A microscope-based interferometer with a variable wavelength illumination system

The paper demonstrates initial results of measuring the retardance of waveplates using a variable wavelength interferometer. The instrument utilizes a continuously variable interference bandpass filter placed in a specially designed intermediate image plane. The fringe field, created by the Wollaston prism, is processed and analysed only once, which speeds up the measuring procedure. In this application a reflected-light mode configuration is presented. The solution is suitable also for transmitted-light systems. The interferometer provides the user the spectral characteristic of retardance of the waveplate across the visible spectrum. The instrument is based on a classical microscope with the Kӧhler illumination system.