Experimental Studies of Edge Effect and Contrast in Phase Microscope. I

概要

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A phase microscope with the cross-shaped diffraction plate was constructed and the condenser diaphragm of the same type was made. We are able to change the clearance of condenser diaphragm uniformly and continuously, so we can use this diaphragm for various kinds of objectives. With this apparatus, we studied the edge effect and the contrast of the amplitude gratings with various structure constants, and we also made a special diffraction plate with eccentricity, and observed that the edge effect could reach the maximum value by the use of the plate with proper eccentricity. This special diffraction plate can be used effectively in the observation of samples with direction (for instance, fibres, scratches, track of particles, etc.). The results observed are as follows : (1) In the case of the diffraction plate with the absorption only, the contrast increases and gradually comes up to the constant as the transmittance grows. On the contrary, the larger the transmittance grows, the smaller the edge effect grows, and disappears at about the transmittance 50〜60%. (2) In the diffraction plate with the fixed absorption and retardation, the contrast changes by the width of conjugate area and by the structure constants. The larger the width grows, the larger edge effects grow, and those are same in all structure constants.
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