Method and apparatus for making a high resolution light pattern generator on a transparent substrate

Abstract

A light pattern generator that can be used to form a gobo for use in a projection optical system. A transparent plate is coated with a stack that is absorptive and reflective. The stack is formed to be ablatable in the form of a pattern. The stack can have multiple different layers with multiple different characteristics, all of which are ablated by the laser.

What is claimed is: 
     
         1 . A method comprising: forming an optical structure comprising a transparent plate with front and rear sides, and having a coating stack bonded to one of said sides of the transparent plate, said coating stack comprising: a release layer that is an ultraviolet absorber that is vaporized by application of ultraviolet radiation, a dark coating which absorbs ultraviolet; and a reflector layer, coupled to said dark coating;
 Processing said optical structure by using a UV laser that passes through said transparent plate to said coating stack, to vaporize said release layer and ablate a portion of said dark coating adjacent to a location of vaporizing said release layer.   
     
     
         2 . A method as in  claim 1 , further comprising producing a light beam through said optical structure after said processing, to shape said light beam. 
     
     
         3 . A method as in  claim 1 , wherein said reflector layer has multiple layers of reflector material. 
     
     
         4 . The method as in  claim 1 , wherein said processing forms a shape in said coating stack which changes a shape of said light beam. 
     
     
         5 . A method as in  claim 1 , wherein said forming further comprising using an anti-reflection coating on the front side of the transparent plate, said coating being substantially transmissive to radiation. 
     
     
         6 . A method as in  claim 5 , wherein said coating stack is on said rear side of said transparent plate. 
     
     
         7 . A method as in  claim 1 , wherein said coating stack is on said front side of said transparent plate. 
     
     
         8 . A method comprising:
 directing a UV laser through an optical structure formed of a transparent plate with front and rear sides and which has a coating stack bonded to the rear side of the transparent plate, said coating stack comprising:
 a first layer which is vaporized by UV radiation; 
 a second layer substantially absorptive to radiation in a second range; and 
 a third layer substantially reflective to radiation in a third range; and 
 using said UV laser to vaporize areas of said first layer and ablate portions of said second layer and third layer which are adjacent to said areas of said first layer. 
   
     
     
         9 . A method as in  claim 8 , wherein said second range and said third range are the same. 
     
     
         10 . A method as in  claim 8 , further comprising producing a light beam through said optical structure after said using, to shape said light beam. 
     
     
         11 . A method as in  claim 10 , wherein said directing forms a shape in said coating stack which changes a shape of said light beam. 
     
     
         12 . A method as in  claim 8 , further comprising using an anti-reflection coating on the front side of the transparent plate, said coating being substantially transmissive to radiation.