TWO-BEAM INTERFERENCE TYPE LINEAR ENCODER

摘要

PURPOSE:To obtain the linear encoder which measures the length of a body, the depth of a hole, a movement distance, etc., with high accuracy by utilizing the principle of a two-beam interferometer, specially, a Mickelson interferometer. CONSTITUTION:The moving-side reflection system 14' of the two-beam interference type linear encoder 20A consists of reverse traveling reflectors, e.g. corner cubes 14B, 14C, and 14D and a plane mirror 14E. The reverse traveling reflectors 14B and 14D are arranged in a Y direction on a linearly movable rack 14A which is moved linearly by a driving mechanism while having their reflecting surfaces on the sides of while luminous flux and laser luminous flux which are split by a beam splitter 11. The fixed corner cube 14C and fixed plane mirror 14E are arranged in the Y direction outside the moving rack 14A and photodetect and reflect 2nd luminous flux which is reflected by those corner cubes 14B and 14D toward the corner cube 14D. Interference figures (a) and (b) are obtained by detectors 28 and 32. The interference figure (a) of the laser light can be utilized as an accurate scale for measuring a movement distance, etc.