Abstract:
A combined range finding and sighting apparatus for a weapon includes a housing therein supporting one or more laser emitters, an optical detector for detecting an optical signal reflected from the target, and a processor. The one or more laser emitters includes a first laser emitter operable in a first mode for emitting an optical signal toward the target a second mode for projecting a first beam onto the target. The processor is coupled to a computer readable memory encoded with executable instructions and is configured, upon execution of the executable instructions, to calculate a distance to the target based on a time of flight of the optical signal. In a further aspect, a method of using a combined range finding and sighting apparatus is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a non-provisional of U.S. provisional application No. 61/716,879 filed Oct. 22, 2013. The aforementioned application is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to a laser sighting assembly for firearms and more particularly to a laser sighting assembly with laser range finding capability having a dual mode laser operable in both a sighting mode of operation and a range-finding mode of operation. 
         [0003]    Laser sighting or targeting systems are known in the art for sighting a firearm on an intended target. Commonly, a laser sight is mounted on a firearm, such as an accessory mounting rail. When properly aligned with the barrel of the firearm, the laser will direct a beam to the target, which will appear as a dot on the target where the bullet will strike when the gun is fired. 
         [0004]    The wavelength of the sighting laser may be in the visible region, typically red or green, e.g., for use in daylight conditions. Under nighttime or other low light conditions when a night vision system is used, an infrared (IR) sighting laser may be employed having a laser that emits a beam in the infrared region to which the night vision system is sensitive. For example, a sighting laser in the near-infrared region (NIR) (e.g., about 750-1400 nanometers, typically about 800-900 nm) would be viewable to a user wearing a conventional night vision system employing image intensifier (I 2 ) technology. 
         [0005]    Likewise, thermal imaging systems are known which are sensitive to the thermal infrared region, such as medium-wave infrared (MWIR) (e.g., 3,000-8,000 nm) or long-wave infrared (LWIR) (e.g., 8,000-15,000 nm). Thermal imaging technology has also been combined with conventional night vision technology. For example, enhanced vision systems (e.g., enhanced night vision goggles or ENVGs) are known which sense both NIR and thermal IR. A sighting laser in either the NIR region would be viewable by opposing forces equipped with either conventional night vision systems or with enhanced night vision systems. 
         [0006]    Laser range finding devices are known which provide an accurate measurement of the distance to a target. In such units, a laser sends a beam toward a target and reflections of the beam from the target are detected by an optical receiver. The distance to the target is calculated based on the time-of-flight of the laser beam. The range finder typically emits a laser beam in a very short series of pulses, which may be encoded to assist the detector in recognizing the reflected signal. 
         [0007]    Integrated systems that combine a laser sight (i.e., an aiming or pointing laser) and an optical range finder system are also known. Typically, such combined systems employ one or more separate lasers for sighting and a dedicated laser for range finding. For example, a combined laser sight may employ a sighting module having an infrared laser in the NIR region so as to be visible to persons using a night vision system based image intensifier technology (e.g., night vision goggles), and a range finding module using a dedicated laser in the short-wave infrared (SWIR) region rendering it invisible to the human eye, diurnal vision systems, as well as to night vision goggles and thermal (MWIR and LWIR) cameras or imagers. In this manner, such a system having separate sighting and range finding lasers are capable of remaining covert both to the human eye and to enemies having image intensifier and/or thermal imaging systems when used for range finding. 
         [0008]    Prior art systems have not heretofore provided a laser sighting and range finding unit having single, dual function sighting and range finding laser for a number of reasons. First, it is preferable to employ a laser that is not detectable by conventional night vision or thermal imaging technology so that the range finding emissions do not inadvertently disclose the user&#39;s position to enemies. Second, the sighting laser is typically operated to produce a continuous beam, whereas the range finding laser is operated to provide a very brief pulse or series of pulses. 
         [0009]    It is, therefore, the object of the present disclosure to provide an improved laser sighting and range finding unit which eliminates the need for a dedicated IR sighting laser and a separate, dedicated range finding laser, while remaining invisible to night vision and thermal imaging technology. By providing a single, dual-purpose IR laser, the cost and size of the unit may be reduced over comparable systems using separate sighting and range finding lasers. 
