A New Method of Light Microscopy

Abstract

THE method described by Prof. A. Wilska¹ appears to be a special case of phase-contrast, generally known as ‘amplitude-contrast’. Although not usually employed with fixed phase-contrast objectives, it frequently crops up in variable phase-contrast and interference systems. Oettlé², for example, used it in his experiments with a variable amplitude and phase microscope. The basic theory can be simply explained by a vector treatment similar to that given in detail elsewhere³. Object details can be represented by points in or on the well-known vector circle, centre O, radius OM. In conventional microscopy, the origin remains at Oand transparent phase-changing details such as P, which lie on the circumference of the circle, are all equidistant from O and appear with equal intensity, OP² (= OM²), so that contrast is zero.