Patent Publication Number: US-2010110198-A1

Title: Mid infrared optical illuminator assembly

Description:
RELATED INVENTION 
     This application claims priority on U.S. Provisional Application Ser. No. 61/041,541, filed Apr. 1, 2008 and entitled “OPTICAL ILLUMINATOR ASSEMBLY”. As far as is permitted, the contents of U.S. Provisional Application Ser. No. 61/041,541 are incorporated herein by reference. 
    
    
     BACKGROUND 
     People operating an aircraft, sea vessel, military vehicles or other types of vehicles, need to be able to see in inclement conditions, such as fog, rain, snow, smoke, or dust. For example, it is well know that pilots have difficulty locating a runway in foggy conditions. 
     Further, emergency workers, sportsmen, and military people often need to see in inclement conditions. For example, a soldier will have difficulty targeting an enemy combatant in the foggy conditions, and smoke can significantly influence the ability of a fireman to see. 
     SUMMARY 
     The present invention is directed to an optical illuminator assembly for locating an object. In one embodiment, the optical illuminator assembly includes a MIR laser source having a semiconductor laser that directly emits (without frequency conversion) an output beam that is in the MIR range, the output beam being useful for locating the object. Additionally, the optical illuminator assembly can include a MIR imager that captures an image of light in the MIR range near the object. Further, the MIR imager includes an image display that displays the captured image. 
     With this design, the optical illuminator assembly is useful for locating and/or seeing an object in inclement conditions, such as fog, rain, snow, smoke, clouds, or dust in the atmosphere. There are a number of different usages for the optical illuminator assembly. In a first example, the MIR laser source and the MIR imager are spaced apart, and the image captured by the MIR imager includes the output beam from the MIR laser source. With this design, a person operating a vehicle will be able to locate the object by locating the output beams in inclement conditions. Alternatively, in a second example, the MIR laser source and the MIR imager are positioned in close proximity to each other. In the second example, the image captured by the MIR imager includes at least a portion of the object illuminated by the output beam from the MIR laser source. With this design, emergency workers, vehicle operators hikers, sportsmen, or military people will be better equipped to locate the object in inclement conditions. 
     In either case, the MIR laser source illuminates the area near the object and significantly improves the image captured by the MIR imager. As a result thereof, the optical illuminator assembly can be used to quickly and accurately locate the object. 
     Further, in certain embodiments, because of the unique design disclosed herein, the optical illuminator assembly is very accurate and can be extremely lightweight, stable, rugged, small, self-contained, and portable. 
     As used herein, to be classified as a MIR laser source, the output beam of the MIR laser source has a wavelength in the range of approximately 2-20 microns. Stated in another fashion, as used herein, the MIR range is approximately 2-20 microns. 
     In one embodiment, the present invention is directed to a combination that includes the optical illuminator assembly, and a vehicle that transports a person. In this embodiment, the image display is viewable to the person being transported by the vehicle. This feature allows the person to “see” through inclement conditions. Further, in this example, the optical illuminator assembly can be secured to the vehicle or incorporated into a pair of goggles worn by the person. 
     In another embodiment, the combination includes the optical illuminator assembly, and a gun. In this embodiment, the MIR laser source is secured to the gun, and the image display is viewable to a person using the gun. With this design, the optical illuminator assembly allows a soldier to “see” their target through inclement conditions. 
     In yet another embodiment, the combination includes an object, and a plurality of spaced apart MIR laser sources that are positioned near the object. With this design, the MIR imager can be used to locate the object in inclement conditions. For example, the object can be an airport runway, and the plurality of spaced apart MIR laser sources can be positioned near the airport runway. With this design, an MIR imager positioned on an airplane can be used to locate the airport runway in inclement conditions. In another example, the object can be a harbor inlet, and one, or a plurality of spaced apart MIR laser sources can be positioned near the harbor inlet. With this design, an MIR imager positioned on a boat can be used to locate the harbor inlet in inclement conditions. 
     In certain embodiments, the MIR laser source includes a mounting base, a QC gain media that is fixedly secured to the mounting base, a cavity optical assembly that is fixedly secured to the mounting base spaced apart from the QC gain media, and a WD feedback assembly that is secured to the mounting base spaced apart from the QC gain media. In certain embodiments, the WD feedback assembly cooperates with the QC gain media to form an external cavity that lases within the MIR range. In certain embodiments, the QC gain media contains a high reflective (HR) coating on one or both facets. 
     Additionally, power can be directed to the QC gain media in a pulsed fashion to reduce power consumption. This allows the MIR laser source to be sufficiently powered by a battery for a longer period of time than when used in a continuous wave (CW) mode of operation. With this design, the imaging system is very portable. Alternatively, the MIR laser source can be in a CW mode of operation. 
     Further, the imaging system can include a temperature controller that is in thermal communication with the mounting base. In this embodiment, the temperature controller controls the temperature of the mounting base and the QC gain media. As a result of the integrated temperature controller, the illuminator assembly can be used in remote locations away from external cooling sources. In certain embodiments, the temperature controller is required to ensure a constant optical output power for consistent operation. In these embodiments, the internal temperature control allows for consistent operation in remote locations. In an alternative embodiment, the illuminator assembly can be operated without active temperature control. 
     The present invention is also directed to one or more methods for locating an object in inclement conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
         FIG. 1  is simplified illustration of a vehicle, an object, and one embodiment of an optical illuminator assembly having features of the present invention; 
         FIG. 2A  is simplified side illustration, in partial cut-away of a MIR laser source having features of the present invention; 
         FIG. 2B  is a simplified side illustration of another embodiment of a MIR laser source having features of the present invention; 
         FIG. 2C  is a simplified side illustration of another embodiment of another MIR laser source having features of the present invention; 
         FIG. 2D  is a simplified side illustration of yet another embodiment of another MIR laser source having features of the present invention; 
         FIG. 3  is a graph that illustrates one embodiment of a power profile directed to the MIR laser source of  FIG. 2 ; 
         FIG. 4A  is a simplified side illustration of a MIR imager having features of the present invention; 
         FIG. 4B  is a simplified side illustration of another embodiment of a MIR imager having features of the present invention; 
         FIG. 5  is simplified illustration of another vehicle, an object, and the optical illuminator assembly; 
         FIG. 6  is simplified illustration of another vehicle, an object, and another embodiment of the optical illuminator assembly; 
         FIG. 7  is simplified top illustration of another vehicle, an object, and another embodiment of the optical illuminator assembly; 
         FIG. 8  is simplified side illustration of another vehicle, an object, and yet another embodiment of the optical illuminator assembly; 
         FIG. 9  is simplified side illustration of another vehicle, an object, and still another embodiment of the optical illuminator assembly; 
         FIG. 10  is simplified side illustration of a person, an object, and another embodiment of the optical illuminator assembly; 
         FIG. 11  is simplified side illustration of the person, an object, and another embodiment of the optical illuminator assembly; and 
         FIG. 12  is simplified side illustration of the person, an object, and yet another embodiment of the optical illuminator assembly. 
