Abstract:
An illumination device utilizes one or more laser array emitters to provide a compact, high power light source useful for illuminating objects or areas of interest and in searching for items that may fluores when illuminated by light that interacts with material in or on the items. The illumination device is capable of providing a retina safe output at an object based on the distance from the illuminator to the object.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional patent application Ser. No. 60/945,389 filed Jun. 21, 2007. The entire disclosure of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]      FIG. 1  discloses an illumination device that requires multiple individually aligned lasers or LEDs. Reflections or secondary emissions bouncing off of an object or area of interest may be seen with night vision equipment, infrared or other imagers, or the naked eye. 
         [0003]    Current implementations of illumination devices also require that each individual diode be separately mounted and aligned to illuminate the target at a distance with parallel beams. It has not been possible to combine the power of many diodes in the same mechanical and optical structure without great difficulty in mounting and aiming the devices, which are currently separately contained in individual packages. 
         [0004]    It has been possible for some time to manufacture many laser diodes on a single wafer as vertical cavity emitting devices (VCSELS) and separate them for use as individual lasers. It has also been possible to capture the energy of an array of devices in a carefully constructed and connectorized array of fiber optic lines to transmit the laser signal emitted from the individual diodes for the purpose of high density interconnects between servers and routers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a photograph of an illumination device that employs multiple individual laser diodes. 
           [0006]      FIGS. 2A and 2B  are photographs of multi-element single-color laser array emitter devices consistent with an embodiment of the invention. 
           [0007]      FIG. 3  is a photograph of an illumination device consistent with an embodiment of the invention. 
           [0008]      FIG. 4  is a block diagram of a first illumination device consistent with an embodiment of the invention. 
           [0009]      FIG. 5  is a photograph of a multi-element multi-color laser array emitter device consistent with an embodiment of the invention. 
           [0010]      FIG. 6  is a block diagram of a second illumination device consistent with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    In one embodiment, the illumination device uses one or more arrays of vertical or edge emitting laser diodes or light emitting diodes (LEDs) to provide a high power beam in order to illuminate an object or area of interest or interrogate the environment and reveal through fluorescence, reflection, or other emissions, the presence of materials that may be of interest.  FIG. 2A and 2B  show a multi-element single-color laser array emitter device  100  with an output beam  102  that may be used in an illumination device consistent with one embodiment of the invention. The wavelength of the output beam  102  may be determined by a selected non-linear crystal. 
         [0012]    In one embodiment, the laser arrays could be similar in format to the “NECSEL” arrays available from Novalux Inc., which have been designed for use in projection devices, rear projection television sets, cell phone, and PDA projectors. The vertical cavity (VCSEL) array format is desirable because the devices are created on a single wafer and are capable of transmitting vertically perpendicular to the wafer surface and replace the need for one or more individually packaged laser diodes that must be mechanically mounted and optically aligned to form beams traveling in the same direction. One or more array devices disposed side by side on the same wafer and transmitting in the same direction offer increased power per unit area (or volume) by a factor of 10 to 30 times (depending on the number of emitters) when compared to individually packaged and separately mounted laser diodes. The array devices can significantly lower cost by reducing the time-consuming effort of alignment. Additional mechanical parts that may be susceptible to production variability and potential misalignment due to shock, temperature, and vibration can be eliminated. Wafer fabrication processes and photographic lithography processes help ensure that each vertically emitting laser structure is aligned with a high degree of accuracy to point and project their parallel beams in the same direction. 
         [0013]      FIG. 3  is a photograph of an illumination device  200 / 400  utilizing a solid state array emitter device consistent with an embodiment of the invention. The illumination device  200 / 400  may generate a multi-beam output  202 / 402 A,  402 B,  402 C used for marking, illuminating, or interrogating an object  204 . An adjustor knob  206 / 406  may be utilized to adjust the divergence of the output  202 / 402 A,  402 B,  402 C from a pointer (generally non diverging beam) to an illuminator (generally diverging beam). Reflections and secondary emissions  208  bouncing off of the object  204  or area of interest may be seen with night vision equipment, infrared or other imagers, or the naked eye. These reflections or secondary emissions  208  may be used to interrogate the object  204 , for example, certain wavelengths of light may be used to cause a target to have energetic emission of photons through fluorescence and luminous excitation which can be interpreted by an operator or an imager. Additionally, the illumination device may be used for gas and biological detection. 
         [0014]      FIG. 4  is a block diagram of the first illumination device  200  consistent with an embodiment of the invention. An afocal beam expander having a first lens  212  with a −F 1  focal length and a second lens  214  having a F 2  focal length may be disposed a spaced distance F 2 −F 1  from the laser array emitter  216  to provide a collimated light output that extends through an aperture  218 . The illumination device  200  may be housed in a housing  210  that can be hand held, weapon-mounted, or mounted on a remotely controllable actuator. A user adjustable adjustor knob  206  may be coupled to the housing  210  and allow an operator to change the distance between the lenses  212 ,  214  to adjust the divergence of the light output  202  from the device  200  from narrow to wide. The device  200  may have an internal power supply  224 , for example a dry cell battery, or may receive power from a remote source. A selector  220  may allow a user to adjust the output power through a controller  234  and a variable laser driver circuit  226 . 
