front wall  85  and rear wall  86  may extend from the left sidewall  83  and right sidewall  84 , respectively, creating an internal cavity  87 .  FIG. 37  shows the outer surfaces of those walls, while  FIG. 39  shows the inner surfaces of those walls. The walls  83 - 86  extend out to a generally planar edge  82 , which may have a peripheral flange protruding therefrom to mate with the recess of the housing bottom section  18 . In one embodiment, housing top section  17  may have extending down from top wall  81  and walls  83 - 86 , towards the plane of the edge  82 , one or more cylindrical members  108 , which are adapted to receive mounting screws  106 , and may include use of threaded inserts. The cylindrical members  108  of the housing top section  17  may be positioned to be in line with the corresponding members  107  of the housing bottom section  18  to be secured thereto during assembly of the scanner  10 . 
         [0096]    The outer surface of the top wall  81  of the housing top section  17  may have a step down into a flat recessed region  81 A having an edge periphery  81 P. That flat recessed region  81 A may comprise of an opening  91  through to the inside surface, which may be a rectangular opening, and a plurality of shaped orifices  93 A,  93 B, and  93 C. The rectangular-shaped opening  91  may be sized and otherwise adapted to receive the display  14 , which is discussed in more detail hereinafter. The flat recessed region  81 A of top wall  81  may receive a display guard  92  ( FIG. 30 ), to provide a barrier between the display  14  and the outside environment. The plurality of shaped orifices  93 , which may also be correspondingly found in the display guard  92 , are adapted to receive a plurality of buttons  77  or other activating means which may be mounted directly under the top plate  81  of the housing top section  17 . In a preferred embodiment, there are three buttons—a first display button  110 , a second display button  111 , and a power button  112 . Buttons  110 - 112  may be any shape practicable, but in a preferred embodiment, display buttons  110  and  111  are elliptical, and button  112  is circular. (Note that a fourth button  113  protruding from the side of the housing, as seen in  FIGS. 5 and 30 , may also be used to power the apparatus up or down, as well as accomplish other functions as well). 
         [0097]    Alternatively, other means of user input, such as touch screen, touch pad, track ball, joystick or voice commands may replace or augment the buttons. 
         [0098]    The internal circuitry  12  is illustrated in  FIGS. 48-65 , and can include a main circuit board  43 , a user interface board  44 , USB chip  46 , and speaker  47 . In one embodiment, the main circuit board  43  contains at least two orifices  48  and  49  which are adapted to receive mounting member  50  and mounting member  51 . Mounting members  50  and  51  may be used to secure the main circuit board  43  to the heat sink  52 . Mounting members  50  and  51  may be screws, or pins or any similar type of member used to secure internal circuitry known in the art.  FIG. 48  is a schematic of a circuit diagram of the main circuit board  43  and how it connects to the remaining components of the present invention. 
         [0099]    As seen in  FIG. 30 , heat sink  52  generally comprises a left sidewall  99 , and right sidewall  100 , and a front sidewall  104  extending between the left and right sidewall. In a preferred embodiment heat sink  52  may also contain a middle bridge  101  which connects the left sidewall  99  with the right sidewall  100 . Extending from the middle bridge and curving downwards is a hook member  102 . The hook member has an internal cavity  103 , which is adapted to receive the USB chip  46 . On the front sidewall  104 , and left and right sidewalls  99  and  100 , there may be cylindrical members  105  that are adapted to receive mounting screws  106 , and may include the use of threaded inserts. Mounting members  40  may be used to mount the scanner assembly  15 . In one embodiment, mounting members  40  may be screws. It will be appreciated that the photodiode assembly may be mounted by other means. 
         [0100]    The heat sink capabilities might be enhanced by a fan or blower arranged in a way that would direct the air flow onto the heat sink and out of the housing. Additionally, a thermodynamic or thermoelectric heat pump may be employed between the heat-dissipating portions of the heat sink, to facilitate heat exchange. In a preferred embodiment, a heat shield  80  is mounted onto the top surface of the user interface board  44 . 