     
    
    
     DESCRIPTION 
       FIG. 1  is a simplified illustration of a combination including a first embodiment of an optical illuminator assembly  10  having features of the present invention. In this embodiment, the optical illuminator assembly  10  includes one or more MIR laser sources  12  (illustrated as a box) and a MIR imager  14  (illustrated as a box). Each MIR laser source  12  generates an output beam  16  that is in the MIR range, and the MIR imager  14  captures an image  18  (illustrated away from the MIR imager  14  for clarity) of light in the MIR range. 
     As provided herein the optical illuminator assembly  10  is useful for locating and/or seeing an object  20  in inclement conditions  22  (illustrated as small circles), such as fog, rain, snow, smoke, clouds, or dust in the atmosphere. There are a number of different usages for the optical illuminator assembly  10 , only a few of which are illustrated herein. In a first example, the MIR laser source  12  and the MIR imager  14  are spaced apart as illustrated in  FIG. 1 . In the first example, the image  18  captured by the MIR imager  14  includes the output beam  16  from the MIR laser source  12 . With this design, a person operating a vehicle  24  will be able to locate the object  20  (e.g. a destination) in inclement conditions  22 . 
     Alternatively, in a second example, the MIR laser source  12  and the MIR imager  14  are positioned in close proximity to each other as illustrated in  FIGS. 6-12 . In the second example, the image  18  captured by the MIR imager  14  includes at least a portion of the object illuminated by the output beam  16  from the MIR laser source  12 . With this design, emergency workers, hikers, sportsmen, or military people will be better equipped to locate the object  20  in inclement conditions. 
     In either case, the MIR laser source  12  illuminates the area near the object  20  and significantly improves the image  18  captured by the MIR imager  14 . As a result thereof, the optical illuminator assembly  10  can be used to quickly and accurately locate the object  20 . 
     In the embodiment illustrated in  FIG. 1 , the destination  20  is an airport runway, and the vehicle  24  is an aircraft, e.g. a plane, helicopter, or other airborne vehicle. Further, in  FIG. 1 , the optical illuminator assembly  10  includes a plurality of spaced apart MIR laser sources  12  that are positioned near the airport runway  20 , and each MIR laser source  12  generates the output beam  16  that is directed generally upward and towards the incoming air traffic. For example, the MIR laser sources  12  can partly or fully line one or both sides of the airport runway  20 , and/or near the beginning of the runway  20 , and/or near the end of the runway  20 . In this design, the output beams  16  are substantially parallel to each other. In  FIG. 1 , the MIR laser sources  12  are positioned adjacent to both sides of the airport runway  20 , at the beginning of the runway  20 , and at the end of the runway  20 . In alternatively, non-exclusive examples, the MIR laser sources  12  are positioned on or within approximately 5, 20, 40, 50, 80, 100, or 1000 feet of the runway. 
     In certain embodiments, one or more of the output beam  16  can be aligned with the approach flight path of the runway  20  to provide directional navigational assistance to an airborne vehicle  24 , guiding it safely to the runway  20 . In certain embodiments, the laser sources  12  can be used to identify a temporary runway established in an open field during civil emergencies or military combat situations. 
     It should be noted that one or more of the MIR laser sources  12  can include an actuator  12 A that can be used to move the direction of the output beam  16 . With this design, the actuator  12 A can be used to cause the direction of one or more of the output beams  16  to be changed to better assist the pilot  28  in locating the runway  20 . 
     Moreover, in certain embodiments, the MIR imager  14  is positioned within and/or is secured to the vehicle  24 . In  FIG. 1 , the MIR imager  14  is secured to the aircraft frame and the MIR imager  14  includes an imager display  26  (illustrated away from the MIR imager  14  for clarity) that is viewable by a user  28 , e.g. a pilot. In one embodiment, the MIR imager  14  is an infrared display that provides real-time, high resolution thermal images  18  that can be displayed on the imager display  26 . 
     For example, the imager display  26  can be secured to the dash of the vehicle  24  in the cockpit of the aircraft. Alternatively, the imager display  26  can be incorporated into goggles worm by the user  28 . Still alternatively, the entire MIR imager  14  can be incorporated into goggles worm by the user  28 . 
     In  FIG. 1 , the MIR imager  14  is directed downward towards the runway  20 , and the image  18  provided the MIR imager  14  includes a plurality of spots of light  30  that are positioned adjacent to the runway  20 , a set of lights  30  that mark the beginning and end of the runway, a single light  30 A that provides a glide slope for a directly approaching airborne vehicle  24 , or any combination thereof. With this design, the optical illuminator assembly  10  is useful for the pilot  28  to locate the outline of the runway  20  in inclement conditions  22 , such as inclement weather (fog, rain, snow, smoke, clouds, dust, or other situations where gases in the atmosphere have rendered it opaque at visible and other wavelengths). In this embodiment, the optical illuminator assembly  10  can be referred to as an avionic illuminator. 
     In one embodiment, the MIR imager  14  can be moved relative to the aircraft  24  by the user  28 . For example, in one embodiment, the MIR imager  14  can be moved side to side and/or up and down by the user  28  to change the area in which the MIR imager  14  is viewing. 
     The MIR laser source  12  generates the output beam  16  having a center wavelength that is within the MIR range. The design of the MIR laser source  12  can be varied according to the requirements of the optical illuminator assembly  10 . In one embodiment, the MIR laser source  12  generates the output beam  16  that is fixed at a precisely selected, specific wavelength in the MIR range. Alternatively, the laser source  12  can generate an output beam  16  that is selectively adjustable (tuned) to any specific wavelength in the MIR range. Still alternatively, the MIR laser source  12  can be designed to sequentially generate output beams  16 , with each subsequent output beam  16  having a different center wavelength than the previous output beam  16  that is within the MIR range. 
