Abstract: Provided is a polarization characteristic measuring method and apparatus for accurately measuring a polarization characteristic of fluorescence or Raman-scattered light emitted when a sample is exposed to light. The sample is exposed to excitation light radiated from a pulsed excitation light source and converted to p-polarized light by polarizer and half-wave plate, and photodetectors measure an intensity I.sub.pp of a p-polarized component and an intensity I.sub.ps of an s-polarized component of fluorescence emitted from the sample under irradiation with the excitation light. In similar fashion, the sample is exposed to the excitation light of s-polarized light and the detectors measure an intensity I.sub.sp of a p-polarized component and an intensity I.sub.ss of an s-polarized component of fluorescence emitted from the sample under irradiation. From these measured values, G factor is calculated according to the following equation:G=[(I.sub.pp .multidot.I.sub.sp)/(I.sub.ps .multidot.I.sub.ss)].sup.

Abstract: In an interferometer, reflected light from a reference surface and a subject surface are introduced to an imaging optical system through a beam splitter, and an interference fringe formed from light reflected from the both surfaces is observed with a detection optical system. An alignment optical member is disposed in an optical path between the imaging optical system and an image plane of the interference fringe such that the rear focal point of the alignment optical member is located at the image plane. The alignment optical member is inserted in the optical path in aligning the subject surface and is removed in measuring the interference fringe. Accurate alignment of the subject surface is easily attained. A beam expander is interposed between a polarizing beam splitter and the subject surface and a 90.degree. retarder is interposed between the beam expander and the subject surface. The 90.degree. retarder is constructed of one or a plurality of reflecting mirrors formed of dielectric multilayer films.

Abstract: An interferometer is used for observing the shape of a surface to be detected with the desired spatial resolution. A variable aperture stop is arranged at a Fourier transform image plane of the surface to be detected within an imaging optical system for forming an interference pattern of a reference light and a measuring light. The aperture diameter of the variable aperture stop is adjusted by a control in accordance with the desired spatial resolution.