         [0101]    Preferably being directly connected the main circuit board  43 , is the user interface board  44 .  FIG. 50  is a schematic of a circuit diagram of the user interface board. The user interface board  44  contains the firmware which sends a graphic user interface to the display  14 , and stores the user&#39;s preferences. In one embodiment the interface board  44  is directly mounted to the top surface of the main circuit board. In one embodiment, the display  14  is directly mounted to the user interface board  44 , and may be a Liquid Crystal Display (LCD). It will be appreciated to those skilled in the an that an Organic Light Emitting Diode display (OLED) could work equally well. Alternatively, other means of information delivery may be used, such as lamp or LED indicators and audible cues. Some of the information that may be delivered to the user, other than the projection of vein images onto a patient&#39;s arm, may be visual cues also being projected on the patient&#39;s arm alongside the vein images, visual cues regarding additional information concerning the veins. 
         [0102]    Mounted to the user interface board may be a keypad  13 . Keypad  13 , as noted previously, may be comprised of a plurality of control means which may include, but is not limited to, a plurality of buttons  77 . In a preferred embodiment, there may be three buttons used for controlling the apparatus—buttons  110 - 112 . Each of these buttons may have a first end  78  and a second end  79 . The first ends  78  of the plurality of buttons is adapted to be exposed through corresponding openings in the housing top section  17 , where they may be toggled by the user. The second end  79  of the buttons is adapted to be received by the user interface board  44 . 
         [0103]    Also attached to the main circuit board is the USB chip  46 . USB chip mounts to the main circuit board  43  at a pin connection, and provides a pin connection for speaker  65 . The USB chip  46  is preferably mounted to the bottom surface of the main circuit board. 
         [0104]    Also connected to the main circuit board is the scanner assembly  15  ( FIG. 42 ). The scanner assembly  15  generally includes a photodiode engine  53 , a photodiode board  54 , and a heat pipe  55 . In one embodiment, the photodiode engine  53  is directly mounted to the top surface of the photodiode board  54 , by one or more screws  56 ,  57 , and  58 . In another embodiment, the bottom surface of the photodiode board is mounted to a foam fresen  59 . In the same embodiment, the foam fresen  59  is mounted to the bottom plate of the bottom section. In a preferred embodiment the foam fresen  59  has an orifice  69  which is adapted to receive the portion of the photodiode engine which houses the display light  62 . In a preferred embodiment the foam fresen  59  has a first arcuate cutout  75  at its front end and a second arcuate cutout  76  at its rear end. Arcuate cutouts  75  and  76  provide an arcuate surface for grommets  73  and  74  to be received. 
         [0105]    The photodiode engine comprises a display light  62  ( FIG. 44 ).  FIGS. 53, 61, and 65  are schematics of circuit diagrams relating to the photodiode engine and its peripheral connections. The display light  62  may be comprised of at least a red laser  63  and an infrared (IR) laser  64 . In a preferred embodiment red laser  63  may be a laser diode emitting light at a wavelength of 642 nm, and an infrared (IR) laser  64  that may emit light at a wavelength in the near infrared to be at 785 nm. Other combinations of wavelengths of more than two lasers may be used to enhance both the collection of the vein pattern and the display of the collected information. Red laser  63  projects an image of the vein pattern on the patient&#39;s skin. The laser diode has a wavelength of 642 nm, which is in the visible red region, but falls outside the spectral response range of photodiodes  60  and  61 . Red laser  63  illuminates areas with no veins, and does not illuminates areas with veins. This results in a negative image that shows the physical vein locations. Alternatively, the positive image may be used, where the red laser illuminates the vein locations and does not illuminate spaces between veins. 