     An important aspect of the output beam  16  is the ability propagate through inclement conditions  22  (illustrated as small circles) in the atmosphere with minimal absorption. Atmospheric propagation requires an accurate settable wavelength to avoid absorption. Typically, the atmosphere is mainly water and carbon dioxide. With the present invention, the wavelength of the output beam  16  is specifically selected to avoid the wavelengths that are readily absorbed by water, carbon dioxide, or other common inclement conditions  22 . Stated in another fashion, the wavelength of the output beam  16  is selected to facilitate maximum transmission through the inclement conditions  22 . 
     In certain embodiments, the output beam  16  has a center wavelength is within the MIR range of approximately 2-20 microns. This MIR laser sources  12  provided herein are particularly useful because they can be tuned so that the output beam  16  has a wavelength that is not absorbed by the inclement conditions  22  in the atmosphere. For example, in cases of fog, water does not absorb in the 8-12 micron range. In this case, an output beam  16  having a center wavelength of approximately eight, nine, ten, eleven, or twelve microns from the MIR laser source  12  can pass through the inclement conditions  22  and will be visible in fog with the MIR imager  14 . Alternatively, if the inclement conditions  22  have a different absorption profile than water, the MIR laser source  12  can be adjusted to have a wavelength that is not absorbed by these particular inclement conditions  22  (different than the 8-12 micron range). 
     The design of the MIR laser source  12  can be varied to achieve the desired output beam. In one embodiment, the MIR laser source  12  is a semiconductor type laser that directly emits the output beam  16  that is within MIR range without any frequency conversion. As used herein, the term semiconductor shall include any solid crystalline substance having electrical conductivity greater than insulators but less than good conductors. 
       FIG. 2A  illustrates one example of a suitable MIR laser source  12  having features of the present invention that can be used in any of the embodiments disclosed herein. In this embodiment, the MIR laser source  12  includes a source frame  232 , a gain media (e.g. a quantum cascade (“QC”) gain media)  234 , a cavity optical assembly  236 , a power source  238  (illustrated in phantom), a temperature controller  239 , a laser electronic controller  240  (illustrated in phantom), an output optical assembly  242 , and a wavelength dependant (“WD”) feedback assembly  244  that cooperate to form an external cavity  248  laser that generates the output beam  16 . The design of each of these components can be varied pursuant to the teachings provided herein. In should be noted that the laser source  12  can be designed with more or fewer components than described above. For example, in one embodiment the laser source  12  may be designed without the external cavity  248  as discussed in more detail below. 
     The source frame  232  supports at least some of the components of the laser source  12 . In one embodiment, (i) the gain media  234 , the cavity optical assembly  236 , the output optical assembly  242 , and the WD feedback assembly  244  are each fixedly secured, in a rigid arrangement to the source frame  232 ; and (ii) the source frame  232  maintains these components in precise mechanical alignment to achieve the desired wavelength of the output beam  16 . In one embodiment, the WD feedback assembly is movable via a motor, screw, or other implementation, allowing tuning of the QC to achieve a variety of wavelengths. 
     Additionally, in  FIG. 2A , the power source  238 , the temperature controller  239 , and the laser electronic controller  240  are fixedly secured to the source frame  232 . With this design, all of the critical components are fixed to the source frame  232  in a stable manner, and the laser source  12  can be self-contained and extremely portable. Alternatively, for example, the power source  238 , the temperature controller  239 , and/or the laser electronic controller  240  can be separate from and external to the source frame  232 . 
     The design of the source frame  232  can be varied to achieve the design requirements of the laser source  12 . In  FIG. 2A , the source frame  232  includes a mounting base  232 A, and a cover  232 B. Alternatively, for example, the source frame  232  can be designed without the cover  232 B and/or can have a configuration different from that illustrated in  FIG. 2 . 
     The mounting base  232 A provides a rigid platform for fixedly mounting the gain media  234 , the cavity optical assembly  236 , the output optical assembly  242  and the WD feedback assembly  244 . In  FIG. 2A , the mounting base  232 A is illustrated as being generally rectangular plate shaped. In one embodiment, the mounting base  232 A is a monolithic structure that provides structural integrity to the laser source  12 . Alternatively, the mounting base  232  can have a configuration that is different than that illustrated in  FIG. 2A . 
     In certain embodiments, the mounting base  232 A is made of rigid material that has a relatively high thermal conductivity. In one non-exclusive embodiment, the mounting base  232 A has a thermal conductivity of at least approximately 170 watts/meter K. With this design, in addition to rigidly supporting the components of the MIR laser source  12 , the mounting base  232 A also readily transfers heat away from the QC gain media  234  to the temperature controller  239 . For example, the mounting base  232 A can be fabricated from a single, integral piece of copper, copper-tungsten or other material having a sufficiently high thermal conductivity. The one piece structure of the mounting base  232 A maintains the fixed relationship of the components mounted thereto and contributes to the small size and portability of the laser source  12 . 
     In  FIG. 2A , the cover  232 B is shaped somewhat similar to an inverted, open rectangular box, and the cover  232 B can include a transparent window  232 C that allows the output beam  16  to pass through the cover  232 B. In one embodiment, the cover  232 B is hermetically sealed to the mounting base  232 A in an air tight manner. This allows the source frame  232  to provide a controlled environment around some of the components. For example, a cover cavity  232 D formed by the source frame  232  can be filled with a gas such as nitrogen or an air/nitrogen mixture to keep out moisture and humidity; or the cover cavity  232 D can be subjected to a vacuum. 
     In certain embodiments, because of the design of the MIR laser source  12 , the overall size of the source frame  232  is quite small. For example, the source frame  232  can have dimensions of approximately 20 centimeters (height) by 20 centimeters (width) by 20 centimeters (length) (where length is taken along the propagation direction of the laser beam) or less, and more preferably, the source frame  12  has dimensions of approximately 3 centimeters (height) by 4 centimeters (width) by 5 centimeters (length). Still alternatively, the source frame  232  can have dimensions of less than approximately 10 millimeters (height) by 25 millimeters (width) by 30 millimeters. 
     In one embodiment, the gain media  234  can be a quantum cascade (“QC”) gain media that is a unipolar semiconductor laser that includes a series of energy steps built into the material matrix while the crystal is being grown. As used herein the term QC gain media  234  shall also include Interband Cascade Lasers (ICL). ICL lasers use a conduction-band to valence-band transition as in the traditional diode laser. 
     In one, non-exclusive embodiment, the semiconductor QCL laser chip is mounted epitaxial growth side down and a length of approximately four millimeters, a width of approximately one millimeter, and a height of approximately one hundred microns. A suitable QC gain media  234  can be purchased from Alpes Lasers, located in Switzerland. 
