Patent Publication Number: US-6219250-B1

Title: Night vision binoculars

Description:
This is a Divisional of application Ser. No. 08/627,149, filed Apr. 3, 1996, now U.S. Pat. No. 5,847,868. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to optical devices that enable a viewer to observe objects at night or during other low-light conditions. More particularly, the present invention relates to a handheld binocular system that can be manufactured at low cost for sale to the general public. 
     BACKGROUND OF THE INVENTION 
     Night vision devices are widely used in the military to provide soldiers, aviators and sailors with the ability to view objects at night or during other low light conditions. As a result, many night vision devices are currently being manufactured according to exacting military specifications and designs. Similarly, many such night vision devices are being manufactured for specific military applications such as part of the sights of various weapons or as part of goggle assemblies that attach to an aviator&#39;s or soldier&#39;s helmet. As a consequence, many of the night vision devices currently being manufactured are neither affordable nor easily adapted to non-military uses by the general public. 
     Night vision devices typically include an image intensifier tube that converts infrared energy into visible light. Such night vision devices typically require sophisticated power supplies and circuitry to control the operation of the image intensifier tube and sophisticated optical arrangements that direct the infrared energy into the image intensifier tube and visible light away from the image intensifier tube. In military applications, the various military personnel are trained in how to use and adjust the night vision devices they are issued. However, a night vision device designed for use by the general public would have to provide simple adjustments that can be readily operated by a variety of different users in a dark environment. Furthermore, a night vision device designed for use by the general public would also require various adjustable optical characteristics that would be easy to operate and adjust. Such a consumer oriented night vision device would have wide ranging application in regard to nighttime marine piloting, nighttime security, surveillance, hunting, fishing, backpacking, navigation, underwater vision, search and rescue and law enforcement. 
     ITT Corporation, the assignee herein, manufactures many night vision devices for various applications. Night vision devices for military applications are exemplified by U.S. Pat. No. 5,084,780 to Phillips entitled TELESCOPIC SIGHT FOR DAY/NIGHT VIEWING and U.S. Pat. No. 5,029,963 to Naselli entitled REPLACEMENT DEVICE FOR A DRIVER&#39;S VIEWER. ITT Corporation, also has designed handheld night vision binoculars devices. Such a binocular device is exemplified in U.S. patent application Ser. No. 07/954,006, entitled CONSUMER NIGHT VISION VIEWING APPARATUS and filed on Sep. 30, 1992. In this application, a night vision binocular device is disclosed having simplified adjustment controls, interpupillary adjustments and diopter cell focus adjustments. Related optical components that can be utilized in the construction, of night vision binocular devices are shown in U.S. patent application Ser. No. 08/039,755 now U.S. Pat. No. 5,317,397 entitled DIOPTER CELL ASSEMBLY FOR A BINOCULAR VIEWING SYSTEM, and U.S. Pat. No. 5,117,553, entitled COLLIMATOR FOR A BINOCULAR VIEWING SYSTEM, both of which are assigned to the assignee herein. These references show a diopter cell design and a collimator lens assembly for night vision binoculars, respectively. The assignee holds many other patents and applications related to image intensifier tubes and related devices which are of interest in regard to the present subject matter. 
     As has been previously mentioned, an important application for publicly available night vision devices is on recreational boats. Boats often run at night utilizing only their running lights for illumination. The use of night vision devices by the pilots of boats will greatly increase visibility, resulting in less nighttime collisions and similar accidents. The night vision binoculars will enable boaters to identify objects detected on radar, see land marks, read channel markers, detect navigational hazards, identify approaching vessels and much more. The environment of a recreational boat is less than ideal for a sophisticated electro-optical device such as a handheld night vision instrument. To survive in such an environment, the night vision instrument must be capable of withstanding large temperature changes, impacts, and must be hermetically sealed to withstand the high humidity environment and the possibility of being dropped into the water. Furthermore, since most recreational boats are small, inexpensive craft, the night vision device must provide the same performance as military specification night vision devices but at a greatly reduced cost so as to be affordable to the average boater. 
     It is therefore the object of the present invention to provide a night vision device that is easy to hold, easy to operate, water proof and provides the same performance as military night vision devices at a greatly reduced cost. 
     It is a further object of the present invention to provide component parts for the above-mentioned night vision device that are easy to manufacture and assemble, thereby further reducing the cost of manufacturing the night vision device. 
     SUMMARY OF THE INVENTION 
     The present invention is a night vision binocular assembly capable of converting low intensity light and infrared energy into a visible image. The night vision binocular assembly includes at least one objective lens assembly, image intensifier tube, collimator lens assembly and diopter cell assembly encased in an easy to assemble waterproof housing The objective lens assembly, image intensifier tube, collimator lens assembly and diopter cell assembly are all supported by a common optical base or bed structure within the housing. As a result, variations caused by thermal expansions and contractions are evenly distributed among the various optical elements, thereby preserving a predetermined optical relationship between those elements. 
