DIMENSION MEASURING DEVICE USING DIFFRACTED LIGHT INTERFERENCE OF DIFFRACTION GRATING

摘要

PROBLEM TO BE SOLVED: To reduce the size and cost of an optical system while precision and reliability in dimension measurement is improved by constituting the optical system so that a single one-phase signal where the light intensity changes in sine wave is generated. ;SOLUTION: Related to the optical system for the dimension measuring device, the laser beam from a laser beam source 10 is split into two directions by a beam splitter 11, so that a point P1 and point P2 of a diffraction grating 12 are irradiated in two directions, generating + primary diffracted light 120 and - primary diffracted light 125. They are made incident on a light-receiver 13 for interference to generate a single one-phase signal 14. The one-phase signal 14 comprises a waveform 140 wherein the intensity of interference light changes in sine wave according to the movement of the diffraction grating 12, and the intensity of sine wave changes one cycle for a half-pitch movement of the diffraction grating 12. The laser beam source 10 illuminates continuously and the waveform 140 is a signal being continuous in time. A signal processing part 100 processes data of the one-phase signal 14 for measuring a dimension.;COPYRIGHT: (C)2000,JPO