The Principle and Application of Laser Distance Measuring Sensor
The laser ranging sensor uses a laser diode to aim at the target to emit laser pulses, and the laser light is scattered in all directions after being reflected by the target. Part of the scattered light returns to the sensor receiver, where it is captured by the optical system and imaged onto the avalanche photodiode. An avalanche photodiode is an optical sensor with internal amplification so that it can detect extremely faint light signals. The distance to the target can be determined by recording and processing the time elapsed from the time the light pulse is sent until it is received back.
Laser sensors must determine transit times extremely precisely because light travels so fast. To distinguish the time of 3ps, this is an exorbitant requirement for electronic technology, and the cost of implementation is too high. But today's laser sensors cleverly avoid this obstacle, using a simple statistical principle, that is, the average law to achieve a resolution of 1mm, and can guarantee the response speed.
The long-distance laser rangefinder emits a very thin laser beam to the target when it is working, and the photoelectric element receives the laser beam reflected by the target, and the timer measures the time from the launch to the reception of the laser beam, and calculates the distance from the observer to the target ; The LED white light speedometer is imaged on the internal integrated circuit chip CCD of the instrument. The CCD chip has stable performance, long working life, and is basically not affected by the working environment and temperature. Therefore, the measurement accuracy of the LED white light speedometer is guaranteed, and the performance is stable and reliable.
Application of laser ranging sensor
Car collision avoidance detector: In general, the laser ranging sensor of most existing car collision prevention systems uses laser beams in a non-contact manner to identify the distance between the target car in the front or rear situation, when the car When the distance is less than the predetermined safety distance, the car anti-collision system will perform emergency braking on the car, or send an alarm to the driver, or make an instant judgment and response to the car driving based on the speed of the target car, the distance between cars, the braking distance of the car, and the response time. Can greatly reduce traffic accidents. Its advantages are more obvious when used on the highway.
Traffic flow monitoring: The method of use is generally fixed on the gantry of a high-speed or important intersection. The laser emission and reception are vertically downward to the ground and aimed at the middle of a lane. When there is a vehicle passing, the laser ranging sensor can output the measured value in real time The relative change value of the obtained distance value is used to draw the outline of the measured vehicle. This measurement method generally needs to use a ranging range of less than 30 meters, and requires a relatively high laser ranging rate, and generally requires that it can reach 100 Hz. This can achieve very good results for monitoring important road sections, and can distinguish various types of vehicles. The sampling rate for vehicle height scanning can reach 10 cm per point (at 40Km/h, the sampling rate is 11 cm per point). It can distinguish the height limit, length limit and vehicle classification of traffic flow in real time, and can output the results quickly.
