Abstract:
A method for laser return characterization in a DIRCM system, wherein the improvement comprises the step of using a split or shared path.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims rights under 35 USC §119(e) from U.S. patent application Ser. No. 60/920,713 filed Mar. 29, 2007, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to countermeasures systems and more particularly to methods for laser characterization in directed infrared countermeasures (DIRCM) systems. 
     2. Brief Description of Prior Developments 
     Countermeasures Effectiveness Assessment (CMEA) has been a major priority in the development of Directed Infrared Countermeasures (DIRCM) systems. The determination of when a threat is no longer lethal is a priority during multiple launches. The classification of threat helps with determining of jam code algorithms selection or allows provisos for alternate deterrents. Conventional approaches use the existing fine-track-sensor, IR imaging camera, to detect jam-laser optical return. Disadvantages of such conventional approaches may include the need for additional processing, camera blanking, long integration times, lack of camera sensitivity, and asynchronous returns. 
     SUMMARY OF INVENTION 
     The present invention is a method and apparatus for laser return characterization in a DIRCM system, wherein the improvement comprises the step of using a split or shared path. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is further defined with reference to the accompanying drawing where: 
         FIGS. 1A and 1B  are respectively vertical cross section schematic view of a preferred split path and shared path embodiment of the apparatus of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , the method of the present invention can be accomplished with slit or shared path. A single detector is added and dedicated to collect laser returns. The detector must be mounted on final stage of the gimbal. The response must be able to receive laser pulses with reticule information, assuming μsec. This unburdens the track camera from additional processing or limitations of integration time. Since the single detector becomes a background staring sensor the device can also be used to measure background noise to help with camera&#39;s AGC. 
     In this invention the correlating laser fire event with return time provides rangefinding data an added feature that will help in determination of the specific threat. The wavelength of the detector must be wide-band to enable correlation of missile types similar to PbSe. 
     Referring to  FIG. 1A , in the split path embodiment, there is a dome  10  and an embedded detector  12 . There is also a laser beam entrance point  14 , a beam combiner  16 , a TDA  18 , and a TOA  20 . 
     Referring to  FIG. 1B , there is a dome  22  and an embedded detector  24 , there is also a laser beam entrance port  26 , a TDA  28  and a TOA  30 . 
     While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.