Abstract:
The invention is a dual function laser device for use in night vision systems. The invention uses lenses to cause one portion of a laser beam to converge to a target point and another portion of the beam to diverge. The divergent portion is variable in size and illuminates a viewable area around the target point. Rather than use two lasers to create an illuminated view area around an illuminated target point, the invention uses a combination of a lens and a sub-aperture lens arrangement to create two illuminations from a single laser.

Description:
CROSS REFERENCE TO A RELATED APPLICATION 
     This application is copending with U.S. provisional application No. 60/150,283 filed Aug. 23, 1999. The benefit of the filing date of that application is hereby claimed. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to novel devices for illuminating a target with a coherent beam of radiant energy, typically, although not necessarily, operating in the covert, near infrared portion of the electromagnetic spectrum, and capable of functioning simultaneously as both a source of illumination and a pointing device. 
     In the interest of brevity and clarity, the principles of the present invention will be developed in large part with reference to target illumination and aiming. This is not intended to limit the scope of the invention as defined in the appended claims as there are many other applications of laser illuminators employing these principles such as medical technology or surveying. 
     BACKGROUND OF THE INVENTION 
     The invention disclosed here is an improvement on the type of night vision system disclosed in U.S. Pat. No. 5,056,097 entitled TARGET ILLUMINATORS AND SYSTEMS EMPLOYING SAME (“the &#39;097 patent”) which is hereby incorporated by reference into this specification. The &#39;097 patent disclosed a night vision target illumination device that uses a laser to provide illumination. The illumination device is an “infrared laser ” system. In other words, the laser is used to illuminate a target area that is invisible to the naked eye and can only be seen by viewing the target area through an image intensifier or other infrared sensing device. 
     An important advantage of a laser-based device over earlier designs (i.e., LED-based devices) is that the laser-based device can illuminate a target area at a much greater distance. Earlier LED-based devices were limited in their ability to produce adequate visual images at ranges approaching 500 feet and beyond. Laser-based devices are limited only by their power output. 
     The laser-based system can be built with a zoom function that allows adjustment of the size of the illuminated target area. Obviously, enlarging the target area gives the user a wider field of view. But, the laser can also be focused to a point (i.e., “target point”) and therefore function as an invisible targeting device (i.e., “gun sight”). 
     The use of visible lasers as gun sights for weapons targeting is, of course, well known and has been used by the military, police SWAT teams, and the like. They create a targeting point or spot (e.g., a red “dot”) that is visible to the naked eye. In the case of the invisible laser, the target point can be seen only through special infrared or night vision imaging devices. 
     If the invisible laser is focused to a small target point in the dark, then the user (who views the area illuminated by the laser through the night vision imaging devices) cannot see anything in the dark but the target point itself. Consequently, heretofore invented has been a dual laser system that uses one laser for the targeting point function and a second laser to create a larger, viewable field around the target point. By taking advantage of the features of the dual laser system, the user can see where the target point should be moved as necessary. 
     SUMMARY OF THE INVENTION 
     The present invention is an improvement over the dual laser system described above. 
     The invention disclosed herein is a dual function, single laser device. Rather than using two laser emitters, the device uses a single laser in combination with a unique arrangement of lenses to produce both a “targeting” function (pinpoint dot) and a variable sized “field of illumination” function as described above. This is accomplished by placing a first lens downstream of a laser diode for focusing the laser&#39;s beam along a converging path. A second lens arrangement is positioned within the envelope of the beam path and fans a portion of the beam outwardly along a diverging path. The first lens is used to focus a portion of the laser&#39;s beam to a target point for sighting purposes. The second lens arrangement causes a central portion of the beam to spread outwardly and create an illumination field around the target point. 
     The second lens arrangement can be made in different ways. One type of lens arrangement uses a pair of sub-aperture lenses positioned downstream of the first lens, but still within the “footprint” of the laser beam after it passes through the first lens. The specific details of this particular embodiment, and others, are described below. 
     The invention provides many advantages over existing laser-based devices. By using lenses to create both the targeting and viewing functions, one laser emitter can do the job of two. An advantage of using a single laser emitter is that a laser targeting device can be simplified and made at lower carrying weight and reduced cost relative to prior designs. When two laser emitters are used, each requires its own electronics and power. Therefore, reducing the number of emitters from two to one significantly simplifies the design, and reduces the cost of an invisible targeting device. 
