Projection system and optical path transfer device thereof

Abstract

A projection system. The projection system has a light source, a relay module, an optical path switching device and an optical path transfer device. The light source emits a light beam, and the relay module relays the light beam. The optical path switching device is used to receive and switch the light beam and has at least one active area. The optical path transfer device is disposed between the relay module and the optical path switching device directing the light beam toward the optical path switching device in a first angle, and the optical path transfer device has an incident surface tilted perpendicular to an incidence of the light beam.

1 . An optical path transfer device for guiding a light beam toward a light receiving device, the optical path transfer device comprising: 
 at least two parts for transferring the light beam, each comprising an incident surface; and    at least one air gap formed between the at least two parts;    wherein the incident surface tilts in a direction perpendicular to an incidence of the light beam.    
   
   
       2 . The optical path transfer device as claimed in  claim 1 , wherein the light beam is incident onto the light receiving device at a first angle.  
   
   
       3 . The optical path transfer device as claimed in  claim 2 , wherein the incident surface forms a second angle with a normal of each side surface of the at least two parts, variable corresponding to the first angle.  
   
   
       4 . The optical path transfer device as claimed in  claim 1 , wherein the light receiving device comprises an optical path switching device for receiving or switching the light beam.  
   
   
       5 . The optical path transfer device as claimed in  claim 4 , wherein the optical path switching device comprises a digital micromirror device (DMD) or a liquid crystal on silicon (LCoS).  
   
   
       6 . The optical path transfer device as claimed in  claim 1 , wherein the at least two parts are prisms, glass, or a photoconductive material with a refractive index larger than  1 .  
   
   
       7 . The optical path transfer device as claimed in  claim 1 , wherein an illumination area of the light beam projected on the light receiving device from the optical path transfer device is similar to the active area in s size and shape.  
   
   
       8 . The projection system as claimed in  claim 1 , wherein the optical path transfer device is a total internal reflection prism (TIR prism) or a reversed total internal reflection prism (reversed TIR prism).