         [0106]    The red laser may be employed to project information other then vein locations, by means of turning on the laser or increasing its brightness when the laser beam is passing over the brighter parts of graphical or symbolic information to be projected, and turning off the laser or increasing its brightness when the laser beam is passing over the darker parts of graphical or symbolic information to be projected. Such information may include the vein depth, vein diameter, or the degree of certainty with which the device is able to identify the vein location, expressed, for example, through the projected line width  501  ( FIG. 66( a ) ), the length of the strokes in a dotted line  502  ( FIG. 66( b ) ), as a bar graph  503  ( FIG. 66( c ) ) or a numeric indication  504  ( FIG. 66( d ) ). It may also include user&#39;s cues  505  and  506 , respectively for optimizing the position of the device, such as choosing the correct tilt and distance to the target ( FIG. 66( e ) ). 
         [0107]    Vein location and other information may also be displayed by projection means other than scanning laser, through the use of, for example, a DLP (Digital Light Processing) projector, a LCoS (Liquid Crystal on Silicon) micro-projector, or a holographic projector. 
         [0108]    Additionally, the firmware of the photodiode board  54  may be programmed to recognize and modify display  14 , and projection by the display light  62  to represent a needle, catheter, or similar medical device  573  which has been inserted beneath a patient&#39;s skin and a part of it  573   a  is no longer visible to the naked eye ( FIG. 70 ). The needle or medical apparatus may be made with, or coated with a material that absorbs or reflects a specified amount of the light from the IR laser  64 . Glucose is one example of a biomedical material which could be used as a coating to absorb or reflects a specified amount of an IR laser. Photodiodes  60  and  61  will detect the difference in reflection and absorption, and the photodiode board  54  may modify display  14  to show the needle or medical device. The photodiode board  54  may also be programmed to modify projection by the display light  64  so that the needle or medical device which has been inserted into the patient&#39;s skin is displayed. 
         [0109]    More detailed information on the use of the laser light to view the veins can be found in U.S. patent application Ser. No. 11/478,322 filed Jun. 29, 2006 entitled MicroVein Enhancer, and U.S. application Ser. No. 11/823,862 filed Jun. 28, 2007 entitled Three Dimensional Imagining of Veins, and U.S. application Ser. No. 11/807,359 filed May 25, 2007 entitled Laser Vein Contrast Enhancer, and U.S. application Ser. No. 12/215,713 filed Jun. 27, 2003 entitled Automatic Alignment of a Contrast Enhancement System the disclosures of which are incorporated herein by reference. 
         [0110]    The photodiode board  54  comprises one or more silicon PIN photodiodes, which are used as optical detectors in a preferred embodiment, photodiode board  54  comprises at least two silicon PIN photodiodes  60  and  61  ( FIG. 42A ). The field of view (FOV) of the optical detectors is preferably arranged to cover the entire area reachable by light from IR laser  64 .  FIGS. 8 and 10  are schematics of circuit diagrams which represent the photodiode board and its peripheral connections. In front of these photodiodes  60  and  61  are filters  120  and  121  ( FIG. 42A ) to serve as an optical filters that transmit infrared light, but absorb or reflect light in the visible spectrum. Mounted to photodiode  60  and  61  may be photodiode masks  66  and  67 . Photodiode masks  66  and  67  comprise a shaped orifice  68  which is adapted to be received by photodiode  60  and  61  respectively. In a preferred embodiment photodiode masks  66  and  67  are circular and are adapted to be received by the cylindrical protrusions  31  and  32  of the housing bottom section  18 . The photodiode board  54  is further comprised of an orifice  70 . The opening  70  may be rectangular and adapted to receive the portion of the photodiode engine which houses display light  62 . In a preferred embodiment the photodiode board  54  has a first arcuate cutout  71  at its front end, and a second arcuate cutout  72  at its rear end. Arcuate cutouts  71  and  72  provide an arcuate surface for grommets  73  to be received. 
