Measurement of Thermal Deformation by Interferometer Utilizing Optical Fiber

This paper describes a study of an interferometer utilizing an optical fiber for highly accurate measurement of thermal deformation of a mechanical part in out-of-plane direction. This interferometer utilizes a polarization-preserving optical fiber. Two signal lights pass the same optical paths of the fiber, and the influence of the external disturbance (for example, temperature changes) to the optical paths of the fiber can be cancelled by the differential detection of the interference signals of these lights. A reference plane is set near an object plane, and an optical probe with the reference plane is composed of the materials with small thermal expantion coefficient. The experiment verified that the present interferometer worked in the same way as the theory. The present interferometer was applied to a measurement of thermal expantion, and its measuring dispersion of this interferometer was within ±60 nm.