     Simple button controls are used to operate and adjust the night vision binocular assembly. The button controls include an on/off switch, a brightness switch and a focus switch, all of which being surface mounting switching elements that are disposed on a common circuit board within the binocular housing. An elastomeric planar sheet having domed sloped integral switching actuating projections is disposed between the circuit board and the interior of the binocular housing. The circuit board is affixed to the interior of the binocular housing in a manner that engages the elastomeric structure. The elastomeric structure is glued by means of a waterproof epoxy or adhesive to the internal surface of the housing and is held and maintained in position by a plurality of pegs extending on looping extensions which align the elastomeric switch sheet with the circuit board. The domed projections of elastomeric structure extend through apertures in the binocular housing creating both a fluid impermeable seal with the housing and with the domed projections providing a means for the tactile engagement of the switching elements on the circuit board. 
     The present invention night vision binocular assembly is manufactured in a manner that promotes both ease of use and ease of assembly. The primary optical elements of the night vision binoculars all interconnect onto the common optical base or bed structure with a minimal number of mechanical fasteners. The diopter cell assemblies require no mechanical fasteners in their assembly and the binocular housing can be assembled to be water tight without the use of a gasket. As a result, the present invention night vision binoculars can be manufactured and assembled in a highly reliable and cost efficient manner, thereby making the night vision binoculars affordable to the general consuming public. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     For a better understanding of the present invention, reference may be had to the following description of an exemplary embodiment thereof considered in conjunction with the accompanying drawings in which: 
     FIG. 1 is a front perspective view of one preferred embodiment of the present invention night vision binocular assembly; 
     FIG.2 is an exploded view of the embodiment shown in FIG. 1 to facilitate consideration ad discussion; 
     FIG. 3 a  is a cross-sectional view of a section of the housing of the present invention binocular assembly, shown prior to assembly; 
     FIG. 3 b  a cross-sectional view of a section of the housing of the present invention binocular assembly, shown after assembly; 
     FIG. 4 is an exploded view of the electro-optical subassembly contained within the present invention binocular assembly; 
     FIG. 5 is an exploded view of a diopter cell subassembly contained within the present invention binocular assembly; 
     FIG. 6 is a cross-sectional view of the region of the present invention binocular assembly containing the diopter cell subassembly, viewed along section line  6 — 6  as expressed in FIG. 1; and 
     FIG. 7 cross-sectional view of the image intensifier tube contained within the present invention binocular assembly, viewed along section line  7 — 7  as expressed in FIG. 4, and 
     FIG. 8 is a block diagram illustrating the electrical operations of the present invention binocular assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, there is shown one preferred embodiment of the present invention night vision binoculars  10 . As will be explained, the night vision binoculars  10  have a single objective lens for receiving infrared and low intensity light and two eye piece assemblies  12 ,  14  for viewing a visible image created from the received light. As will be later explained, the objective lens and the two eyepiece or ocular assemblies  12 ,  14  are adjustable to the physical and optical needs of the viewer that is utilizing the night vision binoculars  10 . 
     The optics and electronics of the night vision binoculars  10  are encased in a waterproof housing  16 . The housing  16  itself includes a upper half or section  18  and a lower half or section  20  that are joined together to create a fluid impermeable seal  21  along a line defined by the peripheral edges of sections  18  and  20  when the sections are coupled together. The housing  16  is preferably made of a material that is highly impact resistant, corrosion resistant and is light weight. In a preferred embodiment, the housing  16  is made of a thermoplastic material such as XENOY® PC/PBT resin alloy. However similar thermoplastic materials such as the XENOY®  2000 &amp; 5000  Series thermoplastic alloys can also be used. These generally are polyester bond urethanes. These thermoplastics are supplied by the General Electric Company via the GE Plastics Division. Such materials are light weight and provide the needed corrosion resistance and impact resistance. Furthermore, such materials can be manufactured in a variety of bright colors. It is desirable to produce the night vision binoculars  10  with a brightly colored housing to facilitate the location of the binoculars should they be misplaced or accidentally dropped into a body of water such as a lake or the ocean. The water tight housing  16  of the night vision binoculars  10  is sized to make the night vision binoculars  10  buoyant. Furthermore, the components of the night vision binoculars  10  are so distributed within the housing  16  so that the night vision binoculars  10  will float in the upright position shown in FIG. 1 or in the upside down position. This exposes the maximum surface area of housing  16  which floats above the water and thereby making the binoculars  10  more easy to spot in the water. 
     Since the water tight housing  16  is preferably a thermoplastic material, the housing  16  is relatively rigid. To enhance the impact resistance of the night vision binoculars  10 , elastomeric material in the form of eyeshades  22 ,  24  are placed around each of the eyepiece assemblies  12 ,  14 . Similarly, a elastomeric bumper  26  is disposed around the objective lens of the night vision binoculars  10 . The elastomeric material at these positions helps absorb the energy of an impact should the binoculars  10  be dropped. By placing the elastomeric material around the region of the eyepiece assemblies  12 ,  14  and the objective lens, it is less likelt that the force of impact will be transferred to these optical elements with enough energy to damage these elements. Furthermore, the elastomeric eyeshades  22 , 24  surrounding each of the eyepiece assemblies  12 ,  14  shade a persons eyes from secondary light and provide comfort when viewing through the night vision binoculars  10 . 
