| 摘要 |
PURPOSE:To detect securely the distance between cars and their relative speed by arranging a laser light emission part within the focal length of a lens and expanding the beam diameter of a laser beam. CONSTITUTION:The laser light emission part 22 is arranged closer to the lens 21 than its focal length. The laser light from the light emission part 22 is increased in beam diameter toward a car 1 running ahead to obtain a laser beam 3, which is about as wide as one lane of a road at the maximum necessary detection distance of the laser radar device 2. Therefore, the beam 3 illuminates the whole of the car running ahead and its reflected light reaches the photodetecting element of the device 2 to detect securely the distance to the car and relative speed. |
