Method of aligning optical system using a hologram and apparatus therefor

Abstract

A method of aligning an optical system and an optical system incorporating the method. A hologram element is installed in the optical system so that test beams diffracted by the hologram element travel along a same optical path as test beams incident on the optical system. Alignment errors in the optical system are measured using interference patterns formed on an image surface by test beams returned from the optical system and reference beams. At least one optical element of the system is aligned using measurements calculated from the interference patterns. The optical system may provide for temporarily installing the hologram element to perform the measurements or the optical system may be constructed with a hologram formed on any optical element which may require alignment. A direction and a magnitude of any misalignment are determinable based on an appearance of the pattern and a number of circles in the pattern, respectively.

1 . An optical system comprising at least one optical element having a hologram for diffracting light beams on a same optical path as light beams transmitted or reflected by the at least one optical element.  
   
   
       2 . The optical system of  claim 1 , wherein the hologram is a computer-generated hologram.  
   
   
       3 . An optical system comprising: 
 a barrel; and    at least one optical element having a hologram element formed thereon,    wherein: 
 the at least one optical element is placed in a predetermined position of the barrel so that test beams diffracted by the hologram element travel along a same optical path as test beams incident on the optical system.  
   
   
   
       4 . The optical system of  claim 3 , wherein the hologram element is a computer-generated hologram element.  
   
   
       5 . An optical system comprising: 
 a barrel; and    at least one optical element mounted in the barrel,    wherein: 
 the barrel further comprises a unit in which to place a hologram element in a predetermined position of the barrel.  
   
   
   
       6 . The optical system of  claim 5 , wherein the hologram element enables measurement of a manufacturing condition of the barrel.  
   
   
       7 . The optical system of  claim 5 , wherein the hologram element assists in an alignment of the optical element.  
   
   
       8 . The optical system of  claim 5 , wherein the hologram element is a computer-generated hologram element.  
   
   
       9 . An optical system, comprising: 
 a barrel; and    at least one optical element mounted in the barrel, the at least one optical element having a computer generated hologram written on a peripheral area of the optical element.    
   
   
       10 . The optical system of  claim 9 , wherein the computer generated hologram is ring shaped.  
   
   
       11 . The optical system of  claim 9 , wherein the computer generated hologram is fan shaped.