| 摘要 |
PURPOSE:To obtain a length measuring apparatus for resolving capacity in the order of submicron, by installing a light-resolving element, collimator lens, interference optical system and a detecting element counting optically a number of displaced lines of the interference fringes. CONSTITUTION:A flux of light from a laser L is made to parallel beams by a collimator lens C1, passed through a half-mirror HM1 and resolved into the reference beams reflected by the half-mirror HM1 and passing beams to be measured. The passing beams are collected onto a mirror surface reflecting body M by a collimator lens C2. The reflected beams are collected by the lens C2 and reflected by the HM1 and the collected beams, together with the reference beams reflected likewise by the half-mirror HM1, pass through an opening S, and generate interference fringes on the photoelectric element P. Displacements of the interference fringes by that of the mirror M are counted by a counter C. |