     In  FIG. 2A , the gain media  234  includes (i) a first facet  234 A that faces the cavity optical assembly and the WD feedback assembly  244 , and (ii) a second facet  234 B that faces the output optical assembly  242 . In this embodiment, the QC gain media  234  emits from both facets. 
     In one embodiment, the first facet  234 A is coated with an anti-reflection (“AR”) coating and the second facet  234 B is coated with a reflective coating. The AR coating allows light directed from the gain media  234  at the first facet  234 A to easily exit the gain media  234  and allows the light reflected from the WD feedback assembly  244  to easily enter the QC gain media  234 . In contrast, the reflective coating reflects at least some of the light that is directed at the second facet  234 B from the gain media  234  back into the gain medium  234 . In one non-exclusive embodiment, the AR coating can have a reflectivity of less than approximately 2 percent, and the reflective coating can have a reflectivity of between approximately 2-95 percent. In this embodiment, the reflective coating acts as an output coupler for the external cavity  248 . 
     The gain media  234  generates quite a bit of heat if operated continuously. Accordingly, the temperature controller  239  can be an important component that is needed to remove the heat, thereby permitting long lived operation of the laser source  12  and consistent optical output power. 
     The cavity optical assembly  236  is positioned between the gain media  234  and the WD feedback assembly  244  along a lasing axis, and collimates and focuses the light that passes between these components. For example, the cavity optical assembly  236  can include one or more lens. For example, the lens can be an aspherical lens having an optical axis that is aligned with the lasing axis. In one embodiment, to achieve the desired small size and portability, the lens has a relatively small diameter. In alternative, non-exclusive embodiments, the lens has a diameter of less than approximately 5 or 10 millimeters, and a focal length of approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mm and any fractional values thereof. The lens  336  can comprise materials selected from the group of Ge, ZnSe, ZnS Si, CaF, BaF or chalcogenide glass. However, other materials may also be utilized. The lens may be made using a diamond turning or molding technique. The lens can be designed to have a relatively large numerical aperture (NA). For example, the lens  336  can have a numerical aperture of at least approximately 0.6, 0.7, or 0.8. The NA may be approximated by the lens diameter divided by twice the focal length. Thus, for example, a lens diameter of 5 mm having a NA of 0.8 would have a focal length of approximately 3.1 mm. 
     The power source  238  provides electrical power for the gain media  234 , the laser electronic controller  240 , and the temperature controller  239 . In  FIG. 2A , the power source  238  is a battery that is secured to the source frame  232 . For example, the battery can be nickel metal hydrate. Alternatively, the power source  238  can be external to the source frame  232 . For example, for designs where the MIR laser source  12  is fixed to the ground, the power source  238  can be a power outlet or external battery. 
     The temperature controller  239  can be used to control the temperature of the QC gain media  234 , the mounting base  232 A, and/or one or more of the other components of the MIR laser source  12 . In one embodiment, the temperature controller  239  includes a thermoelectric cooler  239 A and a temperature sensor  239 B. The thermoelectric cooler  239 A may be controlled to effect cooling or heating depending on the polarity of the drive current thereto. In  FIG. 2A , the thermoelectric cooler  239 A is fixed to the bottom of the mounting base  232 A so that the thermoelectric cooler  239 A is in direct thermal communication with the mounting base  232 A, and so that the thermoelectric cooler  239 A can provide additional rigidity and support to the mounting base  232 A. Alternatively, an intermediate plate (not shown) may be attached between the thermoelectric cooler  239 A and the mounting base  232 A. The temperature sensor  239 B (e.g. a thermistor) provides temperature information that can be used to control the operation of the thermoelectric cooler  239 A. 
     Additionally, or alternatively, the source frame  332  can be mounted to a heat sink (not shown) inside a larger housing (not shown) which may also contain additional equipment including cooling fans and vents to further remove the heat generated by the operation of the laser source  12 . 
     The laser electronic controller  240  controls the operation of the laser source  12  including the electrical power that is directed to the gain media  234  and the temperature controller  239 . For example, the laser electronic controller  240  can include a processor that controls the gain media  234  by controlling the electron injection current. In  FIG. 2A , the laser electronic controller  240  is rigidly and fixedly mounted to the source frame  232  so that the laser source  12  is portable and rugged. Alternatively, for example, the laser electronic controller  240  can be external to the source frame  232 . 
     As provided herein, the laser electronic controller  240  can direct power to the gain media  234  in a fashion that minimizes heat generation in, and power consumption of the gain media  234  while still achieving the desired average optical power of the output beam  16 . With this design, the gain media  234  operates efficiently because it is not operating at a high temperature, the need to actively cool the gain media  234  is reduced or eliminated, and the laser source  12  can be powered with a relatively small battery. One example of how power can be directed to the gain media  134  is described in more detail below and illustrated in  FIG. 3 . 
     The output optical assembly  242  is positioned between the gain media  234  and the window  232 D in line with the lasing axis, and the output optical assembly  242  collimates and focuses the light that exits the second facet  234 B of the gain media  234 . For example, the output optical assembly  242  can include one or more lens that is somewhat similar in design to the lens of the cavity optical assembly  236 . 
     The WD feedback assembly  244  reflects the light back to the QC gain media  234 , and is used to precisely adjust the lasing frequency of the external cavity  248  and the wavelength of the output beam  16 . In this manner, the output beam  16  may be tuned and set to a desired fixed wavelength with the WD feedback assembly  244  without adjusting the QC gain media  234 . Thus, in the external cavity  248  arrangements disclosed herein, the WD feedback assembly  244  dictates what wavelength will experience the most gain and thus dominate the wavelength of the output beam  16 . 
     In certain embodiments, the WD feedback assembly  244  includes a wavelength dependent (“WD”) reflector  244 A that cooperates with the reflective coating on the second facet  234 B of the QC gain media  234  to form the external cavity  248 . The term external cavity  248  is utilized to designate the WD reflector  244 A positioned outside of the QC gain media  234 . 
     Further, the WD reflector  244 A can be accurately tuned to adjust the lasing frequency of the external cavity  248  and the wavelength of the output beam  16 , and the relative position of the WD reflector  244 A can be adjusted to tune the MIR laser source  12 . More specifically, the WD reflector  244 A can be tuned to cause the MIR laser source  12  to generate the MIR beam  16  that is fixed at a precisely selected specific wavelength in the MIR range. With the present invention, the MIR laser source  12  can be tuned so that the MIR beam  16  is at a wavelength that allows for maximum transmission through and minimum attenuation by the atmosphere. Stated in another fashion, the wavelength of the MIR beam  16  is specifically selected to avoid the wavelengths that are readily absorbed by water, carbon dioxide, or other inclement conditions. 