     Some of the electronic components contained within the night vision binoculars  10  are controlled by actuatible elastomeric switch projections employed as actual buttons that extend through associated apertures in the upper half  18  of the housing  16 . The control buttons include an on/off button  28  for controlling the activation and deactivation of the binoculars  10 , a focus button  30  for controlling the focus conjugate of the objective lens and a set of two brightness buttons  31  for controlling the brightness of the viewed image. 
     As will be later explained, the night vision binoculars  10  are manufactured with one set power of magnification. The night vision binoculars  10  may also be joined with a supplemental magnification lens  32  to increase the power of magnification. For instance, the night vision binoculars  10  may come with an initial power of magnification of 3× however when the supplemental magnification lens  32  is added, the power of magnification may be increased to 8×. The supplemental magnification lens  32  shown has a threaded end  34  that engages the night vision binoculars  10 . Such interconnections systems are well known for joining telephoto lenses to cameras and any such known interconnection system may be employed. Similarly, interference fit connections or other such mechanical interconnection systems may also be employed. 
     Referring to FIG. 2 in conjunction with FIG. 1, it can be seen that domed projections creating the on/off switch  28 , focus button  30  and brightness control buttons  31  are all unistructurally formed from single molded piece of elastomeric material. The elastomeric structure  36  is water impermeable and the various domed projections are formed in the elastomeric structure  36  so that they pass through associated button aperatures  37  in the upper half  18  of the housing  16 . Some identifying indicia may be molded onto the buttons to help a person easily identify the function of the button. A circuit board  38  is disposed against the elastomeric structure  36  within the housing  16 . Membrane switches, such as keyboard type switches  40 , or other pressure sensitive switches are disposed on the circuit board  38  directly below the on/off button  28 , focus button  30  and brightness control buttons  31 . As a result, as the on/off switch  28 , focus button  30  or brightness control buttons  31  are depressed, the membrane of the switch is actuated thus closing or opening the switch. These switches are bipolar as normally open or normally closed and when activated operate in the opposite state (ON or OFF) thus a corresponding signal is generated within the circuitry of the circuit board  38  by the below lying pressure switch  40 . 
     Connecting apertures  41 ,  42  are disposed in the elastomeric structure  36  and the circuit board  38 , respectively. In one embodiment, locking pegs or extensions  44  extend downwardly from the upper half  18  of the housing  16 . The elastomeric sheet or structure  36  with the extending elastomeric domed buttons  28 ,  30  and  31  is placed over the plurality of pegs or locking extensions  44  via the apertures  41 , so that it is precisely located due to the plurality of spaced pegs and apertures. The elastomeric structure  36  is glued securely in place to the housing by means of a waterproof adhesive such as methyl acrylate or a similar viscous waterproof epoxy. As a result, the elastomeric structure  36  is joined to the housing section  18  and provides a water tight seal. The locking extensions  44  pass through the connecting apertures  41 ,  42  in the elastomeric structure  36  and the circuit board  38 , wherein the locking extensions  44  are heat sealed or otherwise formed to secure and locate the circuit board  38  proper position with respect to the elastomeric structure. As a result, the elastomeric structure  36  is retained between the circuit board  38  and the upper half  18  of the housing  10  assisting in the invention of a water impermeable seal with the housing  16 . The resultant compression of the elastomeric structure  36  helps the elastomeric structure  36  to further act as a gasket and create a seal around each of the button apertures  37 . Consequently, should the night vision binoculars  10  be submerged in water, the water cannot enter the housing  16  through the button apertures  37  in the housing  16 . It will be understood that the use of a plurality of locking extensions  44  is merely exemplary and the circuit board  38  uses may be joined to the housing  16  using other schemes. In any event, the above techniques is extremely effective and inexpensive as the elastomeric structure when glued in position and located by the locking extensions automatically is aligned with the membrane switches  40  on the board  38  and forms a waterproof cover and seal for both the board and the housing. 
     As can be seen from FIG. 2 the upper half  18  and the lower half  20  of the binocular housing  16  join together along a complex peripheral path which path is defined by the peripheral edge of the corresponding openings of the upper and lower housing halves  18  and  20 . However, it is necessary to join the upper half  18  and the lower half  20  of the housing  16  together to create a fluid impermeable seal along the common joint  21  (FIG.  1 ). Such a seal may be accomplished through the use of a suitably shaped gasket placed between upper half  18  and the lower half  20  of the housing  16 . However, due to the complex shape of the peripheral edges, a gasket that would operate to join and seal the edges would be expensive to manufacture and highly labor intensive to install. Thus, in order to avoid the use of a gasket the peripheral edge of the upper housing section  18  is formed with a depending peripheral projection ( 46  of FIG. 3A) while the corresponding edge of the lower housing section  20  is provided with a corresponding peripheral groove ( 50  of FIG.  3 A). The projection and groove are specially shaped to enable an inner seal formation as will be further explained when referring to FIGS. 3A and 3B. In this manner, when the top housing section  18  is placed in congruency with the bottom housing section  20  the projection engages the groove to enable insertion of the top half housing section  18  into the lower half. As will be explained, both the projection  46  and groove  50  are specially shaped to contain a suitable adhesive enabling an inner peripheral housing seal to be formed to thus provide a waterproof seal for the housing  10  between the upper and lower halves without the need for a gasket. Referring to FIG. 3 a , there is shown a section of the upper half  18  of the housing  16  just prior to its being inserted into the corresponding groove of the bottom half  20  of the housing  16 . The upper section  18  of the housing  16  has a projection  46  extending downwardly therefrom. The bottom surfaces  48 ,  49  on either side of the projection  46  lay in two different planes with the bottom surface  48  proximate the exterior of the housing being higher than the bottom surface  49  proximate the interior of the housing. The lower section  20  of the housing  16  has a shaped groove or receptacle  50  formed along the edge that faces the upper section  18  of the housing  16 . The top surfaces  51 ,  52  on either side of the receptacle  50  also lay in two different planes with the top surface  51  proximate the exterior of the housing being higher than the top surface  52  proximate the interior of the housing. For a purpose which will later be explained, the receptacle  50  on the lower section  20  of the housing  16  is sized to be significantly larger than the projection  46  extending from the upper section  18  of the housing  16 . 
