| 摘要 |
The overall length of a lens, particularly the thickness thereof, is reduced to thereby reduce the volumetric capacity occupied by a lens system for distance measurement. A distance measuring apparatus has a light-emitting device; a light-projecting lens system for projecting light emitted from the light-emitting device onto a subject; a light-receiving lens system for receiving and converging reflected light from the subject; and a detector for detecting the light. The light-projecting lens system or the light-receiving lens system includes a diffractive optical element having plane surfaces r1 and r4 on both sides thereof, at least one of which is formed from a diffraction surface. A similar diffractive optical element is provided in a similar lens system adapted to change a projected light angle by adding a converter lens to a master lens, and also provided in a similar lens system adapted to change a projected light angle by changing the spacing between a plurality of lens units.
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