     As non-exclusive examples, the WD feedback assembly  244  can be adjusted so that the MIR laser source  12  has an output beam  16  with a wavelength of approximately (i) five microns, (ii) eight microns, (iii) nine microns, or (iv) ten microns, or any other specific wavelength in the MIR range. In certain embodiments, with the designs provided herein, the MIR beam  16  has a relatively broad line width. In alternative, non-exclusive embodiments, the output beam  16  can have a linewidth of less than approximately 50 cm-1. The spectral width of the output beam  16  can be adjusted by adjusting the cavity parameters of the external cavity. For example, the spectral width of the output beam  16  can be increased by increasing the focal length of the cavity optical assembly  236 . 
     The design of the WD feedback assembly  244  and the WD reflector  244 A can vary pursuant to the teachings provided herein. Non-exclusive examples of a suitable WD reflector  244 A includes a diffraction grating, a MEMS grating, prism pairs, a thin film filter stack with a reflector, an acoustic optic modulator, or an electro-optic modulator. 
     The type of adjustment done to the WD reflector  244 A to adjust the lasing frequency of the external cavity  248  and the wavelength of the output beam  16  will vary according to the type of WD reflector  244 A. For example, if the WD reflector  244 A is a diffraction grating, rotation of the diffraction grating relative to the lasing axis and the QC gain media  234  adjusts the lasing wavelength and the wavelength of the output beam  16 . More specifically, changing the incidence angle on the WD reflector  244 A serves to preferentially select a single wavelength which is the first order diffracted light from the reflector surface. This light is diffracted back onto the same path as the incident beam to thereby tune the external cavity  248  to the diffracted wavelength. The diffracted laser light is received by the QC gain media  234  to provide stimulated laser emission thereby resonating the QC gain media  234  with the grating selected wavelength. 
     There are many different ways to precisely rotate and fix the position of the diffraction grating. In  FIG. 2A , the WD feedback assembly  244  includes a pivot  244 B (e.g. a bearing or flexure) that secures WD reflector  244 A to the source frame  232 , and an adjuster  244 C (e.g. a threaded screw) that can be rotated by an actuator  244 D (or manually) to adjust the angle of the WD reflector  244 A. It should be noted that the position of the WD reflector  244 A can be adjusted during manufacturing to obtain the desired wavelength of the output beam  16 . 
     Alternatively, the actuator  244 D can be controlled to precisely rotate the WD reflector  244 A during operation of the MIR laser source  12  so that the MIR laser source  12  sequentially generates an output beam  16 , with each subsequent output beam  16  having a different center wavelength that is within the MIR range. 
     Further, it should be noted that MIR laser source  12  is tunable to a small degree by changing the temperature of the QC gain media  234  with the temperature controller  239  or by variation of the input current to the QC gain media  234 . 
       FIG. 2B  is a simplified side illustration of another embodiment of a MIR laser source  212 B that is somewhat similar to the MIR laser source  12  illustrated in  FIG. 2A  and described above. However, in  FIG. 2B , the first facet  234 AB of the QC gain media  234  is coated with a high reflective (“HR”) coating inhibits the photons from exiting the first facet  234 AB, reflecting them back into the wave guide to facilitate lasing. In one non-exclusive example, the HR coating can have a reflectivity of greater than approximately 95 percent for the wavelength of the QC gain media  234 B. In this embodiment, the MIR laser source  212 B still emits from the second facet  234 BB, but the MIR laser source  212 B does not have an external cavity  248  (illustrated in  FIG. 2B ). 
       FIG. 2C  is a simplified side illustration of another embodiment of another MIR laser source  212 C having features of the present invention. In this embodiment, the MIR laser source  212 C includes a plurality of QC gain medias  234 C (three are illustrated) that each generates an output beam  216 C that is combined to form an overall output beam  217 . It should be noted that many of the components necessary to combine the output beams  216 C and tune the QC gain medias  234 C have been omitted from  FIG. 2C . 
     With the design illustrated in  FIG. 2C , in one embodiment, each QC gain media  234 C can be tuned to produce an output beam  216 C having a different center wavelength in the MIR range. As a result thereof, the resulting overall output beam  217  can include multiple discrete wavelengths. With this design, each of the QC gain medias  234 C can be tuned to generate an output beam  216 C that propagates through a different inclement condition  22  (illustrated in  FIG. 1 ). 
       FIG. 2D  is a simplified side illustration of yet another embodiment of another MIR laser source  212 D having features of the present invention. In this embodiment, the MIR laser source  212 D includes a plurality of QC gain medias  234 D (three are illustrated) that each generates an output beam  216 D. It should be noted that many of the components necessary to tune the QC gain medias  234 D have been omitted from  FIG. 2D . 
     With the design illustrated in  FIG. 2D , in one embodiment, each QC gain media  234 D can be tuned to produce an output beam  216 D having a different center wavelength in the MIR range. With this design, each of the QC gain medias  234 D can be tuned to generate an output beam  216 D that propagates through a different inclement condition  22  (illustrated in  FIG. 1 ). 
       FIG. 3  is a graph that illustrates one non-exclusive embodiment of a power profile (power versus time) directed to a gain media  234  (illustrated in  FIG. 2 ). In one embodiment, the laser electronic controller  240  (illustrated in  FIG. 2 ) pulses the power (as opposed to constant power) directed to the gain media  234  in a low duty cycle wave form. In alternative non-exclusive embodiments, the laser electronic controller  240  controls the duty cycle (ratio of the amount of time at peak power over the total cycle time) to be approximately 0.5%, 5%, 10%, 15%, 20%, or 100%. 
     As provided herein, in one non-exclusive example, the laser electronic controller  240  directs approximately 1-20 watts peak electrical power for a relatively short period of time (e.g. 100-200 nanoseconds), and the laser electronic controller  240  directs low or no power to the gain media  234  between the peaks. With this design, relatively high power is directed to the gain media  234  for short, spaced apart periods of time. As a result thereof, the gain media  234  lases with little to no heating of the core of the gain media  234 , the average power directed to the gain media  234  is relatively low, and the desired average optical power of the output beam  16  can be efficiently achieved. It should be noted that as the temperature of the gain media  234  increases, the efficiency of the gain media  234  decreases. With this embodiment, the pulsing of the gain media  234  keeps the gain media  234  operating efficiently, minimizes heat generation, and the overall system utilizes relatively low power. As a result thereof, the MIR laser source  12  can be battery powered. 
