Gun sight compensator

Abstract

A range compensator for a gun sight for an associated gun is provided. The compensator includes at least one Risley prism pair that is rotatable in opposite relative directions about a common axis; mounting means for mounting the Risley prism pair to the sight between the sight and a target at a distance; and, a respective rotator associated with the Risley prism pair for rotating each prism in the Risley prism pair about the axis that is generally aligned with the path. The prisms are rotatable between an unrefracted range finding position in which a “line of departure” required to ensure the projectile strikes the target is determined and a refracted firing position in which the path of light extending between the sight and the target is refractively deviated to maintain the target centered with the sight when the gun is positioned along the required “line of departure”.

1 . A range compensator for a gun sight which enables said gun sight to appear “on target” when an associated gun is deviated from “line of sight” orientation with said target to allow for trajectory characteristics of a projectile to be launched from said gun, said compensator comprising: 
 at least one Risley prism pair;    mounting means for mounting said Risley prism pair to at least one of the gun and the sight between said sight and said target to allow refractive deviation of a path of light extending between said sight and said target;    at least one respective rotator associated with each said Risley prism pair for rotating each prism in said Risley prism pair in at least opposite relative directions about an axis generally aligned with said path to cause said refractive deviation;    a processor;    a range finder communicating with said processor for determining the distance to said target of said gun and informing said processor of said distance;    trajectory information retrieval and storage means communicating with said processor for providing information concerning said trajectory characteristics to said processor;    said processor comparing said trajectory characteristics with said distance and determining a prism shift based thereon;    said prism shift corresponding to an amount of refraction which will cause said sight to view a location relative to said target where said projectile would be expected to strike at said distance were said gun pointed directly at said target whereby moving said gun to align said sight with said target will cause said gun to be positioned to correct for said trajectory characteristics;    said processor sending a signal to a respecting controller operably connected to each said rotator to effect rotational shift of said Risley prism pair corresponding to said amount of refraction.    
   
   
       2 . The range compensator of  claim 1  wherein: 
 said processor includes input means for wind speed;    said trajectory characteristics include windage and drop characteristics; and    said prism shift accommodates both windage and drop.    
   
   
       3 . The range compensator of  claim 2  wherein: 
 said at least one Risley prism pair includes a first Risley prism pair for windage compensation and a second Risley prism pair for drop compensation;    each said prism in each said first and second Risley prism pairs are counter-rotated by said respective rotator in effecting said rotational shift.    
   
   
       4 . The range compensator of  claim 3  wherein: 
 each said respective rotator is a motor rotationally coupled to each said prism in said Risley prism pair to cause equal but opposite rotation of said prisms about said axis upon activation of said motor.    
   
   
       5 . The range compensator of  claim 2  having one said Risley prism pair and wherein said rotator effects said rotational shift by a combination of co-rotation and counter-rotation of said Risley prism pair.  
   
   
       6 . The range compensator of  claim 5  wherein: 
 said rotator includes first and second motors,    said first motor is rotationally coupled to both prisms in said Risley prism pair to cause equal but directionally opposite rotation of said prisms about said axis in response to actuation of said first motor; and,    said second motor is rotationally coupled to both said prisms to cause simultaneous and equal co-rotation of said prisms in response to activation of said second motor.    
   
   
       7 . The range compensator of claims  1 ,  2 ,  3 ,  4 ,  5  or  6  wherein said gun sight is a laser sight and said at least one Risley prism pair refracts a laser beam emanating from said laser sight.  
   
   
       8 . The range compensation of claims  1 ,  2 ,  3 ,  4 ,  5  or  6  wherein said gun sight is a telescopic sight.  
   
   
       9 . A range compensator for a gun sight having an associated gun positionable for launching a projectile along a “line of departure” comprising: 
 at least one Risley prism pair, the prisms being rotatable in at least opposite relative directions about a common axis;    mounting means for mounting the Risley prism pair to at least one of the gun and the sight between the sight and a target at a distance for allowing refractive deviation of a path of light extending between the sight and the target;    at least one respective rotator associated with each Risley prism pair for rotating each prism in the Risley prism pair about the axis, the axis being generally aligned with the path, the prisms being rotatable between an unrefracted range finding position in which the “line of departure” required to ensure the projectile strikes the target is determined and a refracted firing position in which the path of light extending between the sight and the target is refractively deviated to maintain the target centered with the sight when the gun is positioned along the required “line of departure”; and,    indication means for determining the degree of refractive deviation.    
   
   
       10 . The range compensator of  claim 9  further comprising: 
 a range finder for determining the target distance;    a prism rotation retrieval and storage means, the prism rotation retrieval and storage means for providing the degree of prism pair rotation required for rotating the prisms of the Risley prism pair to the refracted firing position and communicating the required degree of prism pair rotation to an operator;    a respective controller operable by the operator and connected to each respective rotator to effect rotation of the Risley prism pair by the require degree of rotation.