Compact folded signal transmission and image viewing pathway design and visual display technique for laser rangefinding instruments

Abstract

A compact folded signal transmission and image viewing pathway design and visual display technique for laser rangefinding instruments incorporates a beam splitting cube in the eyepiece optical space and advantageously provides an objective image focal length substantially twice that of the physical length of the instrument optical components. Through the use of some of the same optical elements in both the image viewing pathway as well as the laser transmission pathway, a relatively long transmission focal length is provided which saves in both physical instrument space and component cost while also allowing for the use of reasonably sized photodiodes with improved power output over that of previous designs.

What is claimed is:  
     
         1 . A laser rangefinder comprising:
 a laser energy emitting device;   a laser emitting aperture in said laser rangefinder; and   a laser transmission pathway in said rangefinder for redirecting a laser beam from said laser emitting device through effectively 90° to said laser emitting aperture.   
     
     
         2 . The laser rangefinder of  claim 1  wherein said 90° redirection of said laser beam is effectuated by five 90° redirections of said laser beam. 
     
     
         3 . The laser rangefinder of  claim 2  wherein at least a portion of said five 90° redirections of said laser beam are effectuated by mirrored surfaces. 
     
     
         4 . The laser rangefinder of  claim 3  wherein said mirrored surfaces comprise first, second and third mirrored surfaces. 
     
     
         5 . The laser rangefinder of  claim 4  further comprising:
 an image viewing pathway wherein an image of a target towards which said laser beam is directed is reflected by at least said first, second and third mirrored surfaces. 
 
     
     
         6 . The laser rangefinder of  claim 2  wherein at least a portion of said five 90° redirections of said laser beam are effectuated by at least one prism. 
     
     
         7 . A laser rangefinder comprising:
 a laser transmission pathway for directing laser energy toward a target;   a laser reception pathway for receiving at least a portion of said laser energy reflected from said target;   an image viewing pathway for providing an image of said target to an eyepiece of said rangefinder; and   a visual display device disposed in at least one of two image planes viewable through said eyepiece, said image viewing pathway comprising a beam splitting cube providing said image of said target and said visual display to said eyepiece.   
     
     
         8 . The laser rangefinder of  claim 7  wherein said beam splitting cube is disposed proximate to said eyepiece in said image viewing pathway. 
     
     
         9 . The laser rangefinder of  claim 7  wherein said visual display is disposed in an image plane at 90° to a portion of said image viewing pathway directly through said beam splitting cube. 
     
     
         10 . The laser rangefinder of  claim 9  wherein said visual display is disposed adjacent to said beam splitting cube. 
     
     
         11 . The laser rangefinder of  claim 9  wherein said visual display comprises an illuminated aiming reticule. 
     
     
         12 . The laser rangefinder of  claim 9  wherein said visual display one of a back-lit LCD display or LED display 
     
     
         13 . The laser rangefinder of  claim 7  wherein said visual display is disposed in an image plane along said image viewing pathway. 
     
     
         14 . The laser rangefinder of  claim 13  wherein said visual display is disposed adjacent to said beam splitting cube. 
     
     
         15 . The laser rangefinder of  claim 13  wherein said visual display comprises one of an LCD shutter display, LCD transmissive display or P-OLED display. 
     
     
         16 . The laser rangefinder of  claim 7  further comprising an adjustable contrast element in said image viewing pathway. 
     
     
         17 . The laser rangefinder of  claim 16  wherein said adjustable contrast element comprises photochromic glass in conjunction with a light source. 
     
     
         18 . The laser rangefinder of  claim 17  wherein said light source comprises a UV LED. 
     
     
         19 . The laser rangefinder of  claim 7  wherein said visual display devices comprise first and second visual display devices, said first visual display device being disposed in a first image plane at 90° to a portion of said image viewing pathway directly through said beam splitting cube and said second visual display device being disposed in a second image plane along said image viewing pathway. 
     
     
         20 . A laser rangefinder including an image viewing pathway comprising:
 an adjustable contrast element in said image pathway.   
     
     
         21 . The laser rangefinder of  claim 20  wherein said adjustable contrast element comprises a photochromic element. 
     
     
         22 . The laser rangefinder of  claim 21  further comprising:
 a light source associated with said photochromic element. 
 
     
     
         23 . The laser rangefinder of  claim 22  wherein said light source is an ultraviolet light source. 
     
     
         24 . The laser rangefinder of  claim 22  wherein the intensity of said light source is adjustable. 
     
     
         25 . The laser rangefinder of  claim 24  wherein said intensity of said light source is adjustable by a user of said laser rangefinder. 
     
     
         26 . The laser rangefinder of  claim 22  wherein said intensity of said light source is automatically adjustable in response to ambient illumination in said image pathway. 
     
     
         27 . The laser rangefinder of  claim 20  further comprising a beam splitting cube interposed between said adjustable contrast element and an eyepiece of said laser rangefinder. 
     
     
         28 . The laser rangefinder of  claim 27  further comprising:
 a light source orthogonally disposed to said beam splitting cube. 
 
     
     
         29 . The laser rangefinder of  claim 28  wherein said light source is an ultraviolet light source.