| 摘要 |
An interferometer for optically sensing displacements in a surface. Prior art interferometers use an air path to transmit the light from the source to the eventual interference target. Fluctuations in the ambient atmosphere due to local variations in temperature or pressure can introduce phase changes into the optical paths which are not the same for both the signal and the reference path. These fluctuations, which limit the ultimate sensitivity of the device, are minimized by utilizing fiber optics to direct the light within the interferometer. A first fiber optic waveguide (56) receives light from a laser (12) in one end and transports it to the other end (60) where a portion is back reflected and a portion is projected upon the surface (24). The reflected light from the surface (24) re-enters the fiber optic at the end (60) and combines with the back reflected signal to form an optical information wave. This optical information wave is evanescently coupled over a length, L, to a second fiber optic waveguide (58) which transports this wave to a detector (44). An absorber (66) is placed at one end of fiber optic waveguide (58) in order to eliminate end reflections in fiber optic waveguide (58). |