       SUMMARY 
       [0010]    In one aspect, a combined range finding and sighting apparatus for a weapon includes a housing therein supporting one or more laser emitters, an optical detector for detecting an optical signal reflected from the target, and a processor. The one or more laser emitters includes a first laser emitter operable in a first mode for emitting an optical signal toward the target a second mode for projecting a first beam onto the target. The processor is coupled to a computer readable memory encoded with executable instructions and is configured, upon execution of the executable instructions, to calculate a distance to the target based on a time of flight of the optical signal. 
         [0011]    In a more limited aspect, the first beam is substantially in alignment with a trajectory of a projectile fired from the weapon. 
         [0012]    In another more limited aspect, the first laser emitter is a short wave infrared (SWIR) laser emitter. 
         [0013]    In yet another more limited aspect, the first laser emitter is configured to emit electromagnetic radiation having a wavelength that is invisible to one or both of a human eye and a night vision device employing an image intensifier. 
         [0014]    In still another more limited aspect, the first laser emitter is configured to emit electromagnetic radiation having a wavelength in the range of from about 1400 nm to about 3000 nm. 
         [0015]    In another more limited aspect, the wavelength is approximately 1550 nm. 
         [0016]    In yet another more limited aspect, the first laser emitter is configured to emit electromagnetic radiation having a wavelength that is visible to a night vision system employing a short wave infrared imaging system. 
         [0017]    In a further more limited aspect, the short wave infrared imaging system is of the type having an indium gallium arsenide (InGaAs) sensor. 
         [0018]    In still another more limited aspect, the apparatus further comprises a first actuator switch on the housing configured to actuate the first laser emitter in the first mode of operation, and, a second actuator switch on the housing configured to actuate the first laser emitter in the second mode of operation. 
         [0019]    In yet another more limited aspect, the apparatus includes a first actuator switch on the housing configured to actuate the first laser emitter in the first mode of operation. A second laser emitter is supported within the housing and configured to project a second beam substantially in alignment with a trajectory of a projectile fired from the weapon. A selector is provided for selecting one of the first laser emitter and the second laser emitter. A second actuator switch is provided on the housing configured to actuate the selected one of the first laser emitter in the second mode of operation and the second laser emitter. 
         [0020]    In yet a further more limited aspect, the apparatus further includes a second laser emitter supported within the housing and configured to project a second beam substantially in alignment with a trajectory of a projectile fired from the weapon. 
         [0021]    In another more limited aspect, the second laser emitter is selected from a visible laser emitter and an infrared laser emitter. 
         [0022]    In still another more limited aspect, the second laser emitter is a near-infrared laser emitter. 
         [0023]    In another further limited aspect, the apparatus comprises a third laser emitter supported within the housing and configured to project a third beam substantially in alignment with a trajectory of a projectile fired from the weapon, wherein the second laser emitter is an infrared laser emitter and the third laser emitter is a visible laser emitter. 
         [0024]    In yet another more limited aspect, the apparatus includes a first actuator switch on the housing configured to actuate the first laser emitter in the first mode of operation. A selector is provided for selecting one of the first laser emitter, the second laser emitter, and the third laser emitter. A second actuator switch is provided on the housing configured to actuate the selected one of the first laser emitter in the second mode of operation, the second laser emitter, and the third laser emitter. 
         [0025]    In yet another more limited aspect, the apparatus further includes an illuminator supported within the housing, the illuminator including a light emitting element for illuminating the target. 
         [0026]    In yet another more limited aspect, the light emitting element is a fourth laser emitter. 
         [0027]    In yet another more limited aspect, the fourth laser emitter is an IR laser emitter. 
         [0028]    In another more limited aspect, the apparatus further comprises adjustable optics for adjusting a beam angle of light emitted by the illuminator. 
         [0029]    In yet another more limited aspect, the apparatus further includes a first actuator switch on the housing configured to actuate the first laser emitter in the first mode of operation. A selector is provided for selecting one of the first laser emitter, the second laser emitter, the second laser emitter in combination with the illuminator, and the third laser emitter. A second actuator switch on the housing configured to actuate the selected one of the first laser emitter in the second mode of operation, the second laser emitter, the second laser emitter in combination with the illuminator, and the third laser emitter. 
         [0030]    In still another more limited aspect, the selector further includes a “range” selection, wherein the second actuator switch is disabled when the selector is in the “range” selection. 
         [0031]    In another more limited aspect, the selector is a rotary switch. 