         [0015]    The illumination device  200  may also be used to project a beam for optical disruption. An optical disruption may be any interruption of the ability of the viewer to see clearly and/or discriminate objects or scenes in such a way that the viewer&#39;s perception is disrupted sufficiently to prevent efficient and effective cognitive action based on visual information. If the device  200  is to be used for optical disruption in such a way that it was intended to be “retina safe” it could be coupled to the output of a rangefinder  228  or other target range estimator. A retina safe level is often expressed as a maximum permissible exposure (MPE). MPE is the level of laser radiation to which a person may be exposed without hazardous effects or biological changes in the eye. MPE levels are determined as a function of laser wavelength, exposure time and pulse repetition (see ANSI Z136.1 Standard for the safe use of lasers). The MPE is usually expressed either in terms of radiant exposure in J/cm 2  or as irradiance in W/cm 2  for a given wavelength and exposure duration. 
         [0016]    The illumination device  200  may be wire or wirelessly coupled to the range finder  228  to determine the distance to the object  204 . The distance to target may be inputted into a look-up table  230  and then to the controller  234  and the variable laser driver circuit  226  to keep the power level at the object at or below the retina safe level. The detection of target range by the rangefinder  228  could control the amplitude of the output beam via a photo sensor  232  with the controller  234  to provide light output feedback to control the variable laser driver circuit  226 . The device  200  may be calibrated at the time of manufacture and the output beam  202  could be adjusted up or down in power to illuminate objects depending on the range so as not to exceed the retina safe limit. 
         [0017]    Alternatively, the output beam  202  could be controlled without active feedback by adjusting the output power based on the distance to target and calibrated output power levels stored in the look-up table  230 . 
         [0018]    The output beam  202  could also be modified by changes in the optics in front of the beam such that the divergence of the beam would make it retina safe at the distance measured by the rangefinder. An electrically controllable actuator  236  coupled to the controller  234  may control the distance between the first lens  212  and the second lens  214  to adjust the divergence. A combination of controlling the output power and changing the divergence may also be accomplished. 
         [0019]      FIG. 5  is a photograph of a multi-element multi-color laser array emitter device  300  consistent with an embodiment of the invention. The device  300  may have a plurality of array emitters capable of generating a plurality of outputs  302 A,  302 B,  302 C having differing wavelengths. The compact design of these array emitters allows them to be located in very close proximity with other wavelengths and thereby save overall system volume. It is possible to share driver electronics and cooling (heating) electronics and mechanical implementations. Multiple wavelengths can be co-located to achieve a smaller and more capable product while conserving overall power, volume, weight, heatsinking, or heater power consumption. 
         [0020]      FIG. 6  is a block diagram of a second illumination device  400  consistent with an embodiment of the invention. The illumination device  400  may have two or more laser array emitters  416 A,  416 B,  416 C capable of generating light at differing wavelengths. Aligned with each array emitter may be an afocal beam expander having a first lens  412  with a −F 1  focal length and a second lens  414  having a F 2  focal length may be disposed a spaced distance F 2 −F 1  from the laser array emitter  416 A,  416 B,  416 C to provide collimated light outputs  402 A,  402 B,  402 C that extend through an aperture  418 . The illumination device  400  may be housed in a housing  410  that can be hand held, weapon-mounted, or mounted on a remotely controllable actuator. A user adjustable adjustor knob  406  may be coupled to the housing  410  and allow an operator to change the distance between the lenses  412 ,  414  to adjust the divergence of the light output  402 A,  402 B,  402 C from the device  400  from narrow to wide. Alternatively, an electrically controllable actuator  436  coupled to the controller  434  may change the distance between the lenses  412 ,  414  to adjust the divergence of the light output  402 A,  402 B,  402 C. The device  400  may have an internal power supply  424 , for example a dry cell battery, or may receive power from a remote source. A selector  420  may allow a user to adjust the output power through the controller  434  and a variable laser driver circuit  426 . A selector  440  may allow a user to select the output color. 
         [0021]    Using a range finder  228  and a look-up table  430 , the controller  434  can adjust the output beams  402 A,  402 B,  402 C to be retina safe at the object being illuminated by adjusting the output of the emitter  416 A,  416 B,  416 C or by changing the divergence of the output beams  402 A,  402 B,  402 C. Similar control of the output power as noted above with reference to  FIG. 4  could be applied to any transmitted visible color (red, blue, green, etc., combination) such that the output beam would be retina safe. 
         [0022]    Although several embodiments have been described in detail herein, the invention is not limited hereto. It will be appreciated by those having ordinary skill in the art that various modifications can be made without materially departing from the novel and advantageous teachings of the invention. Accordingly, the embodiments disclosed herein are by way of example. It is to be understood that the scope of the invention is not to be limited thereby.