         [0111]    Other arrangements of optical detectors may be used too. In one possible arrangement, depicted on  FIG. 67( a ) , the photodiode&#39;s field of view (FOV)  510  may be shaped by lenses-Fresnel lenses, curved mirrors or other optical elements  511 —in such way that the FOV extent on the patient&#39;s arm becomes small and generally comparable with the size of the IR laser spot  512 . This reduced FOV is forced to move synchronously with the laser spot by virtue of directing the optical path from the patient&#39;s arm to the photodiodes through the same scanning system  513  employed for the scanning of the laser beam, or through another scanning system, synchronous with the one employed for the scanning of the laser beam, so the FOV continuously overlaps the laser beam and follows its motion. Additional optical elements, such as a bounce mirror  514 , might be used to align the laser bean with FOV. Such an arrangement is advantageous in that it enables the photodiodes to continuously collect the reflected light from the IR laser spot while the ambient light reflected from the rest of the target generally does not reach the photodiodes. 
         [0112]    Alternatively, the FOV of the photodiodes may be reduced in only one direction, and routed through the scanning system in such way that it follows the laser beam only in the direction where the FOV has been reduced, while in the other direction the FOV covers the entire extent of the laser scan ( FIG. 67( b ) ). Such FOV may be shaped, for example, by a cylindrical lens in front of a photodiode. As the laser spot  512  is moving along a wavy path defined by superposition of the fast horizontal scan and slow vertical scan, the FOV moves only vertically, which the same speed as the slow vertical scan, thus covering the scan line the laser spot is currently on. Such arrangement may be implemented, for example, by routing the FOV of the photodiode only through the slow stage of the scanning system  513 , but not its fast stage. Yet alternatively, the FOV may be shaped to follow the laser beam in close proximity without overlapping it ( FIG. 67( c ) ). In this case, the FOV still moves in sync with the laser spot  512 , but since it does not include the laser spot itself, the light reflected from the surface of the skin does not reach the photodiode. Instead, some portion of the light which penetrates the body, and, after scattering inside tissues, re-emerges from the skin surface some distance away from the laser spot, forming an afterglow area  515 , which is partly overlapped with FOV. Collecting only the scattered light while reducing overall signal strength, has the advantage of avoiding variations caused by non-uniform reflections from random skin features and may be helpful in discerning deep veins. 
         [0113]    Multiple photodiodes may also be arranged in an array in such way that their individual FOVs cover the entire area illuminated by the IR laser. At any given moment, only the signals from one or more photodiodes whose FOV overlap the laser beam or fall in proximity to it may be taken into the account. 
         [0114]    The photodiodes convert the contrasted infrared image returning from the patient into an electrical signal. The photodiode board  54  amplifies, sums, and filters the current it receives to minimize noise. The return signal of the photodiode engine  53  is differentiated to better facilitate discrimination of the contrast edges in the received signal received by photodiodes  60  and  61 .  FIG. 71 ( a )  represents a typical signal collected from photodiodes  60  and  61  and digitized. Local peaks  580  correspond to the locations of veins in the patient body.  FIG. 71 ( b )  represents the same signal after the differentiation. Since differentiation is known to remove the constant parts of the sip al and amplify its changing parts, peaks  580   a  can be easily found by comparison to ground reference (zero signal level of  FIG. 71( b ) ). The photodiode board  54  also determines the locations where the infrared light has the lowest signal reflectivity using a scan system. These lower reflectivity locations indicate the vein locations. 
         [0115]    Signal processing methods other than differentiation, including Digital Signal Processing (DSP) may be employed as well, such as Fast Fourier Transform (FFT), Finite Impulse Response (FIR) and Infinite Impulse Response (IIR) filtration. Additionally, more complex image processing algorithms might be used, for example based on continuity analysis, as the veins generally form continuous patterns. For example,  FIG. 72  shows a few consecutive scan lines crossing a single vein  592 . While most lines produce distinctive signal peaks  590 , indicating the vein location, in some lines those picks might by masked by noise  591 . Still, connecting the vein location points derived from distinctive picks allows the algorithm to establish and display the true location of the vein. 