     It should be noted that the pulsed power to the QC gain media  234  can be used in concert with the MIR imager  16  (illustrated in  FIG. 1 ) to enable signal processing techniques to improve image quality. For example, MIR imager  16  can be controlled to capture the images  18  in conjunction with the pulses of power directed to the QC gain media  234 . This feature is described in more detail with reference to  FIG. 4B . 
     Alternatively, the laser electronic controller  240  directs constant power (as opposed to pulsed power) to the gain media  234 . 
       FIG. 4A  is a simplified side illustration of one, non-exclusive embodiment of the MIR imager  14 . In this embodiment, the MIR imager  14  includes a capturing system  452  (illustrated as a box in phantom) that captures information of the scene in front of the MIR imager  14 ; a lens assembly  454  that focuses light on the capturing system  452 ; and an imager control system  456  in addition to the imager display  26  (illustrated away from the rest of the MIR imager  14 ). The design of each of these components can be varied to achieve the desired resolution of the MIR imager  14 . Further, for example the MIR imager  14  could be designed with fewer or more components than are illustrated in  FIG. 4A . 
     In one embodiment, the capturing system  452  include an image sensor  452 A (illustrated in phantom), a filter assembly  452 B (illustrated in phantom), and a storage system  452 C (illustrated in phantom). The image sensor  452 A receives the light that passes through the filter assembly  452 B and converts the light into electricity. Non-exclusive examples of suitable image sensors  452 A can include a family of image sensors known as thermal electric cameras, vanadium oxide, microbolometers, quantum well infrared photodetectors, or thermal light valve technology sold by Redshift Systems Corporation, located in Burlington, Mass. The filter assembly  452 B limits the wavelength of the light that is directed at the image sensor  452 A. For example, the filter assembly  452 B can be designed to transmit all light in the MIR range, and block all light having a wavelength that is greater or lesser than the MIR range. Alternatively, the filter assembly  452 B can be designed to transmit light at only a selected portion (e.g. the 8-12 micron range) of the MIR range, and block all light having a wavelength that is greater or lesser than the selected portion of the MIR range. 
     The storage system  452 C stores the various images. Non-exclusive examples of suitable storage systems  452 C include flash memory, a floppy disk, a hard disk, or a writeable CD or DVD. 
     The imager control system  456  is electrically connected to and controls the operation of the electrical components of the MIR imager  14 . The imager control system  456  can include one or more processors and circuits and the control system  456  can be programmed to perform one or more of the functions described herein. The imager control system  456  receives information from the image sensor  452 A and generates the image  18 . Additionally, or alternatively, the image control system  456  can further enhance the image  18  with color or other features that will further identify the located object  20 . 
     The imager display  26  can be an LCD screen or another type of display that is capable of displaying the image  18 . 
     In one embodiment, the MIR imager  14  is power by an external source, such as the vehicle  24  (illustrated in  FIG. 1 ). Alternatively, the MIR imager  14  can be portable and can be powered by a battery. 
       FIG. 4B  is a simplified side illustration of another embodiment of a MIR imager  414  having features of the present invention. In this embodiment, to generate each displayed image  418 , the capturing system  452 B (illustrated as a box in phantom) is controlled by the image control system  456 B to capture an illuminated first image (frame)  419  when the MIR laser source  12  (illustrated in  FIG. 1 ) is illuminating the scene, and a non-illuminated second image (frame)  421  when the MIR laser source  12  is not illuminating the scene. For example, the first image  419  can be captured when the pulsed power is directed to the MIR laser source  12 , and the second image  421  can be captured when the pulsed power is not directed to the MIR laser source  12 . With this design, the MIR imager  414 B captures the image frames  419 ,  421  in synchronization with one or more pulses of the MIR laser source  12 . 
     In this example, the image control system  456 B can make use of frame subtraction to enhance the contrast of the beam in certain applications. More specifically, the image control system  456 B can subtract the second image  421  from the first image  419  to generate the displayed image  418  that is displayed on the display  426 . In this way, the contrast of the MIR laser source  12  on a target is enhanced by subtracting the non-illuminated frame  421  from the illuminated frame  419 . 
       FIG. 5  illustrates a combination with another embodiment of how an optical illuminator assembly  510  is useful for locating and/or seeing an object  520  in inclement conditions  522  (illustrated as small circles). The embodiment illustrated in  FIG. 5  is somewhat similar to the embodiment illustrated in  FIG. 1 . In  FIG. 5 , the plurality of spaced apart MIR laser sources  512  are again positioned near the object  520 , the MIR imager  514  is again secured to the vehicle  524 , and the MIR laser sources  512  and the MIR imager  514  are again spaced apart. However, in this example, the object  520  is a harbor inlet to a harbor, and the vehicle  524  is a boat. With this design, a person  528  operating the vehicle  524  will be able to locate the harbor inlet  520  in inclement conditions  522 . 
     In  FIG. 5 , the plurality of spaced apart MIR laser sources  512  are positioned near and line the harbor inlet  520 , and each MIR laser source  512  generates the output beam  516  that is directed generally upward. For example, the MIR laser sources  512  can partly or fully line one or both sides of the harbor inlet  520 . In  FIG. 5 , the MIR laser sources  512  are positioned adjacent to both sides of the harbor inlet  520 . Alternatively, or additionally, one or more laser sources  512  may be used at one end of a channel  517  to provide directional guidance to guide a boat directly down a safe course or channel. 
     In  FIG. 5 , the MIR imager  514  is secured to the boat frame and the MIR imager  514  includes an imager display  526  (illustrated away from the MIR imager  514  for clarity) that is viewable by a user  528 , e.g. a boat captain. For example, the imager display  526  can be secured to the dash of the boat  524 . Alternatively, the imager display  526  can be incorporated into goggles worn by the user  528 . Still alternatively, the entire MIR imager  514  can be incorporated into goggles worn by the user  528 . 
     In  FIG. 5 , the MIR imager  514  is directed horizontally towards the harbor inlet  520 , and the image  518  provided the MIR imager  514  includes a plurality of beams of light  530  that are positioned adjacent to the harbor inlet  520 . With this design, the optical illuminator assembly  10  is useful for the boat captain  528  to locate (“see”) the outline of the harbor inlet  520  in inclement conditions  522 . 