         [0032]    In yet another more limited aspect, the apparatus further includes a human viewable display and the selector is a user operable display screen interface displayed on the human viewable display. 
         [0033]    In still another more limited aspect, the apparatus further comprises an illuminator supported within the housing, the illuminator including a light emitting element for illuminating the target. 
         [0034]    In yet another more limited aspect, the apparatus further comprises a fastener for attaching the apparatus to a firearm. 
         [0035]    In still another more limited aspect, the fastener is a clamping member configured to attach to a firearm rail interface. 
         [0036]    In yet another more limited aspect, the apparatus further comprises one or more mechanical sights on the housing. 
         [0037]    In another more limited aspect, the optical signal has a duration in the range of about 10 milliseconds to about 1000 milliseconds. 
         [0038]    In yet another more limited aspect, the optical signal comprises a plurality of optical pulses. 
         [0039]    In yet another more limited aspect, the first beam is selected from a continuous beam and a pulsed beam having a pulse frequency that is sufficiently high to allow the pulsed beam to appear as a substantially continuous beam. 
         [0040]    In yet another more limited aspect, the pulsed beam has a pulse frequency in the range of about 5 Hertz to about 60 Hertz. 
         [0041]    In still another more limited aspect, the apparatus further comprises a display for displaying a numerical indication of the distance to the target. 
         [0042]    In another more limited aspect, the numerical indication of the distance to the selected target is selected from one or both of an actual distance to the selected target and an effective ballistic distance to the selected target. 
         [0043]    In yet another more limited aspect, the apparatus further includes a power supply supported within the housing. 
         [0044]    In yet another more limited aspect, the apparatus further includes a first adjustment means for changing an alignment of the apparatus to effect windage changes in a trajectory of a laser beam generated by the first laser emitter. A second adjustment is also provided for changing the alignment of the apparatus to effect elevation changes in the trajectory of a laser beam generated by the first laser emitter. 
         [0045]    In still another more limited aspect, the one or more laser emitters are removably supported in the housing. 
         [0046]    In yet another more limited aspect, the apparatus further includes a laser module removably supported in the housing. The laser module including the first laser emitter and at least one additional laser emitter, wherein each of the at least one additional laser emitter is affixed in co-aligned relation with the first laser emitter. 
         [0047]    In another aspect, a method of using a combined range finding and sighting apparatus includes supporting one or more laser emitters, an optical detector, and a processor within a housing. The processor is coupled to a computer readable memory encoded with executable instructions. A first one of the one or more laser emitters is activated in a first mode to emit an optical signal toward a target. The optical signal reflected from the target is detected with the optical detector. The processor executes the executable instructions to calculate a distance to the target based on a time of flight of the optical signal. The first laser emitter is activated in a second mode to project a first beam onto the target. 
         [0048]    In another more limited aspect, the method further includes mounting the combined range finding and sighting apparatus to a weapon, wherein the first beam is projected substantially in alignment with a trajectory of a projectile fired from a weapon. 
         [0049]    In yet another more limited aspect, the method herein further includes outputting the calculated distance to a human viewable display. 
         [0050]    In still another more limited aspect, the first laser emitter emits electromagnetic radiation having a wavelength that is invisible to one or both of a human eye and a night vision device employing an image intensifier. 
         [0051]    In further more limited aspect, the first laser emitter emits electromagnetic radiation having a wavelength in the range of from about 1400 nm to about 3000 nm. 
         [0052]    In yet another more limited aspect, the wavelength is approximately 1550 nm. 
         [0053]    In still another more limited aspect, the first laser emitter emits electromagnetic radiation having a wavelength that is visible to a night vision system employing a short wave infrared imaging system. 
         [0054]    In another more limited aspect, the short wave infrared imaging system is of the type having an indium gallium arsenide (InGaAs) sensor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0055]    The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention. 
           [0056]      FIG. 1  is an isometric view, taken generally from the rear, of a combined laser sighting and range finding assembly with dual function IR laser in accordance with a first exemplary embodiment of the present invention. 
           [0057]      FIG. 2  is an enlarged, fragmentary view of the apparatus appearing in  FIG. 1 . 
           [0058]      FIG. 3  is an isometric view of the unit appearing in  FIG. 1  with the housing cover and auxiliary laser assemblies removed, illustrating the dual mode SWIR laser and optical receiver modules. 