         [0116]    To facilitate the use of DSP algorithms, the electronic circuitry to digitize the signal from the photodiodes and store it subsequently in some form of digital memory might be provided. Consequently, the display of the vein pattern by the red laser might be delayed with respect to the acquisition of said pattern with the IR laser. Such delay may vary from a small fraction of the time interval needed to scan the entire display area to several such intervals. If necessary, an intentional misalignment between the red and IR laser might be introduced, so the red laser can light up or leave dark the areas where the IR laser detected the lower or higher reflectivity, although the red laser beam would travel through those areas at different times than the IR laser. 
         [0117]    The scan system employed by the apparatus  10  of the present invention uses a two dimensional optical scanning system to scan both the infrared and visible laser diodes. A dichroic optical filter element  125  in  FIG. 44  allows laser diodes  63  and  64  to be aligned on the same optical axis and be scanned simultaneously. This allows for a minimal time delay in detecting the infrared reflected signal, and then re-projecting the visible signal. 
         [0118]    The scan system employed by the apparatus  10  of the present invention has a horizontal and vertical cycle. Vertical scanning is driven in a sinusoidal fashion, and in one embodiment it occurs at 56.6 Hz, which is derived from 29 KHz sinusoidal horizontal scan. The Scan system is also interlaced. During a horizontal cycle the projection system is active only one half the horizontal scan system and blanked during the alternate half of the scan cycle. On the alternate vertical cycle the blanked and active portion of the horizontal scan is reversed. The top and bottom areas of the scan are blanked as well with a small area at the top of scan, located behind a mechanical shield for safety, reserved for execution of a laser calibration activity. 
         [0119]    Alternative scan system might be used as well, such as those using a single scanning mirror deflectable in two orthogonal directions, or two uni-directional mirrors with smaller ratios of horizontal and vertical frequencies, such that the scan pattern forms a Lissajou figure (See http://www.diracdelta.co.uk.science/source/l/i/lissajous%20figures/source.html, and for animated figures, http://ibiblio.org/e-notes/Lis/Lissa.htm, which are incorporated herein by reference). 
         [0120]    Various mechanical arrangements for scanning mirrors may be used. In one embodiment ( FIG. 63 ) the mirror  550 , made of glass, plastic or silicon, is attached to a free end of a cantilevered torsion fiber  551 , made of glass or other linearly-deformable material, the other end of which is fixed to a base plate  552 . A magnet  553 , polarized in a direction perpendicular to the fiber, is attached to the fiber between the base plate and the mirror. A coil  554  may be positioned in close proximity to the magnet. The coil  554  may be used both for driving the mirror by virtue of energizing it with AC current, as well as for collecting the positional feedback by virtue of amplifying the voltage induced in the coil by magnet&#39;s oscillations. Both functions may be accomplished simultaneously, for example, by using one half of the mirror&#39;s oscillatory cycle for driving and the other half for collecting feedback. Alternatively, other means of driving the mirror, such as inducing torsional oscillation on the entire base plate by means of a piezo-electric element  555 , might be used. The magnet  553  and the coil  554  are used exclusively for feedback in this case. 
         [0121]    The torsion mode of the fiber  551  may be higher than fundamental, meaning that at least one torsional node, i.e. a cross-section of the fiber which remains still during oscillations, is formed. Such nodes allows for generally higher oscillation frequency at the expense of generally lower oscillation amplitude. 
         [0122]    Since high oscillation frequency is desirable to obtain high-resolution images at smooth video rates, the linear speed of the mirror&#39;s outer edges becomes quite high as well, leading to excessive dust buildup along those edges. To alleviate this problem, the edges of the mirror may be smoothed by either removing some mirror material  560  ( FIG. 69 ), or adding a layer of bevel-shaped coating  561  around the edges of the mirror. 
         [0123]    Non-mechanical scanning systems, such as acousto-optic, electro-optic or holographic might be employed as well. 
