Differential interference contrast microscope and microscopic image processing system using the same

Abstract

A differential interference contrast microscope including an illuminating light source 61 , a polarizer 62 for converting an illumination light ray into a linearly polarized light, a polarized light separating means 63 for dividing the linearly polarized light ray into two linearly polarized light rays having mutually orthogonal vibrating directions, an illuminating optical system 64, 65 for projecting the two linearly polarized light rays onto an object 66 under inspection, a polarized light combining means 69 for combining the two linearly polarized light rays on a same optical path via an inspecting optical system 67, 68 , an analyzer 70 for forming a differential interference contrast image on an imaging plane 71 . The polarized light separating means 63 is constructed such that an amount of wavefront shear between the two linearly polarized light rays on the object can be changed, and the polarized light combining means 69 is arranged between the object 66 and the analyzer 70 at such a position that the two linearly polarized light rays propagate in parallel with each other and is constructed such that the two linearly polarized light rays can be combined with each other in accordance with the shear amount of wavefront introduced by the polarized light separating means 63.

What is claimed is:  
     
         1 . A differential interference contrast microscope of transmission type comprising: 
 an illumination light source means for emitting an illumination light ray;    a first polarizing means for converting the illumination light ray emitted from the illumination light source means into a linearly polarized light ray;    a polarized light separating means for separating the linearly polarized light ray emanating from the first polarizing means into two linearly polarized light rays having mutually orthogonal vibrating directions;    an illuminating optical system including a condenser lens and introducing said two linearly polarized light rays having mutually orthogonal vibrating directions onto an object under inspection;    an inspecting optical system including an objective lens and inspecting the object under inspection;    a polarized light combining means for combining said two linearly polarized light rays transmitted through the object under inspection on a same optical axis; and    a second polarizing means for interfering said two linearly polarized light rays combined on the same optical axis with each other to form an interference image;    wherein said polarized light separating means is constructed to change an amount of wavefront shear of the two linearly polarized light rays with mutually orthogonal vibrating directions on the object under inspection, and said polarized light combining means is arranged between said object under inspection and said second polarizing means at such a position that said two linearly polarized light rays propagate in parallel with each other and are combined with each other on the same optical axis in accordance with a variable amount of wavefront shear introduced by said polarized light separating means.    
     
     
         2 . A microscope according to    claim 1   , wherein said inspecting optical system comprises a first lens group including said objective lens and a second lens group including an imaging lens, said first and second lens groups being arranged such that a back focal point of the first lens group is identical with a front focal point of the second lens group, and said polarized light combining means is arranged behind the second lens group.  
     
     
         3 . A microscope according to    claim 1    or    2   , wherein said polarized light separating means is constructed to separate the linearly polarized light ray into the two linearly polarized light rays having mutually orthogonal vibrating directions and is arranged at such a position that said two linearly polarized light rays having mutually orthogonal vibrating directions are made incident upon said object under inspection substantially in parallel with each other and that an amount of wavefront shear is changed in cooperation with said polarized light combining means.  
     
     
         4 . A microscope according to    claim 3   , wherein said illuminating optical system comprises a third lens group and a fourth lens group, said third and fourth lens groups being arranged such that a back focal point of the third lens group is identical with a front focal point of the fourth lens group, and said polarized light separating means is arranged in front of said third lens group.  
     
     
         5 . A microscope according to    claim 3   , wherein said objective lens in the imaging optical system is constructed to be removably inserted into the optical axis and said illuminating optical system is constructed to change a focal length of the illuminating optical system in accordance with a back focal point of an objective lens to be inserted into the optical axis.  
     
     
         6 . A microscope according to    claim 1    or    2   , wherein said polarized light separating means is constructed to separate the linearly polarized light ray into the two linearly polarized light rays which have mutually orthogonal vibrating directions and propagate in parallel with each other and is arranged at such a position that said two linearly polarized light rays having mutually orthogonal vibrating directions are made incident upon said object under inspection substantially in parallel with each other and that an amount of wavefront shear is changed in cooperation with said polarized light combining means.  
     
     
         7 . A microscope according to    claim 6   , wherein said illuminating optical system comprises a third lens group and a fourth lens group, said third and fourth lens groups being arranged such that a back focal point of the third lens group is identical with a front focal point of the fourth lens group, and said polarized light separating means is arranged in front of said third lens group.  
     
     
         8 . A microscope according to    claim 6   , wherein said objective lens in the imaging optical system is constructed to be removably inserted into the optical axis and said illuminating optical system is constructed to change a focal length of the illuminating optical system in accordance with a back focal point of an objective lens to be inserted into the optical axis.  
     
     
         9 . A microscope according to    claim 1   , wherein said polarized light separating means includes a variable focus optical system arranged in said illuminating optical system and is contracted to change an amount of wavefront shear in cooperation with said polarized light combining means.  
     
