OPTICAL RADAR.

摘要

The present invention aims at increasing the divergence angle of a beam in the direction of a road surface in a short-range with an omnidirectional detection zone and without sacrificing the maximum detectable range. A double-focus lens is integrally formed with a short focal distance portion provided in the central part thereof and with a long focal distance portion provided at the circumferential part thereof, and a light source is disposed at a distance from the double-focus lens which is slightly shorter than the focal distance of the short focal distance portion of the double-focus lens. When the light from the light source is projected through the double-focus lens, the outgoing light from the short focal distance portion thereof which has a small divergence angle does not diverge greatly, so that it can be sent far away. On the other hand, the outgoing light from the long focal distance portion which has a large divergence angle diverges a little, so that it is sent to a short distance area, especially, to an area extending in the width direction of a road surface. <IMAGE>