     Prior to the upper section  18  of the housing  16  being joined to the lower section  20 , an adhesive  54  is applied within the groove  50  of the lower section  20 . The adhesive  54  is material that bonds to the thermoplastic material of the housing  16  and cures to become water impermeable. A suitable and preferable adhesive contains methyl acrylate as a component which can be applied and employed similar to an epoxy using an activator which is mixed with the adhesive material. Such materials are available from ITW adhesive systems, of 30 Endicatt Street, Danvers, Mass. 01923. There are other adhesives which will operate as well. The adhesive has to be relatively viscous and hence not pour but act as an epoxy as being thick so it can be extruded to form the seal. Referring to FIG. 3 b , it can be seen that as the upper section  18  of the housing  16  is joined to the lower section  20 , a larger gap  55  is created proximate the interior of the housing than is created proximate the exterior of housing. As a result, the adhesive  54  present between the upper section  18  and the lower section  20  is directed toward the inside of the housing structure. Excess adhesive that is extruded from the joint creates a bead  56  on the inside of the housing. The bead  56 , created by the surface tension of the adhesive  54 , covers the entire joint along the inside of the housing  16 . Notches  57 ,  58  are disposed on the upper section  18  and the lower section  20  of the housing  16  at points proximate the exterior of the housing  16 . As the upper and lower sections  18 ,  20  arc joined, a semi-rectangular relief  59  is formed on the exterior of the housing  16  that runs along the joint between the upper and lower sections  18 ,  20 . Excess adhesive  54  that is extruded from the joint fills the back of the semi-rectangular relief  59  thereby providing a clean assembly without a highly visible line of adhesive. The presence of the adhesive  54  between the upper and lower section  18 ,  20 , in the semi-rectangular relief  59  and along the bead  56  inside the housing  16 , creates a barrier that hermetically seals the interior of the housing  16 . Once the adhesive  54  cures, a fluid impermeable seal is created between the upper and lower sections  18 ,  20  of the housing  16  without the use of a gasket. As a result, the upper and lower sections  18 ,  20  of the housing  16  can be joined in a cost effective and labor efficient manner. 
     Returning to FIG. 2 primary electrooptical subassembly  60  is shown and to be positioned within the internal hollow of the housing below the circuit board  38 . The electro-optical subassembly  60  includes an objective lens assembly  62  for receiving and focusing infrared energy, an image intensifier rube  64  for converting the infrared energy from the objective lens  62  into a visible image, a collimator lens assembly  66  for collimating the visible image, a beam splitter  67  for dividing the collimated image and two diopter or ocular cell assemblies  68 ,  70  through which the divided image is viewed with binocular vision. Each housing half section  18  and  20  have partial apertures which form full window apertures as  74  and  72  when the housings sections or halves are secured or joined together. Accordingly, window apertures  72 ,  74  are formed in the housing  16 . The aperture  72  aligns with the objective lens assembly  62  allowing infrared energy to pass into the housing  16  and impinge upon the objective lens assembly  62 . A protective window  75  is positioned within the aperture  72  through which the infrared energy passes. The window  75  is secured to the housing  16  with a fluid impermeable seal or adhesive thereby preventing the flow of water into the housing  16  through the aperture  72 . In a similar arrangement, two viewing apertures  74  align with the diopter cell assemblies  68 ,  70  to provide the ocular viewing paths. Protective windows  76  are positioned within the view apertures  74 . The protective windows  76  are joined to the housing  16  with a fluid impermeable seal, (using the above described adhesive), thereby isolating the environment contained within the housing  16 . A light sensor  65  is disposed within the housing  16 . The light sensor  65  senses light through an aperture  69  in the housing  16 . The complete aperture  69  is formed when housing sections  18  and  20  are joined together. The aperture  69  is aligned along an axis parallel to the longitudinal axis or optical axis of the objective lens assembly  62  As such, the light sensor  65  operates detect the intensity of radiant energy that is impinging upon the objective lens assembly  62 . This enables one to operate circuitry to block or deactivate the image intensifier tube  64  for excessive light levels which could damage the screen of the tube. See for example, U.S. Pat. No. 5,146,077 entitled “GATED VOLTAGE APPARATUS FOR HIGH LIGHT RESOLUTION AND BRIGHT SOURCE PROTECTION OF IMAGE INTENSIFIER TUBE by Casert et al, issued on Sep. 8, 1992 and assigned to the assignee herein. That patent describes protection circuits as well as describing GEN II and GEN III image intensifiers. A protective window  63  covers the aperture  69  in a fluid impermeable manner, thereby protecting the light sensor  65  and the interior of the housing  16  from moisture and other contaminants. 