           [0059]      FIG. 4  is an isometric view similar to the view appearing in  FIG. 3 , also showing the visible laser and the first and second IR lasers. 
           [0060]      FIG. 5  illustrates an optional laser safety key provided to prevent inadvertent or unauthorized changes to the laser output power level. 
           [0061]      FIG. 6  is a functional block diagram illustrating the architecture of the  FIG. 1  embodiment. 
           [0062]      FIG. 7  is a flow diagram illustrating an exemplary laser power adjustment method. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0063]    Referring to the drawings,  FIGS. 1-6  illustrate an exemplary combined laser sighting and range finding apparatus  100  which includes a SWIR laser module or assembly  110  and an optical receiver module or assembly  120 . The SWIR laser module  110  includes a laser  112  driven by laser driver electronics  132  under the control of a processor  134 , such as a microprocessor, microcontroller, or the like. The components of the unit  100  are received within a housing  102 . One or more switches, selectors, keypad buttons, or the like are provided for accessing the various functions of the unit  100 , designated generally as input/output (I/O) circuitry  140 , as described below in connection with the illustrated exemplary embodiment. 
         [0064]    A SWIR laser signal  116  emitted by the laser  112  passes through optics  114 , which may comprise a lens or lens array  114  and which may include other optical elements, including reflective optical elements, refractive optical elements, or combinations for focusing and/or directing the beam  116  toward a target The laser beam  116  may have a wavelength which is in the short-wave IR region or sufficiently near the short-wave IR region so as to be visible to night vision systems employing a SWIR imaging system, such as a SWIR camera of the type having an indium gallium arsenide (InGaAs) sensor. Preferably, the laser  112  emits a beam having a wavelength in the range of from about 1400 nm to about 3000 nm, more preferably about 1550 nm. 
         [0065]    In operation, to use the unit  100  for range finding, the unit is pointed at a target to be ranged. For example, in the illustrated embodiment which is especially adapted for weapon-mounted use, the user may aim the weapon at the target using a weapon-mounted scope or sight that has been co-aligned with the unit  100 . Alternately, an integral sight comprising front and rear mechanical sights  226 ,  228  on the housing  102  may also be employed. When the unit  100  is aimed at the target, the range select button  142  is pressed, which actuates the SWIR laser  112  in a range finding mode. In preferred embodiments, actuation of the range select button  142  is operable to activate the SWIR laser  112 , irrespective of the position of mode selector switch  146  (with the exception of the “off” and “function” positions, in which cases operation of the lasers are disabled. 
         [0066]    The beam  116 , when actuated in the range finding mode, is a very short duration, e.g., in the range of about 10 milliseconds to about 1000 milliseconds. The beam  116  is emitted and focused by the lens array  114 , and reflected from the target as a reflected beam  126 , which is received by the optical receiver  120 . The reflected beam  126  passes through optics  124  such as a lens or an array of lenses of the receiver  120 , and which may include other optical components, to direct the reflected beam  126  to a photosensor  128 , such as a camera, photodetector, etc. 
         [0067]    The microprocessor  134  calculates the time period between the emission of the emitted beam  116  by the laser  112  and the detection of the reflected beam  126  by the sensor  128 . The calculated distance to the target may be output in human viewable form to a display  136 . The distance to the target may be used by the operator, for example, to determine whether the target is within the range of a given weapon or to allow the user to adjust his or her aim to account for range, e.g., to compensate for ballistic drop of the bullet or other fired projectile. The calculated range could also be communicated to an optical scope, sight, weapon video display, or the like, to displace a reticle or dot so that it appears at the point of impact based on a ballistics computation. The calculated range could also be fed to a fire control system or another weapon system. 
         [0068]    To access the second, pointing or sighting mode of operation, the selector switch  146  is rotated until it points to a desired laser (or lasers) to user for sighting/pointing and the laser button  144  is pressed. It will be recognized that the button  144  may operate in a variety of manners. For example, the button  144  could operate as a simple toggle, wherein the selected pointing laser operates in a steady on mode when the button  144  is pressed for first time and turned off when the button  144  is pressed a second time. Other options are also contemplated. For example, in an alternative embodiment, the selected laser is turned on while the button  144  is pressed and turned off when the button  144  is released. In still further embodiments, on and off functions can be accessed by button press combinations the selected laser is turned on while the button  144  is pressed and turned off when the button  144  is released. For example, in a still further embodiment, laser can turned on while the button  144  is pressed and turned off when the button  144  is released, but can be turned on and remain on following a double tap of the button  144 , i.e., by pressing the button twice in rapid succession. In another option, the steady on condition may be achieved by holding the button  144  down for some predetermined period of time, e.g., several seconds. In still further embodiments, the multiple button behaviors may be provided, and which can be selected by the user via the FUNCTION menu hierarchy. 
