| 摘要 |
PROBLEM TO BE SOLVED: To improve the parallelism between the positional reference surface of a light receiving and emitting unit and that of a housing even when the light receiving and emitting unit is composed in a thin type. SOLUTION: The surface of the heat sink part 22 of the light receiving and emitting unit 20 is used as a first positional reference surface for positioning the light receiving and emitting unit 20 to a holder part 12, the end surface 12f in which the opening part of the holder part 12 of the housing 10 is provided is used as a second positional reference surface in the case of attaching the light receiving and emitting unit 20 to the inside of the holder part 12, and the first positional reference surface and the second positional reference surface are attached by butting them against a mount. Thus, respective areas of the first positional reference surface and the second positional reference surface are widely used and whereby parallelism between the light receiving and emitting unit 20 and the housing 10 is improved.
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