Apparatus and method for measuring variations in thickness of an optical interference element

摘要

In a system for measuring variations in thickness of an optical etalon, a light source and a diffraction grating are mounted on a base structure with an axle. A lever arm is affixed to the axle, and a micrometer is held in contact with the lever arm. The grating directs a into an optical path a wavelength of radiation dependent on orientation of the grating. The etalon is supported in the optical path to effect a fringe pattern representing variations in thickness of in the etalon. The orientation is varied with the micrometer so as to vary the wavelength to the etalon and thereby positioning of the fringe pattern across the etalon which is viewed through a microscope. The micrometer measures the variation of orientation and thereby variation in thickness across the interference element.