| 摘要 |
<p>PURPOSE:To obtain a plurality of detecting regions for one Fresnel-lens surface by deflecting an optical axis for the detecting regions to a plurality of different angles. CONSTITUTION:Surface parts 11a and 11b of linear multiple prisms are fromed at the front surface of an optical member 11. The prism-surface parts 11a and 11b are symmetrical with respect to an optical axis O - O' and formed at the uniform same angle. One Fresnel-lens part 1c is formed at the rear surface of the member 11. A light emitting element 12 is arranged at the rear side of the member 11. The optical axis of the element 21 is perpendicular to the Fresnel-lens part 11c. In this constitution, the luminous flux from one light emitting element 12 is divided into the upper and lower parts through the prism- surface parts 11a and 11b after the luminous flux has passed through the Fresnel-lens part 11c. Thus, the luminous fluxes can be projected on detecting regions 13a and 13b.</p> |
