Simplified polanret system for microscopy.
A variable phase contrast and amplitude contrast device of the polanret type has been developed. It uses only a single polarizing ring, instead of three zonal polarizers as required in Osterberg's original polanret system, and is therefore much more easily manufactured, its economy of light is better, and its range of amplitude contrast is improved. However, it also requires an easily accessible microscope objective exit pupil, where the polarizing ring must be located to cover the direct image of a conjugate annular diaphragm of a phase contrast condenser.
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