    
    
     The objects, advantages, and features of the present invention will be apparent to the reader from the foregoing and the appended claims, and as the ensuing detailed description and discussion of the invention proceeds in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE VARIOUS VIEWS OF THE DRAWINGS 
     In the drawings, like reference numerals refer to like parts throughout the various views unless indicated otherwise, and wherein: 
     FIG. 1 is a pictorial view of a dual function single laser device of the present invention; 
     FIG. 2 is a cross-sectional view of the dual function single laser device, taken substantially along line  3 — 3  of FIG. 1, showing the internal functional components of the device; 
     FIG. 3 is an enlarged cross-sectional view of a portion of FIG. 2, showing a secondary lens in a retracted position; 
     FIG. 4 is an enlarged cross-sectional view like FIG. 3, showing a secondary lens in an extended position; 
     FIG. 5 is an illustration, showing the movement of the laser focusing assembly, shown with broken lines at  28  in FIG. 1 in response to rotation of the horizontal focusing knob; 
     FIG. 6 is like FIG. 5, and shows the movement of the laser focusing assembly in response to rotation of the vertical focusing knob; 
     FIG. 7 is a schematic illustration of the lens arrangement corresponding to focused dot mode; 
     FIG. 8 is like FIG. 7, and illustrates the lens arrangement corresponding to a simultaneous focused dot and flood mode; 
     FIG. 9 is like FIGS. 7 and 8, and illustrates the lens arrangement corresponding to another simultaneous focused dot and flood mode in which the illumination beam is expanded to encompass a greater area; 
     FIG. 10 illustrates the appearance of the beam produced by the lens arrangement shown in FIG. 7; 
     FIG. 11 illustrates the appearance of the beam produced by the lens arrangement shown in FIG. 8; 
     FIG. 12 illustrates the appearance of the beam produced by the lens arrangement shown in FIG. 9; 
     FIG. 13 is a schematic view of a lens arrangement that creates dual function illumination from the same laser diode; 
     FIG. 14 is a view similar to FIG. 13, showing a alternative lens configuration that may be suitable for providing the dual illumination function; 
     FIGS. 15-17 are views like FIGS. 13 and 14, showing still other alternative lens configurations. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, FIG. 1 depicts a dual function, single laser device (the “DFSL device”) of the present invention generally at  10 . The DFSL device  10  includes a main housing  12  and a battery housing  14 . Batteries (not shown) in this case supply the power for operating the DFSL device  10 , and may be inserted or removed from battery housing  14  via a removable closure cap  16  located near the proximal end of the battery housing. Battery housing  14  is removable from the main housing  12  and may be replaced by other optional battery housing elements designed to receive various types of batteries which the user may select based on size, weight or power longevity considerations. 
     Main housing  12  includes push button switch  20 , main switch  22 , vertical focusing knob  24 , horizontal focusing knob  26 , laser focusing assembly  28  (shown in broken lines), a rotatable type projection zoom lens  30 , and cover element  32  pivotally connected to projection zoom lens  30 . 
     Having observed the details of these basic components of the DFSL device  10 , attention may now be given to the functional interaction of these components with the internal system components of the present invention. Referring now to FIGS. 2-4, cross-sectional views of the DFSL device  10  of FIG. 1 are illustrated. 
     Batteries (not shown), contained in battery housing  14  provide a power source for electronics package  34  which in turn powers laser diode  36 . Because the electronics are not an aspect of the present invention, the reader is referred to a description of the laser driver module and power supply schematics in the &#39;097 specification. When the main switch  22  (see FIG. 1) has been placed in the “On”, or an operational position, laser diode  36  may be activated by user actuation of push button switch  20  or remotely via connection with a multipurpose arming plug  18  located on battery housing  14 . Multipurpose arming plug  18  must be engaged with a key plug (not shown) or its equivalent before the DFSL device can be activated via main switch  22  or push button switch  20 . 