     
         10 . A differential interference contrast microscope of transmission type comprising: 
 an illumination light source means for emitting an illumination light ray;    a first polarizing means for converting the illumination light ray emitted from the illumination light source means into a linearly polarized light ray;    an illuminating optical system including a condenser lens and illuminating an object under inspection with said linearly polarized light ray;    an inspecting optical system including an objective lens and inspecting the object under inspection;    a second polarizing means for interfering two linearly polarized light rays combined on a same optical axis with each other to form an interference image;    a polarized light separating and combining means for separating the linearly polarized light ray emanating from the first polarizing means into two linearly polarized light rays having mutually orthogonal vibrating directions and combining two linearly polarized light rays propagating in parallel with each other on a same optical axis; and    a reflection means for projecting said linearly polarized light ray emanating from said first polarizing means onto the object under inspection by means of said polarized light separating and combining means and illuminating optical system as said two linearly polarized light rays having mutually orthogonal vibrating directions and propagating in parallel with each other, and impinging the two linearly polarized light rays transmitted through the object under inspection, having mutually orthogonal vibrating directions and propagating in parallel with each other upon said polarized light separating and combining means by means of said imaging optical system.    
     
     
         11 . A microscope according to    claim 10   , wherein said linearly polarized light ray emanating from said first polarizing means is made incident upon a first portion of said polarized light separating and combining means and said two linearly polarized light rays having mutually orthogonal vibrating directions, propagating in parallel with each other and transmitted through the object under inspection is made incident upon a second portion of the polarized light separating and combining means, said second portion being different from said first portion.  
     
     
         12 . A microscope according to    claim 10    or    11   , wherein said objective lens in the imaging optical system is constructed to be removably inserted into the optical axis and said illuminating optical system is constructed to change a focal length of the illuminating optical system in accordance with a back focal point of an objective lens to be inserted into the optical axis.  
     
     
         13 . A differential interference contrast microscope of reflection type comprising: 
 an illumination light source means for emitting an illumination light ray;    a first polarizing means for converting the illumination light ray emitted from the illumination light source means into a linearly polarized light ray;    an imaging optical system including an objective lens for irradiating an object under inspection and inspecting the object under inspection;    a reflection member for introducing said linearly polarized light ray emanating from the first polarizing means into said imaging optical system;    a polarized light separating and combining means for separating the linearly polarized light ray emanating from the first polarizing means into two linearly polarized light rays having mutually orthogonal vibrating directions and combining the two linearly polarized light rays reflected by the object under inspection with other on a same optical axis; and    a second polarizing means for interfering the two linearly polarized light rays combined on a same optical axis with each other to form an interference image;    wherein said polarized light separating and combining means is constructed such that said linearly polarized light ray emanating from the first polarizing means into the two linearly polarized light rays having mutually orthogonal vibrating directions and propagating in parallel with each other and an amount of wavefront of said two linearly polarized light rays can be changed, and said polarized light separating and combining means is arranged at such a position that said two linearly polarized light rays with mutually orthogonal vibrating directions are made incident upon the object under inspection in parallel with each other.    
     
     
         14 . A microscope according to    claim 13   , wherein said imaging optical system comprises a first lens group including said objective lens and a second lens group including an imaging lens, said first and second lens groups being arranged such that a back focal point of the first lens group is identical with a front focal point of the second lens group, and said polarized light separating and combining means is arranged behind said second lens group.  
     
     
         15 . A microscopic image processing system comprising: 
 a differential interference contrast microscope, in which an object under inspection is irradiated with two linearly polarized light rays having mutually orthogonal vibrating directions and the two linearly polarized light rays transmitted through or reflected by the object under inspection are combined on a same optical axis to form a differential interference contrast image of the object under inspection on an imaging plane;    an electronic image sensing means for picking-up said differential interference contrast image of the object under inspection to derive an image signal; and    an image processing means for performing selectively a contrast enhancement for said image signal supplied from said electronic image sensing means;    wherein an amount of wavefront shear of said two linearly polarized light rays having mutually orthogonal vibrating directions on said object under inspection is changed in accordance with an image processing to be performed by said image processing means.    
     
     
         16 . A system according to    claim 15   , wherein said differential interference contrast microscope is formed by the microscope as claimed in    claim 1   .  
     
     
         17 . A microscopic image processing system comprising: 
 a differential interference contrast microscope, in which an object under inspection is irradiated with two linearly polarized light rays having mutually orthogonal vibrating directions and the two linearly polarized light rays transmitted through or reflected by the object under inspection are combined on a same optical axis to form a differential interference contrast image of the object under inspection on an imaging plane;    an electronic image sensing means for picking-up said differential interference contrast image of the object under inspection to derive an image signal; and    an image processing means for processing said image signal supplied from said electronic image sensing means to measure a phase difference or step structure of the object under inspection;    wherein an amount of wavefront shear of said two linearly polarized light rays having mutually orthogonal vibrating directions on said object under inspection is changed.    
     
     
         18 . A system according to    claim 17   , wherein said differential interference contrast microscope is formed by the microscope as claimed in    claim 1   .  
     
     
         19 . A microscopic image processing system comprising: 
 a differential interference contrast microscope of reflection type, in which an object under inspection is irradiated with two linearly polarized light rays having mutually orthogonal vibrating directions and the two linearly polarized light rays reflected by the object under inspection are combined on a same optical axis to form a differential interference contrast image of the object under inspection on an imaging plane;    an electronic image sensing means for picking-up said differential interference contrast image of the object under inspection to derive an image signal; and    an image processing means for processing said image signal supplied from said electronic image sensing means to detect a position of a depressed and protruded pattern of the object under inspection;    wherein an amount of wavefront shear of said two linearly polarized light rays having mutually orthogonal vibrating directions on said object under inspection is changed.    
     
     
         20 . A system according to    claim 19   , wherein said differential interference contrast microscope is formed by the microscope as claimed in    claim 13   .