         [0069]    In the illustrated embodiment of  FIG. 1 , the selector knob  146 , includes an indicator element  148  and can be rotated until it is aligned with a desired one of multiple positions, including an “OFF” position  152 , “RANGE” position  154 , “IR LASER” position  156 , “IR DUAL” position  158 , “FUNCTION” position  162 , “SWIR” position  164 , and “VIS LASER” position  166 . 
         [0070]    When the knob  146  is in the “OFF” position  152 , the unit is powered down. When the knob  146  is in the “RANGE” position  154 , the range button  142  is operable to actuate the SWIR laser  112 . In the preferred embodiment, all laser pointing or sighting functions are disabled when the selector  146  is in the “RANGE” position  154 . 
         [0071]    When the knob  146  is in the “IR LASER” position  156 , the button  144  is operable to actuate a first IR laser module or assembly  170  including a first IR laser  172  and associated optics  174 . The button  144  can be actuated in this mode to emit an IR beam  176  for sighting/pointing, e.g., by placing an IR dot on a target. The beam  176  is preferably in the NIR region and visible to persons utilizing night or low light vision systems employing image intensifier technology, such as night vision goggles or enhanced night vision goggles. When the knob  146  is in the “IR LASER” position  156 , the SWIR laser module  110  may still be actuated in range finding mode when the button  142  is pressed. 
         [0072]    When the knob  146  is in the “IR DUAL” position  158 , the button  144  is operable to simultaneously actuate the first, sighting IR laser  172  as discussed above, as well as a second IR laser module  180 , including a second IR laser  182  and associated optics  184 . The second IR laser module  180  functions as an IR illuminator or flashlight. When the button  144  is actuated in the DUAL IR mode the second IR laser  182  is actuated to emit a beam  186  for illuminating a target area and further wherein the sighting beam  176  appears as a dot centered in the illuminated area. A rotatable adjustment wheel  106  is provided to allow the divergence of the illumination beam  186  to be adjusted to a desired beam angle, e.g., by controlling the optics  184 . For example, the beam angle may range from a relatively wide-angle flood beam, e.g., about 10 degrees or greater, to a focused spot. The IR illumination beam  186  is preferably in the NIR region and visible to persons utilizing night or low light vision systems employing image intensifier technology. When the knob  146  is in the “DUAL IR” position  158 , the SWIR laser may still be actuated in range finding mode when the button  142  is pressed. 
         [0073]    When the knob  146  is in the “SWIR” position  164 , the button  144  is operable to actuate the laser  112  in the aiming/sighting/pointing mode, such that the emitted beam  116  is visible using a SWIR vision system. The SWIR spot can be placed on an intended target, e.g., to show the intended point of impact, or to designate a target for attack by other personnel or another weapon system. 
         [0074]    Unlike prior art systems, the dual-purpose laser  112  herein is also employed as a pointing laser. Lasers employed in prior art laser range finders normally employ high power monoblock crystal lasers which are operated to emit short, high power laser pulses. Furthermore, the pulses in such prior art laser range finders must be time spaced in order to achieve sufficient peak power and are not capable of a pulse repetition rate that would allow the pulse train to appear as a substantially continuous beam. In contrast, the present system employs a SWIR laser, which may be a laser diode, operable in the pointing mode to emit a beam at a pulse repetition rate that is sufficiently high to allow the pulsed beam to appear as a substantially continuous beam 
         [0075]    In the aiming mode of operation of the presently disclosed system, the laser  112  may be a SWIR laser diode and the SWIR beam  116  is emitted as a pulsed beam to avoid excessive heating of the laser  112 . The pulses may be emitted for a duration and at a frequency such that the beam  112  appears as a substantially continuous beam to a user donning a SWIR vision system. The pulse frequency may be in the range of from about 5 Hz to about 60 Hz, and is preferably in the range of from about 10 Hz to about 25 Hz. In this manner, a laser dot can be seen on the target by a user with a SWIR vision system, while remaining invisible the naked eye as well as to conventional night vision and/or thermal imaging systems, thus providing a more covert aiming or sighting beam. As used herein, the term “appears as a substantially continuous beam” is intended to encompass a pulsed beam wherein the frequency and laser-on time is sufficient to be human perceptible to a user wearing a SWIR-sensitive vision system, and is not intended to preclude some perceptible fluctuations in intensity as a result of the pulsed nature of the beam, nor is it intended to preclude operating the laser  112  to provide a flashing beam  116  which alternates between periods of time much longer than the time between pulses during which the beam appears as a substantially continuous beam, followed by periods of time in which the laser is off, such that a blinking or flashing effect is created. 