     The illustrated DFSL device  10  is supplied with a 100 mW laser diode  36  operating at a frequency in the near infrared portion of the electromagnetic spectrum, or other device as the type used in the device disclosed in the &#39;097 specification. Laser diodes are familiar to those skilled in the art. When activated, the laser  36  emits a coherent stream of radiant energy  40  at a particular wavelength. The emitted radiant energy  40  passes through a main focusing bi-convex lens  38  wherein it is formed into a well defined beam  42 . This beam of radiant energy  42  is then passed through a primary lens assembly  44 . Primary lens assembly  44  includes a centrally-positioned, positive planar convex lens  46  within the envelope or “footprint” of beam  42 , and is supported at each end by lens holder  45 . Because lens  46  is positioned entirely within the “footprint” of beam  42 , a first portion of beam  42 , referenced in FIGS. 3 and 4 at  52 , passes through lens  46  and converges to focal point  48 . The remaining second portion of beam  42 , referenced in FIGS. 3 and 4 at  54 , passes around lens  46  through the planar, transparent portion  50  of primary lens assembly  44 . 
     Referring now specifically to FIGS. 2 and 3. Beam  46 , after having been passed through primary lens assembly  44 , is passed through a secondary lens assembly  56  which is fixedly connected to projection zoom lens  30  at circumferentially extending band  58 . The first portion  52  of beam  46  passes through negative planar convex lens  60  and diverges to create illumination beam  62 . As with lens  46 , lens  60  is positioned within the “footprint” of beam  42  and the second portion  54  of beam  42  passes around lens  60  through the planar, transparent portion  64  of secondary lens assembly  56  to create pointing beam  66 . 
     The down range diameter of the illumination beam  62  varies with the spaced relationship of secondary lens assembly  56  and primary lens assembly  44 . When projection lens  30  and attached secondary lens assembly  56  are in a fully extended position (see FIG.  4 ), the first portion  52  of beam  42  is refracted by lens  60  so that its path is parallel with the second portion  54  of beam  42  resulting in the creation of focused pointing beam  68  without a corresponding illumination beam. This spatial arrangement of the primary and secondary lens assemblies will be referred to as focused dot mode. 
     A set screw  70  provides a stop to prevent projection zoom lens assembly  30  from being overly extended or removed. O-ring  72  fits into a groove  74  machined into the exterior surface of main housing  12  prior to engagement with projection zoom lens assembly  30 . The O-ring  72  is employed to keep foreign material from penetrating between tubular housing  31  and guide member  76  of main housing  12 . 
     Referring now primarily to FIGS. 5 and 6, pointing beam  66  (see FIG. 2) creates a focused dot relative to an object downrange of the DFSL device. When used in the context of targeting, it is advantageous to provide a focusing feature with respect to the pointing beam  66  so that it can be adjusted relative to the impact point (i.e. from a bullet) to ensure complete targeting accuracy. To this end, vertical and horizontal focusing knobs  24 ,  26  provide an adjustment mechanism for beam alignment through click-stop movement. 
     Each focusing knob can be advanced or backed off by rotation of the respective knob in its threaded container (not shown). Rotation of vertical focusing knob  24  imparts a movement to laser focusing assembly  28  along axis  25 , while rotation of horizontal focusing knob  26  imparts a corresponding movement to laser focusing assembly  28  along axis  27 . The adjusted positions of laser focusing assembly  28  are illustrated in FIGS. 5 and 6 by broken lines as is the corresponding radiant energy  40  emitted from laser diode  36 . 
     Supporting ring member  29  (FIGS. 3-6) is fixedly connected to the inner surface  78  of guide member  76 . Focusing movement is imparted to the otherwise rigid structure of laser focusing assembly  28  by way of flex channels  80  machined into the surface of assembly  28 . 
     FIGS. 7-9 illustrate the spatial relationship between the primary and secondary lens assemblies  44 ,  56 , and the corresponding beam or beams of radiant energy resulting therefrom. FIG. 7 illustrates the relationship of the two lens assemblies in the focused dot mode wherein only a pointing beam  66  is generated. FIG. 8 illustrates one of a plurality of intermediate relationships between the two lens assemblies wherein both a pointing beam  66  and an illumination beam  62  are generated. These intermediate arrangements are realized by rotation of the projection zoom lens which in turn moves secondary lens assembly  56  toward primary lens assembly  44  as indicated by the arrow  82  in FIGS. 8 and 9. 
