| 摘要 |
An optical displacement sensor comprises a surface emitting laser light source, a scale and a photosensor. The surface emitting laser light source emits a light beam having a predetermined shape. The scale is displaceable in such a manner as to cross the light beam emitted from the surface emitting laser light source and has a diffraction grating of a predetermined period formed thereon for forming a diffraction interference pattern from the light beam. The photosensor receives a predetermined portion of the diffraction interference pattern. The photosensor includes light intensity detecting means comprised of a plurality of light receiving areas arranged apart from one another in a pitch direction of the diffraction interference pattern on a light receiving surface at intervals of np 1 (z 1 +z 2 )/z 1 where z 1 is a distance between a light-beam emitting surface of the surface emitting laser light source and a surface on which the diffraction grating is formed, z 2 is a distance between the surface on which the diffraction grating is formed and the light receiving surface of the photosensor, p 1 is the pitch of the diffraction grating on the scale, and n is a natural number.
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