     Referring to FIG. 4 in conjunction with FIG. 2 it can be seen that the objective lens assembly  62 , image intensifier tube  64 , collimator lens assembly  66  and diopter cell assemblies  68 ,  70  all are supported by a common optical base or support structure  80 . The common optical base  80  is “T” shaped having the top arm of the “T” of a planar configuration with a right and left slots  98  and  99  positioned on either side of the central arm of the “T”. The central arm is of a semi-cylindrical shape extending from the top arm and for accommodating the objective lens, the image intensifier and so on. Because of the common base configurations thermal expansion or contraction caused by a change in temperature will cause the objective lens assembly  62 , image intensifier tube  64 , collimator lens assembly  66  and diopter cell assemblies  68 ,  70  to be integrally effected thus maintaining the exact alignment for all such changes. As a result, the distances between the optical components remains generally constant, eliminating distortions that could be caused by uneven thermal expansions and contractions. In the preferred embodiment the casings surrounding the lenses in the objective lens assembly  62 , collimator lens assembly  66  and diopter cell assemblies  68 ,  70  have the same general coefficient of thermal expansion as does the base structure  80  so as to promote a uniform response to any change in temperature and maintain the preset relationships between the various optical components. A suitable material for the common optical bed or base  80  is a poly carbonate plastic. 
     In the shown embodiment, the beam splitter  67  is coupled to the collimator lens assembly  66  and is attached to the optical base structure  80  by a semicircular clamp  81 . The casing  82  of the collimator lens assembly  66  has a flat region  83 . Similarly, the semicircular clamp  81  also has a flat region  84 . Consequently, as the collimator lens assembly  66  is connected to the base structure  80  by the semicircular clamp  81 , the two flat regions  83 ,  84  align and the collimator lens assembly  66  with beam splitter  67  are automatically held in a predetermined set orientation. As such, by simply clamping the collimator lens assembly  66  to the base structure  80 , the collimator lens assembly  66  and beam splitter  67  are properly optically aligned with the other optical elements within the binocular housing. Collimator lens assemblies for night vision binoculars are known devices as is exemplified by U.S. Pat. No. 5,117,553 to Phillips entitled COLLIMATOR FOR A BINOCULAR VIEWING SYSTEM and assigned to ITT Corporation the assignee herein. This patent is incorporated herein by reference. The operation of collimator lens assemblies are well known. 
     An image intensifier tube  64  interconnects with the distal end  85  of the collimator lens assembly  66 . Although the image intensifier tube  64  can be of any type, in the preferred embodiment, the image intensifier tube is similar to a Generation II (GEN II) tube of a type manufactured by ITT Corporation, the assignee herein. In the shown embodiment, the image intensifier tube  64  has an elastomeric casing ( 86  of FIG.  7 ). The base structure  80  includes an enclosed tubular region  87  that has a diameter slightly smaller than the elastomeric casing  86  of the image intensifier tube  64 . The elastomeric casing  86  of the image intensifier tube  64  passes into the enclosed tubular region  87  where it is retained by an interference fit. The lateral movement of the image intensifier tube  64  back and forth within the enclosed tubular region  87  is prevented by the interference fit and the abutment of the image intensifier tube  64  against the collimator lens assembly  66  and the sleeve  90  surrounding the objective lens assembly  62 . 
     The objective lens assembly  62  is surrounded by a circular sleeve  90  in such a manner so that the objective lens assembly  62  is free to move axially or reciprocate along the longitudinal axis of the tubular sleeve  90 . An aperture  91  is formed in the peripheral wall of the tubular sleeve  90 . A stop block  92  is connected to the objective lens assembly  62  and extends radially away from objective lens assembly  62  through the aperture  91 . As such, the stop block  92  contacts the edges of the aperture  91  as the objective lens assembly  62  moves back and forth. As a result, the stop block  92  limits the axial movement of the objective lens assembly  62  along the longitudinal axis of the tubular sleeve  90 . 
     Locking projections  93  extend radially from the tubular sleeve  90 . The locking projections  93  engage locking slots  94  formed in the tubular region  87  of the base structure  80 . By passing the projections  93  into the locking slots  94  and turning the tubular sleeve  90  relative the base structure  80 , the tubular sleeve  90  is locked into a desired set position on the base structure  80 . 
     A stepper motor  95  is connected to the base structure  80 . The stepper motor  95  has extending flanges  195  and  196  which enable the body of the motor to be inserted into the aperatures  200  of motor bracket  201  formed integrally or otherwise located on the common optical bed  80 . The flanges  195  and  196  of the motor  95  are secured to the bracket  201  via apertures  202 . The shaft  96  of the motor as indicated is coupled to the stop block  92  to thus move the objective lens  62  according to the motor operation. The stepper motor shaft  96  interconnects with the stop block  92  extending from the objective lens assembly  62  As will later be explained, the stepper motor  95  can be activated to move its shaft  96  back and forth in the directions of arrow  97  utilizing incremental steps. This movement moves the objective lens assembly  62  within the tubular sleeve  90 , which therefore moves the lens  62  in relation to the image intensifier tube  64 . Small stepper motors capable of moving in small increments such as 0.0005 inches to 0.004 inches per step are commercially available such as those manufactured by Haydon Switch Instruments, Inc. of Connecticut and sold under the designation HSI miniature motors. 
