Fused thermal and direct view aiming sight

Abstract

A fused thermal and a direct view aiming sight includes an optical gun sight, a thermal sight, and a beam combiner. The optical sight generates a direct view image of an aiming point or reticle superimposed on a target scene. The thermal sight generates a monochromic thermal image of the target scene. The combiner is positioned behind a 1× non-magnified optical sight and the thermal sight and in front of an exit pupil of the thermal sight. The combiner is positioned right behind the intermediate image plane of a magnified optical sight between an objective lens and an eyepiece. The combiner passes the direct view image and reflects the thermal image to the exit pupil to fuse the thermal image onto the direct view image for an operator to see at the exit pupil as a combined thermal and direct view optical image of the target scene together with the aiming reticle.

1 . An aiming sight comprising: 
 a magnified optical sight having an objective lens and a reticle which is placed at an intermediate image plane of the objective lens, the magnified optical sight having an exit pupil at a position behind an eyepiece lens assembly which collimates an image of a target scene at the intermediate image plane;    a thermal image sight assembly for generating a thermal image of the target scene; and    a spectral beam combiner assembly having a reflector positioned right behind the intermediate image plane such that the reflector is between the reticle and the eyepiece lens assembly, the reflector receives and passes the intermediate image having the superimposed aiming reticle from the magnified optical sight to the exit pupil and receives and reflects the thermal image from the thermal image sight assembly to the exit pupil such that the thermal image is superimposed over the intermediate image having the superimposed aiming reticle for an operator to see as one combined image when the operator positions an eye at the exit pupil.    
   
   
       2 . The aiming sight of  claim 1  wherein: 
 the spectral beam combiner assembly further includes a folding mirror for directing the thermal image from the thermal image sight assembly to the reflector for the reflector to reflect to the exit pupil.    
   
   
       3 . The aiming sight of  claim 1  wherein: 
 the thermal image sight assembly includes a thermal imager, a liquid crystal display (LCD) illuminated by a narrow-band light emitting diode (LED), and a long eye relief eyepiece;    wherein the thermal imager generates the thermal image of the target scene, wherein the LCD displays the thermal image as a monochromic image, and wherein the long eye relief eyepiece provides the thermal image displayed by the LCD to the reflector.    
   
   
       4 . The aiming sight of  claim 3  wherein: 
 optical power of the thermal imager and size of the LCD are selected to match magnification power of the objective lens of the magnified optical sight such that a size of the intermediate image plane of the magnified optical sight and a size of the LCD are the same.    
   
   
       5 . The aiming sight of  claim 3  wherein: 
 the thermal imager includes the LED that illuminates the LCD to display the thermal image as the monochromic image, wherein brightness of the LED is controllable in order to match brightness of the thermal image with brightness of the intermediate image such that the combined image has an even brightness.    
   
   
       6 . The aiming sight of  claim 3  wherein: 
 the thermal imager is controllable in order to generate the thermal image such that the thermal image includes targets in the target scene which have a temperature falling within a given temperature range and excludes all other targets in the target scene.    
   
   
       7 . The aiming sight of  claim 1  wherein: 
 the magnified optical sight includes a Pechan prism interposed between the objective lens and the reticle.    
   
   
       8 . The aiming sight of  claim 1  further comprising: 
 a night-vision scope positioned at the exit pupil, wherein the night-vision scope light-intensifies the combined image for night-time use of the aiming sight.    
   
   
       9 . The aiming sight of  claim 1  wherein: 
 the thermal image sight assembly is controllable to be turned-off such that the intermediate image provided from the magnified optical sight is passed to the exit pupil without a thermal image superimposed therein when the thermal image sight assembly is turned-off.