       FIG. 6  illustrates a combination including another embodiment of how an optical illuminator assembly  610  is useful for locating and/or seeing an object  620  in inclement conditions  622  (illustrated as small circles). In  FIG. 6 , a single MIR laser source  612  is positioned near the MIR imager  614  (e.g. on the same side of the inclement conditions  622 ), and both the MIR laser source  612  and the MIR imager  614  are secured to the vehicle  624 . Moreover, in this example, the object  620  is an airport runway, and the vehicle  624  is an aircraft. With this design, a person  628  operating the vehicle  624  will be better able to locate the airport runway  620  in inclement conditions  622 . 
     In  FIG. 6 , the MIR laser source  612  generates the output beam  616  that is directed generally forward and downward. Further, in  FIG. 6 , both the MIR laser source  612  and the MIR imager  614  are secured to the aircraft  624  and the MIR imager  614  includes the imager display  626  (illustrated away from the MIR imager  614  for clarity) that is viewable by a user  628 , e.g. a pilot. For example, the imager display  626  can be secured to the dash of the aircraft  624 . Alternatively, the imager display  626  can be incorporated into goggles worm by the user  628 . Still alternatively, the entire MIR imager  614  and possible the MIR laser source  612  can be incorporated into goggles worm by the user  628 . 
     In this example, the image  618  captured by the MIR imager  614  includes at least a portion of the object  620  illuminated by the output beam  616  from the MIR laser source  612 . With this design, the pilot  628  will be better equipped to locate the runway in inclement conditions  622 . 
     In one embodiment, the output beam  616  and the MIR imager  614  can be moved relative to the aircraft  624 . For example, in one embodiment, the output beam  616  and the MIR imager  614  can be moved (manually or electrically) side to side and/or up and down to change the area in which the MIR imager  614  is viewing. 
     In  FIG. 6 , the image  618  provided the MIR imager  614  includes a portion of the runway  630  that is illuminated by the output beam  616 . Backscattered light from the runway is captured by the MIR imager  614  to enhance the image  618  of the object  620 . With this design, the optical illuminator assembly  610  is useful for the pilot  628  to illuminate the runway  620  in inclement conditions  622  for better visibility through the MIR imager  614 . 
       FIG. 7  illustrates a combination including still another embodiment of how an optical illuminator assembly  710  is useful for locating and/or seeing an object  720  in inclement conditions  722  (illustrated as small circles). The embodiment illustrated in  FIG. 7  is somewhat similar to the embodiment illustrated in  FIG. 6 . However, in this example, the object  720  is a harbor inlet to a harbor, and the vehicle  724  is a boat. With this design, a person  728  operating the vehicle  724  will be able to locate the harbor inlet  720  in inclement conditions  722 . 
     In  FIG. 7 , the MIR laser source  712  generates the output beam  716  that is directed generally forward. Further, in  FIG. 7 , both the MIR laser source  712  and the MIR imager  714  are secured to the boat  724  and the MIR imager  714  includes the imager display  726  (illustrated away from the MIR imager  714  for clarity) that is viewable by a user  728 , e.g. a boat captain. For example, the imager display  726  can be secured to the dash of the boat  724 . Alternatively, the imager display  726  can be incorporated into goggles worm by the user  728 . Still alternatively, the entire MIR imager  714  and possible the MIR laser source  712  can be incorporated into goggles worm by the user  728 . 
     In this example, the image  718  captured by the MIR imager  714  again includes at least a portion of the object  720  illuminated by the output beam  716  from the MIR laser source  712 . 
     In one embodiment, the output beam  716  and the MIR imager  714  can be moved relative to the boat  724 . For example, in one embodiment, the output beam  716  and the MIR imager  714  can be moved side to side and/or up and down to change the area in which the MIR imager  714  is viewing. 
     In  FIG. 7 , the image  718  provided the MIR imager  714  includes a portion of the harbor inlet  730  that is illuminated by the output beam  716 . Backscattered light from the harbor inlet is captured by the MIR imager  714  to enhance the image  718  of the object  720 . With this design, the optical illuminator assembly  710  is useful for the boat captain  728  to locate the harbor inlet in inclement conditions  722 . 
       FIG. 8  illustrates a combination including another embodiment of how an optical illuminator assembly  810  is useful for locating and/or seeing an object  820  in inclement conditions  822  (illustrated as small circles). The embodiment illustrated in  FIG. 8  is somewhat similar to the embodiment illustrated in  FIGS. 6 and 7 . However, in this example, the object  820  is a tree, and the vehicle  824  is a tank. With this design, a person  828  operating the vehicle  824  will be able to locate the tree  820  or any other object to better navigate the tank  824  in inclement conditions  822 . 
     In  FIG. 8 , the MIR laser source  812  generates the output beam  816  that is directed generally forward and downward. Further, in  FIG. 8 , both the MIR laser source  812  and the MIR imager  814  are secured to the tank  824  and the MIR imager  814  includes the imager display  826  that is viewable by a user  828 , e.g. a tank driver. For example, the imager display  826  can be secured to the dash of the tank  824 . Alternatively, the imager display  826  can be incorporated into goggles worm by the user  828 . Still alternatively, the entire MIR imager  814  and possible the MIR laser source  812  can be incorporated into goggles worm by the user  828 . 
     In this example, the image  818  captured by the MIR imager  814  again includes at least a portion of the object  820  illuminated by the output beam  816  from the MIR laser source  812 . In this embodiment, the output beam  816  and the MIR imager  814  can be moved relative to the tank  824 . 
     In  FIG. 8 , the image  818  provided the MIR imager  814  includes the tree  830  and a portion of the terrain that is illuminated by the output beam  816 . Backscattered light from the terrain is captured by the MIR imager  814  to enhance the image  818  of the object  820 . 
       FIG. 9  illustrates a combination including still another embodiment of how an optical illuminator assembly  910  is useful for locating and/or seeing an object  920  in inclement conditions  922  (illustrated as small circles). The embodiment illustrated in  FIG. 9  is somewhat similar to the embodiment illustrated in  FIGS. 6-8 . In this example, the object  920  is a tree, and the vehicle  924  is a car. With this design, a person  928  operating the vehicle  924  will be able to locate the tree  920  or any other object to better navigate the car  924  in inclement conditions  922 . 