     A position sensor such as a micro switch or pressure optical switch  148  is attached to the optical base structure  80  proximate to the stepper motor  95 . The position sensor  148  is contacted by the stop block  92  as the stepper motor  95  moves the stop block  92  back and forth. The distance between the position sensor  148  and the stop block  92  is set so that the position sensor  148  is triggered when the stop block  92  moves the objective lens assembly  62  to a position relative the image intensifier tube  64  to image the incoming energy at an infinite conjugate. 
     As indicated, slots  98 ,  99  are formed in the upper arm of the “T” sloped base structure  80 . A mechanical fastener  100  or other similar element joins each of the diopter call assemblies  68 ,  70 , to slide blocks  101 ,  102  through the slots  98 ,  99 . As a result, each of the diopter cell assemblies  68 ,  70  is joined to the base structure  80 , yet sill can move along the length of each of the slots  98 ,  99 . The purpose of each of the diopter cells  68 ,  70  is to redirect light emanating from the collimator lens assembly  66  and split by the beam splitter  67  into the viewer&#39;s eyes. 
     Referring to FIG. 5, it can be seen that each of diopter cell assemblies is a snap-together assembly requiring no adhesives or mechanical fasteners. FIG. 5 shows one of the diopter cell assemblies  68  as used in the present invention night vision binoculars. Each cell is identical. Light (designated by the arrows) entering the diopter cell assembly  68  passes through a first lens  105 , where it is reflected 45° by a mirror  106  and redirected through an ocular lens  107 . The first lens  105  and the mirror  106  are both connected to a common cell housing  108 . The cell housing  108  has a face surface  109  through which an aperture  110  is formed. The aperture  110  has a stepped rim sized to accommodate the first lens  105 . As a result, the first lens  105  can pass into, and become seated within, the aperture  110 . A snap-on cover  112  connects to the cell housing  108  over the first lens  105 . The cover  112  has an aperture  111  formed through it that is smaller than the diameter of the first lens  105 . Consequently, when the cover  112  is joined to the cell housing  108 , the fast lens  105  becomes entrapped in a set position between the cover  112  and the cell housing  108 . The aperture  111  in the cover  112  is positioned to enable light to pass into the first lens  105  and into the cell housing  108 . Pawl receptacles  113  are formed on the cell housing  108  at points proximate the face surface  109 . The cover  112  has locking pawls  114  that extend into and engage the pawl receptacles  113  on the cell housing  108 , thereby interconnecting each of the two components with a snap fit. 
     Within the cell housing  108  a 45° sloped surface  116  extends between two side walls  117 ,  118 . An aperture  119  is disposed in the sloped surface  116  at a position that aligns with the aperture  110  in the face surface  109  of the cell housing  108 . The mirror  106  lays across the sloped surface  116  covering the aperture  119  in the sloped surface  116 . The mirror  106  is held in one set position over the sloped surface  116  by a black plate  120 . Projecting arms  122  extend from the four corners of the backplate  120 . These projecting arms  122  engage notches  124  formed in the side walls  117 ,  118  as the back plate  120  passes between sidewalls  117 ,  118 . The position of the notches  124  and the size of the back plate  120  correspond so that the back plate  120  engages the notches  124  with a slight interference fit, thereby enabling the projecting arms  122  to snap fit into the notches  124  and retain the backplate  120  in one set position. The backplate  120  biases the mirror  106  against the sloped surface  116 , thereby retaining the mirror  106  over the aperture  119  in the sloped surface  116 . 
     The mirror  106  directs light passing through the first lens  105  into the tubular region  125  of the cell housing  108 . The tubular region  125  of the cell housing  108  is sized to receive a sliding collar  126  therein. Referring to FIG. 6 in conjunction with FIG. 5, it can be seen that the sliding collar  126  is a tubular structure that has locking fingers  128  proximate its distal end The ocular lens  107  is inserted into the sliding collar  126  wherein the locking fingers  128  engage the lens  107  and forces the lens against an internal rim structure  129 . As a result, the locking fingers  128  retain the lens  107  into a set position within the sliding collar  126 . A key projection  130  extends radially from the exterior surface of the sliding collar  126 . The key projection  130  has width W 1  (FIG. 5) that is slightly smaller than the width W 2  of a corresponding slot  132  in the cell housing  108 . The sliding collar  126  fits within the tubular region  125  of the cell housing  108  wherein the key projection  130  enters the slot  132 . The sliding collar  126  is free to move back and forth within the cell housing  105  provided the key projection  130  does not contact the back edge  131  of the slot  132 . The presence of the key projection  130  in the slot  132  prevents the sliding collar  126  from rotating within the cell housing  108 ; to thus retain the viewing lens  107  in its proper orientation as it is moved back and forth with the sliding collar  126 . 
