Okuma Corporation

Shuzo Hattori

Keiji Matsui

An optical position-detecting apparatus includes an optical block capable of causing interference light having interference fringes perpendicular to a diffraction grating on a subject of measurement to be all the time projected onto the diffraction grating. The apparatus detects the position of a subject of measurement by receiving either light transmitted through a diffraction grating on said subject of measurement or light reflected from said diffraction grating. The apparatus includes an optical block for causing collimated rays generated from a coherent light source to be diffracted, for causing only the '.+-.1' order diffracted light to be extracted and to interfere with each other, and for causing an interference light field area having interference fringes perpendicular to said diffraction grating to be generated and to be projected onto said diffraction grating. Thus, it is possible, with a simple construction, to assure stable outputting of a displacement signal.

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Niwa, Japan

Shuzo Hattori