| 摘要 |
<p>There are provided slit arrays (SA1, SA2) comprising a plurality of reflection slits arranged side by side along a measurement axis and an optical module (130) capable of relatively moving on a measurement axis (C) while facing part of the slit arrays, wherein the optical module comprises a light source (131) that irradiates the slit array with light and light receiving arrays (PA1, PA2) comprising a plurality of light receiving elements arranged side by side along the measurement axis and arranged in positions offset with respect to the point light source in a width (R) direction perpendicular to the measurement axis in a plane parallel to the slit array, the light receiving elements being respectively receiving light irradiated from the point light source and reflected from the reflection slit, and the plurality of light receiving elements comprises respective shapes such that the light receiving element nearer to the point light source in the measurement axis direction comprises a shorter length in the width direction and end parts (En) on an opposite side of the light receiving elements (P0, P1, P2, P3, P4) with respect to the light source in the width direction are arranged side by side in positions along the measurement axis.</p> |