     An adjustment shaft  134  also extends radially from the exterior of the sliding collar  126 . The adjustment shaft  134  passes into a second slot  135  in the cell housing  108  as the sliding collar  126  is positioned within the cell housing  108 . As the overall diopter cell  68  is assembled within the night vision binoculars, the adjustment shaft from each of the two diopter cells aligns with slots  77 , formed in the bottom of the lower half of the housing as is shown in FIG.  2 . Adjustment knobs  137  extend through each of the slots  77  in the housing and engage the adjustment shafts  134 . As can be ascertained from FIG. 6, the adjustment knobs  137  can be moved back and forth in the directions of arrow  138  and also back and forth into and out of the plane of the paper. As the adjustment knobs  137  are moved back and forth in the directions of arrow  138 , the sliding collar  126  is caused to move back and forth within the cell housing in the same direction. This changes the position of the ocular lens  107  with respect to the other optical elements in the binoculars. Consequently, the movement of the ocular lenses  107  acts as a focus adjustment, whereby the binoculars can be individually adjusted for each eye. As the adjustment knobs  137  are moved back and forth into and out of the plane of the paper, each of the diopter cell assemblies are caused to move with the adjustment knobs  137 . Such a manipulation various the distance in between the diopter cell assemblies thereby providing an interpupillary adjustment to the night vision binoculars. The movement of the adjustment knobs  137  causes the diopter cell assemblies to move back and forth in the slots  98 ,  99 , shown in FIG.  4 . As a result, the distance between each of the diopter cell assemblies and the beam splitter can be varied indvidually and the diopter cell assemblies can be individually adjusted as desired. This type of operation interpupillary adjustment and focus is described in the copending application Ser. No. 07/954,006 indicated above. Elastomeric grommets  133  seal the slots  77  around each of the adjustment knobs  137 , thereby creating a fluid impermeable seal that prevents water and other contaminants from entering the binocular housing. The grommets are secured to the housing by adhesive seals. 
     Referring now solely to FIG. 2, the optical operation of the night vision Binoculars  10  can be described. To activate the night vision binoculars  10 , the on/off button  28  is depressed. Upon activation, the stepper motor  95  is enabled whereby the stepper motor  95  focuses the objective lens assembly  62  at a generally infinite conjugate. The focus of the objective lens assembly  62  can be changed by the manipulation of the focus button  30 . By depressing either side of the focus button  30 , the stepper motor  95  can be controlled in a manner that provides a variable adjustment to the objective lens assembly  62  between an infinite conjugate and a conjugate of one meter. For example, by depressing the elastomeric switch activator or button on the left side, the stepper motor rotate the shaft  96  counter clock wise (CCW) to cause the motor shaft  96  to move forward and by depressing the elastomeric switch activator the right side the motor move clock wise (CW) to cause the motor shaft to move in the appropriate direction of vice versa. 
     Infrared or low intensity visible light is directed through the objective lens assembly  62  onto the image intensifier tube  64 . The image intensifier tube  64  produces a visible image which is then directed to the collimator lens assembly  66 . The brightness of the image produced by the image intensifier tube  64  is controlled by the manipulation of the brightness buttons  31 . By depressing one of the brightness buttons  31 , the gain of the image intensifier tube  64  can be increased or decreased, thereby increasing or decreasing the brightness of the image produced. Brightness controls for image intensifiers are well known. Since the image intensifier tube  69  is highly sensitive to light, a light sensor  65  is also made part of the night vision binoculars assembly. The light sensor  65  is coupled to a control circuit on the circuit board  38  that compares the detected light level to a threshold level and automatically turns off the image intensifier tube  64  should the threshold light level be surpassed. 
     The image produced by image intensifier tube  64  is directed through the collimator lens assembly  66  that reimages the image at a generally infinite conjugate. The conjugated image is then split in two by the beam splitter  67  and directed toward the two diopter cell assemblies  68 ,  70 . The split image passes through each of the diopter cell assemblies where it is viewed with binocular vision and focused to the requirements of the user. The focusing and interpupillary positioning of each of the diopter cell assemblies  68 ,  70  is controlled by the adjustment knobs  137  as has been previously explained. 
     Referring to FIG. 7, a cross section of one preferred embodiment of the image intensifier tube  64  and its elastomeric casing  86  are shown Although the image intensifier tube  64  can be of any known design, it is preferably a GEN II image intensifier tube. The operation of the GEN II image intensifier tube is known in the art. In the shown embodiment, the image intensifier tube  64  is a type of GEN II tube that has been modified to be produced at a much lower cost than typical GEN  11  tubes for military applications. The image intensifier tube  64  has a photocathode  71 , microchannel plate  73 , and a optical window  77  coated with a phosphor screen  78 . To operate the image intensifier tube  64  various known electrical biases are applied to the photocathode  71 , microchannel plate  73  and phosphor screen  78  to promote the flow of electrons from the photocathode  71  to the phosphor screen  78 . In the prior art, electrical potentials were supplied to these components utilizing connector pins that extended into the evacuated housing of the image intensifier tube. Typically, the connector pins were disposed as far away form one another as possible to prevent any arcing from occuring between the various connector pins. In the shown embodiment, electrical bias is supplied to the photocathode  71 , microchannel plate  73 , and phosphor screen  78  via conductive annular flanges  79  that radially extend from the image intensifier tube  64 . Wires  88  are then joined to the annular flanges  79  at the most convenient point and need not be directed to a single connector pin. 