         [0076]    In preferred embodiments, when the knob  146  is in the “SWIR” position  164 , the SWIR laser may still be actuated in range finding mode by pressing the button  142 . In certain embodiments, if the SWIR is being operated in aiming/pointing mode when the range button  142  is pressed, the SWIR laser is momentarily switched from aiming mode to range finding mode to emit a range finding beam and then automatically resumes operation in aiming mode once the range finding pulse has been emitted. In other embodiments if the SWIR is being operated in aiming/pointing mode when the range button  142  is pressed, the SWIR laser switches from aiming mode to range finding mode and is then shut off. 
         [0077]    When the knob  146  is in the “VIS LASER” position  166 , the button  144  is operable to actuate a visible laser module or assembly  190  including a visible laser  192  and associated optics  194 . The button  144  can be actuated in this mode to emit a visible (e.g., red or green) beam  196  for sighting/pointing, e.g., by placing a visible laser dot on a target, visible to the naked eye or diurnal vision systems. When the knob  146  is in the “VIS LASER” position  166 , the SWIR laser may still be actuated in range finding mode when the button  142  is pressed. 
         [0078]    When the knob  146  is in the “FUNCTION” position  162 , the lasers  112 ,  174 ,  184 , and  194  cannot be actuated. The buttons  142 ,  144 ,  168 , may be used to access various programmable features of the unit  100 , such as laser power or intensity or other user preference settings, and so forth. For example, in certain embodiments, when in the FUNCTION mode, the buttons  142 ,  144 ,  168  could be used to select a desired intensity, for example, to toggle between high and low intensity (e.g., to reduce the laser power output to a so-called or designated “eye safe” levels), or, alternatively, to select a desired intensity from within a range of intensities. 
         [0079]    Although the selector  146  has been described as a manually rotatable knob in the depicted preferred embodiment, it will be recognized that the manual mode selection knob  146  could be replaced with a user operable on-screen interface, such as a menu-driven hierarchy navigated via the display  136  using buttons, a keypad, touch pad, touch screen, joy stick, etc. 
         [0080]    In certain embodiments, a remote trigger port  147  may be provided to access various functions and actuate the unit  100  via a remote control unit connected to the port  147 . 
         [0081]    In certain embodiments, the laser output power of the one or more of the laser units ( 112 ,  172 ,  182 ,  192 ) is adjustable. A low power eye safe mode is useful, for example, in preventing eye damage when using the unit  100  during training exercises. 
         [0082]    In certain embodiments where adjustable laser output is provided, the laser output power is set to a desired level at the factory, e.g., to operate in either a low power (e.g., eye safe) mode or high power laser mode, but is not otherwise adjustable by the end user. 
         [0083]    In other embodiments where adjustable laser output is provided, the laser output power can be toggled between a low power mode and a high powered mode. In some embodiments, the laser power level toggle function can be accessed using the buttons on the unit  100 , e.g., via a function menu appearing on the display screen  136 . preferably, onscreen indicia may be provided designating the selected laser power output level. 
         [0084]    In preferred embodiments, an adjustable laser power level is provided, wherein adjustment of the laser power level requires a laser safety key  198  as shown in  FIG. 5 . In the illustrated embodiment, the laser safety key  198  is plugged into the remote trigger connection port  147 , although it will be recognized that a dedicated laser safety key port could also be provided. 
