Erector cam

Abstract

Provided herein is technology relating to telescopic optics and particularly, but not exclusively, to devices and methods for moving a lens in a variable power optical device zoom system.

1 - 18 . (canceled) 
     
     
         19 . An optical device zoom system comprising:
 n movable lens cells;   f followers per each movable lens cell; and   a rotating cam tube comprising N helical tracks,   wherein:
     N=n×f;    
   n≥2; and   f≥2.   
     
     
         20 . The optical device zoom system of  claim 19 , wherein a movable lens cell comprises f followers arranged around the circumference of the movable lens cell at an interval of (360°/f). 
     
     
         21 . The optical device zoom system of  claim 19 , wherein said rotating cam tube comprises f helical tracks for a movable lens cell arranged around the circumference of the cam tube at an interval of (360°/f). 
     
     
         22 . The optical device zoom system of  claim 19 , wherein f=2. 
     
     
         23 . The optical device zoom system of  claim 19 , wherein n=2. 
     
     
         24 . The optical device zoom system of  claim 19 , wherein n≥3. 
     
     
         25 . The optical device zoom system of  claim 19 , wherein the optical device is a riflescope. 
     
     
         26 . The optical device zoom system of  claim 19 , wherein a helical track has a constant pitch over its length. 
     
     
         27 . The optical device zoom system of  claim 19 , wherein a helical track has a varying pitch over its length. 
     
     
         28 . An optical device zoom system comprising:
 a plurality of n movable lens cells; and   a rotating cam tube comprising N helical tracks,   wherein:   the ith movable lens cell comprises f i  followers; and
     N=Σ   i=1   n   f   i . 
   
     
     
         29 . The optical device zoom system of  claim 28 , wherein n≥2 and f 1 ≥2 and f 2 ≥2. 
     
     
         30 . The optical device zoom system of  claim 28 , wherein n≥3. 
     
     
         31 . The optical device zoom system of  claim 28 , wherein a helical track has a varying pitch over its length. 
     
     
         32 . The optical device zoom system of  claim 28 , wherein a helical track has a constant pitch over its length. 
     
     
         33 . A method for adjusting zoom of an optical device, said method comprising:
 providing an optical device zoom system comprising:
 a plurality of n movable lens cells; and 
 a rotating cam tube comprising N helical tracks, 
 wherein: 
 the ith movable lens cell comprises f i  followers; and
     N=Σ   i=1   n   f   1 ; and 
 
   rotating said cam tube to move said movable lens cells linearly along an optical axis of said optical device.   
     
     
         34 . The method of  claim 33 , wherein n≥2 and f 1 ≥2 and f 2 ≥2. 
     
     
         35 . The method of  claim 33 , wherein n≥3. 
     
     
         36 . The method of  claim 33 , wherein rotating said cam tube moves said movable lens cells with minimal or no lens tilt with respect to said optical axis of the optical device. 
     
     
         37 . The method of  claim 33 , wherein a helical track has a varying pitch over its length.