     FIG. 9 illustrates the spatial relationship of the lens assemblies when the projection zoom lens has been fully retracted, placing secondary lens assembly  56  in the nearest position in regard to the more divergent illumination beam  62  resulting in a wider “field of view” in the downrange beam appearance. 
     The downrange beam appearance resulting from each lens assembly arrangement in FIGS. 7-9 is illustrated in FIGS. 10-12 respectively. Pointing beam  66  appears as a focused dot, while illumination beam  62  has a diameter proportionate to its diverging angle  84  (see FIG. 9) as it passes from secondary lens assembly  56 . 
     Referring now to FIG. 13, shown generally at  90  is a lens configuration, similar to those illustrated in FIGS. 7-9, that will provide dual-function illumination from a single laser device. The position of the laser emitter is indicated at  92 . 
     Light from the laser emitter or diode at  92  passes through a first positive lens, indicated at  94 . The first lens  94  causes the light beam to converge downstream of the lens, as indicated generally at  96 . A pair of sub-aperture lenses  98 ,  100  are positioned downstream of the first lens, but within the envelope or “footprint” of the light beam  96 . Therefore, as described previously, a portion of the beam passes around the sub-aperture lenses while another portion passes through them. 
     The sub-aperture lenses  98 - 100  illustrated in FIG. 13 are “positive-negative” lenses. A person skilled in optics will be familiar with this terminology and the types of lenses used to create the effect that is illustrated. As mentioned previously, a portion of the light beam  96  passes through the first lens  98  of the sub-aperture arrangement and then converges toward and then diverges beyond a focal point  102 . The convergence is indicated at  104  and the divergence is indicated at  106 . The divergent portion  106  passes through the second sub-aperture lens  100  which “fans” that portion of the beam outwardly or divergently, as shown at  108 . 
     The portion of the beam  96  that does not pass through the sub-aperture lenses, indicated generally at  110  downstream of the sub-aperture lenses  98 ,  100 , continues to converge to a focal point  112 . The net effect is that the sub-aperture lenses fan a portion of the beam into a wider area of illumination, indicated by the bracket  114  in FIG. 13, while that portion of the beam that passes around the sub-aperture lenses  98 ,  100  is focused to a point. When the lens arrangement  90  is used as a targeting device with an invisible laser diode, the downstream focal point  112  can function as a highly precise gun sight, while the fanned area  114  allows the surrounding area to be viewed. 
     The lens arrangement illustrated in FIG. 13 is a preferred configuration for creating a dual-function laser as described above. However, the same dual function from a single laser diode may be achieved through the use of different lens arrangements. Examples of other lens configurations are illustrated in FIGS. 14-17. 
     Referring first to FIG. 14, the positive-negative sub-aperture lenses  98 ,  100  shown in FIG. 13 are replaced by an arrangement of positive-positive sub-aperture lenses  120 ,  122 . This particular arrangement moves the sub-aperture focal point  124  downstream of the lenses  120 ,  122 . The interior portion of the beam then fans outwardly from the focal point  124  to create the field of illumination indicated by bracket  126 . 
     The lens arrangement  130  shown in FIG. 15 may also be used to create a dual function effect. The first lens  132  has a bore or opening  134  extending through the lens in which a second lens  136  is placed. A portion of the second lens  136  is physically upstream of the first lens  132 . Second lens  136  captures an interior portion of the laser light  138  and fans it outwardly through the first lens  132 , as shown at  140 . The first lens  132  otherwise converges the remainder of the beam to a point  142 . 
     Still other lens configurations are illustrated in FIGS. 16 and 17. These represent configurations that may enable longer optical paths for targeting purposes. FIG. 16 illustrates a lens arrangement  150 ,  152  that is somewhat similar to the arrangement illustrated in FIG.  15 . However, upstream of lenses  150 ,  152  are a pair of positive re-imager lenses  154 ,  156 . The arrangement illustrated in FIG. 17 is a further variation on the arrangement illustrated in FIG.  16 . The FIG. 17 arrangement uses a positive-negative pair of re-imager lenses  158 ,  160  in combination with a smaller, downstream lens  162 . 
     While the invention is described and illustrated here in the context of a targeting device and with particular lens configurations, the invention may be embodied in many forms without departing from the spirit or essential characteristics of the invention. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.