Abstract:
An adjustment mechanism for an optical system is provided. Two concentric eccentric rings support a back end of an optical element. The movements of the two rings relative to each other re-position the back end to affect the orientation of the field of view of the optical element. A clamp ring is provided to fix the position of the back end after the adjustment is completed.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention generally relates a pointing or aiming mechanism for optical elements, such as laser pointers, binoculars, telescopes, microscopes, etc. 
       BACKGROUND OF THE INVENTION 
       [0002]    Optical elements, such as lenses and pointers, mounted within rigid structures, such as gimbals, telescopes, reconnaissance scopes, or the likes, need to have their aiming mechanisms adjusted from time to time. Conventional adjustment devices are disclosed in U.S. Pat. Nos. 2,946,126, 4,497,548 and 5,433,010, among others. One conventional adjustment system disclosed in “Introduction to Opto-Mechanical Design” by Daniel Vukobratovich presented at the 1986 Tufts/SPIE Engineering Update Series in Electro-Optics in Tucson, Ariz., uses two coaxial eccentric rings surrounding an optical lens at the front of optical elements to adjust the position of the lens in two directions, i.e., up-down and side-to-side. However, in applications where space available for the optics is limited, having the positioning or adjustment system at the front end is impractical. 
         [0003]    Hence, the remains a need in the art for using adjustment systems, such as coaxial eccentric rings, at locations away from the lenses or the front end of the optical elements. 
       SUMMARY OF THE INVENTION 
       [0004]    Hence, the invention is directed to an adjustment mechanism for an optical system. The adjustment mechanism comprises two concentric eccentric rings supporting a back end of an optical element. The movements of the two rings relative to each other re-position the back end to affect the orientation of the field of view of the optical element. A clamp ring is provided to fix the position of the back end after the adjustment is completed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views: 
           [0006]      FIG. 1  is a cross-sectional view of an embodiment of an inventive optical pointing mechanism; 
           [0007]      FIG. 2A  is a perspective rear view and  FIG. 2B  is a perspective front view of the mechanism shown in  FIG. 1 ; and 
           [0008]      FIG. 3  is a schematic rear view of the adjustment mechanism according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0009]    Referring to  FIGS. 1 ,  2 A and  2 B, optical system or device  10  includes an optical element  12 , such as a laser pointer, reconnaissance scope, binocular, telescope or microscopes, is positioned within a housing  14 . Front end  16  of optical element  12  is supported for rotational movement by joint  18 . Examples of suitable joint  18  include, but are not limited to a spherical interface, a ball-and-socket joint or a shoulder joint. Back end  20  of optical element  12  is supported by an adjustment mechanism comprising an inner eccentric ring  22  and an outer eccentric ring  24 . Both eccentric rings are positioned within clamp ring  26 . 
         [0010]    Rotating inner ring  22  along arrow A and/or rotating outer ring  24  along arrow B move back end  20  in the X-Y plane shown in  FIG. 3 , and in turn move field of view (FOV)  28  to the desired direction. The operation of the adjustment mechanism is illustrated in  FIG. 3 . In one example, rotating inner ring  22  about half a revolution along arrow A while holding outer ring  24  stationary would move back end  20  in the X+ direction, i.e., to the right, and the thickest portions of both rings would be adjacent to each other on the left side. This X+ movement of back end  20  moves FOV  28  in the X− direction, i.e., to the left. Rotating outer ring  24  half a revolution along arrow B while holding inner ring  22  stationary would move back end  20  in the X− direction, i.e., to the left, and the thickest portions of both rings would be adjacent to each other on the right side. This X− movement of back end  20  moves FOV  28  in the X+ direction. 
         [0011]    Similarly, when both rings are rotated so that their thickest portions are located on top in reference to  FIG. 3 , back end  20  would move downward in the Y− direction and FOV  28  would move upward in the Y+ direction. Likewise, when both rings are rotated so that their thickest portions are located on the bottom in reference to  FIG. 3 , back end  20  would move upward in the Y+ direction and FOV  28  would move downward in the Y− direction. Moreover, the thickest (or thinnest) portions of both rings can be positioned at any angular position in the X-Y plane unaligned to either the X-axis or the Y-axis to point FOV  28  in any desirable direction. Additionally, the thickest (or thinnest) portions of both rings don&#39;t have to be positioned adjacent to each other. The alignment of the thickest (or thinnest) portions relative to each other affects the amount of displacement of back end  20  and FOV  28  on the X-Y plane. 
         [0012]    Preferably, back end  20  is loose within inner ring  22 . With the clamp ring  26  loosened, inner ring  22  becomes unloaded relative to back end  20 , reducing any friction forces between the inner ring and the back end, allowing one to be positioned relative to the other. Ideally, clamp ring  26  is loosened just enough to allow inner ring  22  to slide on or relative to back end  20  without losing contact. After the FOV  28  is aligned to the correct orientation, clamp ring  26  is tightened, which increases a normal force imparted by inner ring  22  on back end  20 . That normal force causes sufficient friction between inner ring  22  and back end  20  to prevent any further relative motion, thereby holding the orientation of back end  20 . 
         [0013]    Another parameter that can control the angle or cone of rotation of FOV  28  is the distance Z between joint  18  and inner/outer concentric rings  22  and  24 . Since optical element  12  is substantially pivoted at joint  18  and moved at back end  20 , shorter distance Z allows the cone of rotation to be larger and longer distance Z minimizes the size of the cone of rotation about pivot/joint  18 . 
         [0014]    Clamp ring  26  is provided to maintain the position of back end  20 . When clamp ring  26  is tightened, e.g., by rotating in the clockwise direction, movements of rings  22  and  24  are prohibited to lock in the position of back end  20  and FOV  28 . When clamp ring is loosened, e.g., by rotating in the counter-clockwise direction, movements of rings  22  and  24  are allowed to adjust the position of back end  20  and FOV  28 . 
         [0015]    Advantages of the present invention over the prior art include, but are not limited to, situations where space inside housing  14  is limited. One application is military reconnaissance equipment such as visual or IR scopes, where the housing needs to be small, lightweight and compact. An operator can adjust FOV  28  by manipulating clamp ring  26  and eccentric rings  22  and  24 , which are conveniently located near the operator&#39;s hands and eyes to minimize the movements of the operator&#39;s hands. Another application for the inventive adjustment mechanism is for optical elements mounted to rotating gimbals. In most gimbals, the front ends of the optical elements when installed on the outer housing of the gimbals generally cannot be moved translationally; however, the back ends can be moved rotationally. The inventive adjustment mechanism can be used in such situation to adjust the FOV of the optical elements. 
         [0016]    While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention.