1. Laser range finder Laser range finder is an instrument that uses laser to accurately measure the distance of the target.
When the laser range finder is working, it emits a very thick laser beam to the target, and the photoelectric element receives the laser beam reflected by the target. The timer measures the time from emission to reception of the laser beam and calculates the distance from the observer to the target.
The laser range finder is the most commonly used range finder at present. Laser range finders can be divided into handheld laser range finders (measurement distance 0-300 meters) and telescope laser range finders (measurement distance 500-20000 meters).
2. Ultrasonic range finder Ultrasonic range finder is based on the characteristics of ultrasonic reflection when encountering obstacles.
The ultrasonic transmitter emits ultrasonic waves in a certain direction and starts timing at the same time.
When ultrasonic waves travel through the air, when they encounter obstacles on the way, they will return immediately. When the ultrasonic receiver receives the reflected wave, it immediately interrupts and stops timing.
By continuously detecting the echoes reflected by obstacles after the generated waves are emitted, the time difference t between the emitted ultrasonic waves and the received echoes is measured, and then the distance L is calculated. Ultrasonic range finder, because the ultrasonic wave is less affected by the surrounding environment, usually the measurement distance is relatively long, and the measurement accuracy is relatively high. At present, the scope of use is not very large, but the price is relatively high, usually around several hundred yuan.
3. Infrared
rangefinder is an instrument that uses modulated white light to measure distance accurately, and the measurement range is usually 1-5 kilometers.
It uses the principle of non-diffusion of infrared propagation: because infrared rays have a large refractive index when passing through other substances, infrared rays are considered in remote measuring instruments, and when infrared rays are emitted from the rangefinder and meet the reflector, it takes time for the infrared rays to propagate, It is received by the range finder, and then the distance can be calculated based on the time from sending out to receiving the infrared rays and the propagation speed of the infrared rays.
The advantages of infrared ranging are cheap, easy to control, and safe, but the disadvantages are high accuracy, long distance, and low directionality. The technology of infrared range finder and ultrasonic range finder is relatively advanced. Generally speaking, the infrared range finder refers to the laser range finder.
