Optical Measurement System

Abstract

An optical system includes a collimated light source, a beam splitter, two mirrors and two lenses, a focus lens, and a detector. An initial light beam is generated by the light source and then separated by the beam splitter into a first light beam and a second light beam. The two mirrors respectively direct the first and second light beams on a sample with symmetrical paths and the two lenses focus the first and second light beam on the sample respectively. The first and second light beams are reflected from the sample and along the counterpart paths to the beam splitter. An interfered light beam is then generated by combining the reflected first and second light beams, and focused by a focus lens on a detector. A Dove prism can be configured between one mirror and one lens of the two for contrast enhancement. It can produce the photon combination with same of direction in this setup to enhance contrast.

What is claimed is: 
     
         1 . An optical system, comprising:
 a collimated light source for generating an initial light beam;   a beam splitter, receiving the initial light beam, for dividing the initial beam into two incident light beams symmetrical to a splitting plane of said beam splitter;   two mirrors and two lenses directing the two incident light beams being focused onto a surface of the sample respectively to generate an interference pattern on the surface, and receiving two reflected light beams from the sample back to said beam splitter, thereby generating an interfered light beam by combining the two reflected light beams at the beam splitter;   a focus lens for focusing the interfered light beam; and   a detector for receiving the focused interfered light beam to form an image.   
     
     
         2 . The optical system according to  claim 1 , wherein the splitting plane is normal to the surface. 
     
     
         3 . The optical system according to  claim 2 , further comprising a Dove prism for inverting one of the two incident light beams before being focused on the surface, and inverting the other of the two incident light beams after being focused on the surface. 
     
     
         4 . The optical system according to  claim 1 , wherein the light source is a low-coherent light source. 
     
     
         5 . The optical system according to  claim 1 , wherein the light source is a coherent light source. 
     
     
         6 . The optical system according to  claim 3 , wherein said collimated light source provides a white initial light beam, and further comprising:
 a dispersive optical element, receiving the interfered white light beam from said beam splitter, for dispersing the interfered white light into spectroscopic components;   a pinhole array for picking up the spectroscopic components into a plurality of interfered beams; and   a projection lens for projecting the plurality of interfered beams on said detector.   
     
     
         7 . The optical system according to  claim 3 , wherein said collimated light source provides a white initial light beam, and further comprising:
 a dispersive optical element, receiving the white light beam from said light source, for dispersing the white light into spectroscopic components;   a pinhole array for picking up the spectroscopic components into a plurality of beams; and   a beam block for picking a specific beam with a specific wavelength from the plurality of beams.   
     
     
         8 . The optical system according to  claim 3 , wherein said collimated light source provides a plurality of light beams with different wavelengths. 
     
     
         9 . The optical system according to  claim 3 , wherein two paths of the two incident light beams are symmetrical to the splitting plane. 
     
     
         10 . The optical system according to  claim 3 , further comprising a computer for processing information from said detector. 
     
     
         11 . The optical system according to  claim 3 , further comprising a first lens and a second lens for focusing the two incident light beams onto the surface of the sample.