         [0085]    In embodiments employing a laser safety key, when it is desired to change the power mode, the laser safety key  198  is inserted into the remote trigger connection port  147 . In a preferred embodiment, when the laser safety key  198  is not plugged into the port  147 , only the current laser power mode will be available, e.g., when accessing a laser power selection menu displayed on the display screen when navigating an on-screen function menu hierarchy using the buttons. In this manner, personnel are prevented from accidentally switching from a low (e.g., eye safe) power mode to a high (e.g., eye damaging) power mode when in training and likewise accidentally switching from a low (e.g., eye safe) power mode to a high (e.g., eye damaging) power mode when operating in the field. 
         [0086]    It is contemplated that in some instances, the key could be issued to the end user, who could set the unit to a desired laser power level and remove the key to prevent the possibility that the laser output mode would be changed until the key is reinserted. In other instances, it is contemplated that access to the key can be limited to certain supervisory personnel, who would use the key to set the desired laser power level prior to issuing the units to the end users to thereby restrict the end user&#39;s ability to alter the power level. 
         [0087]    In some embodiments, the key  198  unlocks power level selection options, thereby enabling the user to navigate the menu hierarchy via the display screen and input buttons. Alternatively or additionally, in certain embodiments, when it is desired to change the power output mode, the key  198  is inserted into the connection port  147  and the unit  100  is activated. When the unit  100  is activated while the key  198  is present in to port  147 , the output power to toggle between low power output and high power output or vice versa. An indication of the new power setting is preferably output to the LED display. Powering the unit off by rotating the knob  146  to the off position  152  and removing the laser safety key  147  from the connection port  198  will cause the unit  100  to remain at the currently selected power level until it is changed again with the safety key. 
         [0088]    Preferably, when the power level is set to high power mode, all lasers will operate in the high power (e.g., non eye-safe) mode and when the power level is set to the low power mode, all lasers will activate at low power (e.g., eye safe) mode. However, in other embodiments, individual adjustment of the laser power output is also contemplated. 
         [0089]    In certain embodiments, setting the laser power output to the high power mode may cause the laser output to be set to some predetermined or fixed high power level and setting the laser power output to the low power mode may cause the laser output to be set to some predetermined or fixed low or eye-safe power level. 
         [0090]    In other embodiments, there is provided a range of selectable laser power levels. The number of levels may be, for example, from 5 to 10, and preferably about 8. When a range of laser power levels is provided, the toggle function between high and lower power modes functions to limit the maximum laser power output level. For example, when the high power mode is selected, the full range of laser power output levels are available, but when the low power mode, only levels that do not exceed some preselected power level (e.g., a level which is eye-safe) are available. 
         [0091]    In certain embodiments, the laser power output level is adjusted using the input buttons to navigate the menu hierarchy, e.g., when the knob  146  is in the function position  162 . In preferred embodiments, the laser power level is adjustable when in a pointing and/or illumination mode, an exemplary implementation of which is described below. 
         [0092]    A flow chart illustrating an exemplary manner of adjusting the laser power output level when in a pointing or illumination mode, i.e., “on the fly,” appears in  FIG. 7 . An advantage of allowing intensity adjustments to be made during activation of the laser is that the user can visualize the laser (using appropriate viewing devices for the IR and SWIR lasers) to assist in setting a desired level. 
         [0093]    In operation, the unit is placed in one of the one of the SWIR, visible, or infrared modes (step  700 ) and the selected laser (or lasers when Dual IR is selected) is activated using the button  144  (step  702 ). At step  704 , the state of the button  168  is monitored. If button  168  is pressed, the process proceeds to step  706  and the current adjustment mode is displayed. If the button  168  is pressed at step  704 , pressing the buttons  144  (step  708 ) and  142  (step  710 ) function to incrementally increase (step  712 ) and decrease (step  714 ), respectively, the laser power output level. 
         [0094]    In exemplary embodiments, if the unit  100  is set to a low power mode, the buttons  144  and  142  allow the user to increment or decrement the laser power level only within the low or eye safe power range, e.g., powers “0” through “3.” Likewise, if the unit  100  is set to a high power mode, pressing the buttons  144  (step  708 ) and  142  allow the user to increment or decrement the laser power level within the full power range, e.g., powers “0” through “7”. It will be recognized that other numbers of incremental steps are possible. 
