An interferometer system for measuring distance changes between two structural components of a device

摘要

An interferometer system for measuring straightness including a light source for producing a beam of light, preferably a two frequency laser with the two frequency components linearly polarized and orthogonal to one another, the light beam being directed through a Wollaston prism where the beam is split into two separate paths which deviate, in opposite paths, from the original beam direction by a small angle. The two separate beams are transmitted over two separate paths to associated ones of two separate reflective surfaces which are mounted in a mutually fixed relationship and at an angle to each other. The two beams are reflected back into the prism from the associated reflective surfaces where they are recombined. Photodetector means are provided for detecting any changes in the fringes resulting from a change in one optical path length relative to other optical path length as the two mirrors move relative to the prism, said change in path lengths resulting from deviations from straightness in such movement. A dual system is disclosed for measuring rotational motion, i.e., roll.