Abstract Lack of uniformity in polarizing microscopes is caused by hyperbolae resulting in a cross-like distribution in the objective pupil of the instrument which results from rotation of the directions of polarization. A similar phenomena exists in differential interference contrast microscopes caused by small unwanted phase differences when the prisms are not perpendicularly traversed by the light. A birefringent compensating plate corrects the unwanted phase differences in selected areas of the field of a differential interference contrast microscope and, in combination with a quarter wavelength retardation plate, rotates the direction of polarization in selected areas of the objective pupil of a polarizing microscope to provide uniform pupil.
In a differential interference contrast microscope having at least one birefringent element, the improvement comprising a compensating plate comprising a birefringent material having an optic axis substantially parallel to the optical axis of the instrument, said compensating plate having a thickness effective to correct phase variations in the microscope field.
Claim 2
Dependent Claim
50 words
In a differential interference contrast microscope having at least one birefringent element, the improvement comprising a compensating plate comprising a birefringent material having an optic axis substantially parallel to the optical axis of the instrument, said compensating plate having a thickness effective to correct phase variations in the microscope field.
Claim 3
Dependent Claim
20 words
The improvement of claim 1 wherein the compensating plate is a magnesium fluoride crystal, wherein the birefringent material is quartz.
Claim 4
Dependent Claim
14 words
The improvement of claim 1 wherein the compensating plate is a magnesium fluoride crystal.
Claim 5
Dependent Claim
49 words
The improvement of claim 1 wherein said microscope is an incident light differential interference contrast microscope said birefringent element is quartz, having an actual thickness of 1.5 millimeters and said magnesium fluoride plate has a thickness of 0.9 millimeters to compensate for both light traversals of said birefringent element.
Claim 6
Dependent Claim
18 words
The combination of claim 4 wherein said birefringent element and compensating plate have the same incident light angle.