         [0095]    Once the desired laser intensity level has been selected with the buttons  144  and  142 , pressing the butting  168  (step  716 ) will save the changes to memory and exit the power adjust mode (step  720 ), such that the saved power level will be used for subsequent actuations of the adjusted laser. In certain embodiments, the unit  100  proceeds to step  720  and saves the changes automatically and exits after a predetermined period of inactivity (step  718 ) has occurred, e.g., if the engage button  168  is not pressed after some predetermined period of time, such as 5 seconds. 
         [0096]    In the preferred embodiments, the selection between the low (e.g., eye-safe) and high (e.g., eye damaging) modes will apply globally to all lasers, while the selection of a power level within the selected mode using the buttons  142 ,  144 , and  168  will be saved for each laser individually. 
         [0097]    With reference to  FIGS. 1-6 , the electronic components of the unit  100 , including the lasers and the laser electronics  132 , the microprocessor  134 , the display  136 , the sensor  128 , and so forth, are powered by an internal power supply  138  such as a battery or a battery pack, received within a compartment in the housing  102  and accessible via a cover  108 . In certain embodiments, the power supply may also be used to power an attached accessory electrically coupled to the unit  100 . In alternative embodiments, the unit  100  may be powered by an external power supply, such as a power supply of an electrically coupled accessory or a remote power supply. For example, power may be supplied to the unit over a powered accessory mounting rail. 
         [0098]    The illustrated unit  100  is adapted for attachment to a weapon rail interface, such as a Picatinny rail interface. In the illustrated preferred embodiment, the unit  100  includes a channel  210  receiving a weapon rail interface (not shown) and threaded fastener  212  which removably engages a complimentary threaded hole in the rail interface, avoiding the need for a rail clamp. For example, the fastener  212  may be ¼″- 20  bolt engaging a tapped ¼″- 20  hole on the mounting rail. Alternatively, a rail clamp or rail grabber may be employed to mechanically secure the unit  100  to a firearm. 
         [0099]    A first adjustment screw  214  is provided for elevation adjustment for alignment of the laser module  180  and a second adjustment screw  216  is provided to provide an azimuth or windage adjustment of the laser module  180 . The laser modules  110 ,  170 , and  190  may each have similar elevation and azimuth adjustment screws. The elevation and azimuth of the four laser modules may thus be co-aligned to within some predetermined accuracy relative to each other on the internal frame of chassis  220  prior to final assembly. For example, the four lasers can be co-aligned to each focus a beam within +/−0.5 mm at 25 meters. Once the laser modules are co-aligned with respect to each other, they may be affixed in a substantially permanent manner, for example with an epoxy or other adhesive. 
         [0100]    One advantage of the depicted preferred embodiment herein resides in the use of separate a visible laser module, SWIR laser module, IR aiming laser module, and IR illumination module, such that the unit  100  can be repaired in the event one of more of the laser modules  110 ,  170 ,  180 , and  190 , or any other replaceable assembly within the unit  100  (e.g., the optical receiver module  120 , main circuit board  218 , etc.), becomes defective. By employing removable and replaceable components, the unit  100  can be repaired should one component or assembly malfunction, unlike many prior art laser range finder and sighting devices. Thus, the substantially permanent attachment of the laser in their fixed, co-aligned positions with a substantially permanent adhesive such as epoxy, as detailed above, does not preclude later removal of the substantially permanent adhesive, for example through the application heat to melt the cured epoxy or other adhesive, e.g., for the purpose of removing and replacing a defective module. In preferred embodiments, the housing  102  can be formed in separate sections, e.g., separate fore and aft case sections, wherein the each of the housing shell sections are individually replaceable. 
         [0101]    Once the lasers are co-aligned relative to one another and the unit  100  is assembled, an elevation adjustment  222  and an azimuth adjustment  224  may be used to adjust the alignment of the unit  100  as a whole relative to a weapon, e.g., to boresight the unit  100  to the bore of the weapon and/or any other scopes or sights on the weapon. Although a weapon-mounted unit  100  is disclosed herein, it will be appreciated that other configurations are also contemplated. For example, the unit  100  as shown could also be removed from a weapon and used as a hand held unit. In certain other embodiments, a unit designed for handheld use only is also contemplated. In still other embodiments, a unit as described herein could be integrated as a built in or stock feature on a firearm. 
         [0102]    The invention has been described with reference to the preferred embodiments. Modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as encompassing all such modifications and alterations.