         [0124]    In a preferred embodiment, each scan line is divided into 1024 pixels numbered  0 - 1023 . In pixel range  0 - 106 , red laser  63  is at its threshold, and IR laser  64  is off. The term “threshold”, as applicable to lasers, means an inflection point on the laser Power-Current (P-I) curve, where the current becomes high enough for the stimulated emission (aka “lasing”) to begin. This point is marked Ith of  FIG. 73 , which, while taken from the documentation of Sanyo Corp., is representative of the vast majority of laser diodes. In pixel range  107 - 146 , red laser  63  is active, and IR laser  64  is at its threshold. In pixel range  182 - 335 , red laser  63  is active, and IR laser  64  is on. In pixel range  886 - 915 , red laser  63  is active, and IR laser  64  is off. In pixel range  916 - 1022 , red laser  63  is at its threshold, and IR laser  64  is off. In pixel range  0 - 106 , red laser  63  is at its threshold, and IR laser  64  is off. 
         [0125]    Projection is accomplished by loading the appropriate compare registers in the complex programmable logic device, or CPLD. The content of the registers is then compared to the running pixel counter, generating a trigger signal when the content of a register matches the pixel count. The “left” register is loaded with the pixel count of when the laser should be turned off and the “right” register loaded with the pixel count of when the laser should be turned back on. The registers should be loaded on the scan line prior to the line when the projection is to occur. Projection is only allowed during the “Active” part of the red laser scan, i.e. between pixels  107  and  916 , as explained above. 
         [0126]    To improve vein visibility it is important to maintain the laser spot of a proper size on the surface of the patient&#39;s skin. This may be accomplished by fixed laser-focusing optics, or by an auto-focusing system which adjusts the beam focusing in response to changes in the distance to the target. 
         [0127]    Certain patient&#39;s veins or a portion of their veins might not be displayed well or at all. Causes for veins not be displayed include vein depth skin conditions (e.g. eczema, tattoos), hair, highly contoured skin surface, and adipose (i.e. fatty) tissue. The apparatus is not intended to be used as the sole method for locating veins, but should be used either prior to palpation to help identify the location of a vein, or afterwards to confirm or refute the perceived location of a vein. When using the apparatus qualified medical personnel should always follow the appropriate protocols and practices. 
         [0128]    In one embodiment, when the user wishes to operate the apparatus, the user may apply a perpendicular force to the top surface of the side button  113 , or depress power button  112  to power the device. Once the device has been powered, the user can turn on the display light  62  by pressing and holding the top surface of the side button  113  for a set amount of time. In a preferred embodiment the photodiode board  54  has been programmed to activate the display light  62  after the user has held side button  113  for a half second. 
         [0129]    Embedded in the user interface board  44  may be firmware, which supports the displaying, upon LCD  14 , of a menu system (see  FIGS. 15-22 ). The menu system permits a user to access a plurality of features that the apparatus of the present invention can perform. The user can cycle through different display modes that the firmware has been programmed to transmit to the display by tapping the top surface of the side button  98 . The features embedded in the firmware can include a menu system, menu settings, display status. In one embodiment, the first LCD button  110  is programmed to access the menu mode ( FIG. 15 ). One of those features of the firmware permits labeling or naming of a particular apparatus, as seen in  FIG. 20 . Such labeling may become advantageous in an environment where a medical service provider utilizes a plurality of the apparatus  10 , such as in an emergency room. The plurality of apparatus  10  may be maintained in a corresponding plurality of rechargeable cradles  5 , which may be mounted to a bracket  200 , and secured thereto using fastening means  201 , as seen in  FIG. 29 . Power to the cradles  5  may be supplied from an adapter  202  plugged into a wall outlet, with a power splitter  203  supplying power to each cradle  5 . Each of the plurality of apparatus  10  in this example may be appropriately labeled, “ER1,” “ER2,” . . . 
         [0130]    When the apparatus&#39;s  10  display light  62  is activated, the apparatus  10  can be used to locate veins. The user can access the scan function by navigating to it using the keypad  13 . The firmware will contain a feature which will allow the user to cycle through display settings using a menu system to optimize vein display for the current subject. When the display light  62  is deactivated, the display  14  remains available for viewing status and making configuration settings using the menu system.