     In  FIG. 9 , the MIR laser source  912  generates the output beam  916  that is directed generally forward. Further, in  FIG. 9 , both the MIR laser source  912  and the MIR imager  914  are secured to the car  924  and the MIR imager  914  includes the imager display  926  that is viewable by a user  928 , e.g. a car driver. For example, the imager display  926  can be secured to the dash of the car  924 . Alternatively, the imager display  926  can be incorporated into goggles worm by the user  928 . Still alternatively, the entire MIR imager  914  and possible the MIR laser source  912  can be incorporated into goggles worm by the user  928 . 
     In this example, the image  918  captured by the MIR imager  914  again includes at least a portion of the object  920  illuminated by the output beam  916  from the MIR laser source  912 . In  FIG. 9 , the image  918  provided the MIR imager  914  includes the tree  930  and a portion of the terrain that is illuminated by the output beam  916 . More specifically, backscattered light from the terrain is captured by the MIR imager  914  to enhance the image  918  of the object  920 . Moreover, in this embodiment, the output beam  916  and the MIR imager  914  can be moved relative to the car  924 . 
       FIG. 10  illustrates a combination that includes another embodiment of how an optical illuminator assembly  1010  is useful for locating and/or seeing an object  1020  in inclement conditions  1022  (illustrated as small circles). The embodiment illustrated in  FIG. 10  is somewhat similar to the embodiments illustrated in  FIGS. 6-9 . However, in this example, the optical illuminator assembly  1010  is a hand held device that is used by a person  1028  to locate the object  1020  (illustrated as a box). 
     In  FIG. 10 , the MIR laser source  1012  generates the output beam  1016  that is directed generally forward. Further, in  FIG. 10 , both the MIR laser source  1012  and the MIR imager  1014  are secured to a common housing, and the MIR imager  1014  includes the imager display  1026  that is viewable to the person  1028 . Alternatively, the MIR laser source  1012  can be in a separate housing from the MIR imager  1014 . Further, the MIR laser source  1012  and the MIR imager  1014  can share a common battery assembly  1029  or have separate batteries. 
     In the example illustrated in  FIG. 10 , the image  1018  captured by the MIR imager  1014  again includes at least a portion of the object  1020  illuminated by the output beam  1016  from the MIR laser source  1012 . In  FIG. 10 , the image  1018  provided the MIR imager  1014  includes the box  1030 . In this embodiment, backscattered light from the area is captured by the MIR imager  1014  to enhance the image  1018  of the object  1020 . 
     In this embodiment, the optical illuminator assembly  1010  can be moved by the person to change the area in user is viewing. 
       FIG. 11  illustrates a combination including another embodiment of how an optical illuminator assembly  1110  is useful for locating and/or seeing an object  1120  in inclement conditions  1122  (illustrated as small circles). The embodiment illustrated in  FIG. 11  is similar to the embodiment illustrated in  FIG. 10 . However, in this example, the optical illuminator assembly  1110  is incorporated into a binocular assembly  1131  that can be worn as goggles (or hand held) by the person  1128  to locate the object  1120  (illustrated as a box). In this embodiment, the goggles  1131  includes an attacher  1133  (e.g. a strap or helmet) for securing the goggles  1131  to the person  1128 . 
     In  FIG. 11 , the MIR laser source  1112  generates the output beam  1116  that is directed generally forward. Further, in  FIG. 11 , both the MIR laser source  1112  and the MIR imager  1114  are secured to a common housing, and the MIR imager  1114  includes the imager display  1126  that is viewable the person  1128 . Alternatively, the MIR laser source  1112  can be in a separate housing from the MIR imager  1114  and/or the imager display  1126  may be the only component incorporated into the goggles. 
     In this example, the image  1118  captured by the MIR imager  1114  again includes at least a portion of the box  1130  illuminated by the output beam  1116  from the MIR laser source  1112 . In  FIG. 11 , the image  1218  provided the MIR imager  1214  includes the box  1130 . In this embodiment, backscattered light from the area is captured by the MIR imager  1114  to enhance the image  1118  of the object  1120 . 
     In this embodiment, the optical illuminator assembly  1110  can be moved by the person to change the area in user is viewing. 
       FIG. 12  illustrates a combination including another embodiment of how an optical illuminator assembly  1210  is useful for locating and/or seeing an object  1220  in inclement conditions  1222  (illustrated as small circles). In this example, the optical illuminator assembly  1210  is incorporated into a weapon sight  1235  of a weapon  1237  (such as a gun, or shoulder fired missile) that is viewable by the person  1228  to locate the object  1220 , e.g. a target or game (illustrated as a box) or in one embodiment, to provide a spot of light on the target that is bore-sighted to the gun for aiming purposes. In one embodiment, the size of the beam may be adjustable to allow a wide beam for general illumination or a narrow beam for aiming. 
     In  FIG. 12 , the MIR laser source  1212  generates the output beam  1216  that is directed generally forward. Further, in  FIG. 12 , both the MIR laser source  1212  and the MIR imager  1214  are secured to a common housing, and the MIR imager  1214  includes the imager display  1226  that is viewable the person  1228 . Alternatively, the MIR laser source  1212  can be in a separate housing from the MIR imager  1214 . 
     In this example, the image  1218  captured by the MIR imager  1214  again includes at least a portion of the object  1220  illuminated by the output beam  1216  from the MIR laser source  1212 . In  FIG. 12 , the image  1218  provided the MIR imager  1214  includes the target  1230 . 
     There are many uses for the optical illuminator assembly disclosed herein, and only of few, non-exhaustive examples are illustrated in the Figures. Many of these systems are useful to (i) first responders, e.g. fireman and other rescue service personnel that need to enter atmospheres filled with smoke and other particulates to rescue trapped individuals and to try to stop further damage, (ii) law enforcement and intelligence workers would benefit from technology enabling surveillance operations to continue in all weather and light conditions, (iii) security monitoring workers would benefit from technology enabling the monitoring of entrances and fence lines, (iv) soldiers benefit from the ability to target through inclement weather, or (v) recreational people, e.g. hunters and hikers etc. would benefit from being able to see in inclement weather conditions. 
     The various embodiments disclosed herein have one thing in common in that they use a MIR light source. This offers illumination in a variety of atmospheric conditions where other wavelengths of light would be absorbed. In essence this technology enables operation in all weather and light conditions. So any situation where seeing through an otherwise opaque atmosphere would be useful should be covered by the invention description. The systems will also work at night and other low to zero light conditions, such as in caves where cold temperatures may have stabilized, thereby limiting the effectiveness of thermal cameras alone. 
     While the particular optical illuminator assembly as shown and disclosed herein is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.