     The elastomeric casing  86  that surrounds the image intensifier tube  64  is molded around the image intensifier tube  64 . As such, the elastomeric material of the casing  86  fills the spaces between the various annular flanges  79 . The elastomeric casing  86  therefore acts to encapsulate each of the annular flanges  79  and electrically isolates the annular flanges  79  from one another. The elastomeric casing  86  further acts to encapsulate the interconnection point between the various annular flanges  79  and wires  88 , thereby deterring the wires  88  from detaching from the annular flange  79 . The glass input and output plates as  78  and  77  are the same exact configuration with the exception of the domed portion  89 . The annular connecting rings and the plate shape enable a inexpensive tube to be provided. 
     Referring to FIG. 8, there is shown a block diagram detailing the operational logic for the electrical components of the present invention night vision binoculars. As has been previously described, the optical components of the night vision binoculars include an objective lens assembly  62 , and an image intensifier tube  64 , a collimator lens assembly  66  and at least one diopter cell assembly  68 . In the preferred embodiment, the night vision binoculars are a self contained transportable unit. As such, the power supply  141  to the binoculars are preferably batteries ( 224  of FIG.  2 ). Referring to FIG. 2, a battery housing compartment  223  in the bottom half section  20  accommodates a battery  224 . The battery  224  is held in the housing compartment  223  by a cover  225  having a flange  226  and gasket which seals the battery within the compartment  223 . The battery terminals are connected to terminals  228  and  228  which in turn operate to power the electronic components. The batteries can be disposable or rechargeable and are preferably widely commercially available. The on/off operation of the power supply  141  is controlled by the tactile manipulation of the on/off button  38  that is operational from the exterior of the binocular housing. 
     Referring again to FIG. 8 a  or suitable programmed logic array (PLA or PLD) controls the electrical operation of the night vision binoculars. The C.P.U.  144  is contained within the circuit board assembly  38  previously shown in FIG.  2 . Although several other functions may be incorporated, the C.P.U.  144  serves primarily as a voltage regulator control  142  a motor control  146  and brightness operative. A high voltage supply  150  is coupled to the C.P.U.  144 . The C.P.U.  144  directs current from the power supply  141  to the high voltage supply  150 , where the initial six volt power supply is amplified to the voltage requirements of the components within the image intensifier tube  64 . The voltage requirements of various image intensifier tubes are well known in the art and need not be disclosed in detail herein. Gain control buttons  31  are coupled to the C.P.U.  144 . The gain control buttons  31  control the operation of the high voltage supply  150 . As a result, by manipulating the gain control buttons  31 , the voltages supplied to the different components of the image intensifier tube  64  can be changed. By varying the voltages supplied to the image intensifier tube  64  the gain of the tube can be controlled, thereby controlling the brightness of the image that the image intensifier tube  64  produces. 
     The light sensor  65  is coupled to the C.P.U.  144 . The light sensor  65  detects the intensity of light that is impinging upon objective lens assembly  62 . The C.P.U.  144  reads the signal from the light sensor  65  and automatically adjusts the gain of the image intensifier tube  64  to optimize the contrast of the image being viewed. Furthermore, the C.P.U.  144  compares the signal from the light sensor  65  to a predetermined threshold valve. If the light sensor  65  detects a light intensity greater than the threshold valve, the gain controller  144  can deactivate the image intensifier tube  64  to prevent damage to the image intensifier tube  64 . 
     As has been previously described, the objective lens assembly  62  is coupled to stepper motor  95  that is capable of focusing the objective lens assembly  62  between an infinite conjugate and a conjugate of one meter. The operation of the stepper motor  95  is controlled by the motor drive  146 . The C.P.U.  144 , via the motor drive  146 , automatically focuses the objective lens assembly  62  to an infinite conjugate each time the night vision binoculars are turned on. Such an automatic adjustment is made utilizing a position sensor  148  that is coupled to the objective lens assembly  62 . The position sensor  148  signals the C.P.U.  144 , thereby deactivating the motor drive  146  when the objective lens assembly  62  is properly focused at an infinite conjugate. Adjustments away from the infinite conjugate are made via the focus control buttons  30  that cause the motor drive  146  to advance the stepper motor  95  and change the position of the objective lens assembly  62 . 
     An LED  123  is disposed in the diopter cell assembly  68  in a manner that enables the light from the LED to be viewed by the viewer. The LED  132  is coupled to the C.P.U.  144  and lights when the power supply  141  is drained, thereby indicating that the batteries are low to the viewer. 
     The above described night vision binocular device enables the amplification of light up to 20,000 times for optimum night viewing. The power focus and interpupillary adjustment ensure easy and simple operation. The apparatus with the battery is light and a typical device weighs less than 30 ounces and can float. The device is battery operated, provides a 40 degree flied of view (FOV) and has an automatic shut off to protect the image intensifier. The device is 7¾″ (length) 5½″ (width) and 2⅗″ (height). The casing is waterproof and impact resistant. 
     It will be understood that the night vision binocular assembly described herein is merely exemplary and that a person skilled in the art may make many variations and modifications to the described embodiments utilizing functionally equivalent components to those described. All such variations and modifications are intended to be included within the scope of this invention as defined by the appended claims.