1. Laser rangefinder.
A laser rangefinder is an instrument that uses lasers for precise distance measurement. The laser rangefinder shoots a very thin laser beam toward the target during operation, and the photoelectric element receives the laser beam reflected by the target.
Airborne laser rangefinders are the most widely used
Entfernungsmesser. It can be divided into handheld laser rangefinder (measurement distance 0-300 meters), telescope laser altimeter (measurement range 500-3000 meters).
2. Ultrasonic rangefinder.
The ultrasonic rangefinder is based on the characteristics of ultrasonic backtesting when encountering obstacles. The ultrasonic transmitter emits ultrasonic waves in a certain direction and starts timing at the same time. The ultrasonic waves propagate in the air and return immediately when encountering obstacles. The ultrasonic receiver stops timing when it receives the reflected waves. By continuously detecting the echoes reflected by the obstacles encountered after the ultrasonic emission, the time difference between the transmitted ultrasonic waves and the received echoes is measured, and then the distance L is calculated.
Ultrasonic range finder, because the ultrasonic wave is affected by the surrounding environment, so the general measurement distance is relatively short, and the measurement accuracy is relatively low.
3. Infrared rangefinder.
Using a modulated infrared light precision
Entfernungsmesser, the measurement range is generally 1-5 kilometers. Using the principle of non-diffusion of infrared transmission: Since the refractive index of infrared rays is small when passing through other materials, the long-distance rangefinder will consider infrared rays, and the propagation of infrared rays takes time. The reflective surface reflects back and is received by the rangefinder, which then calculates the distance based on the time from when it is emitted to when it is received and the speed at which the infrared rays travel.
The advantages of infrared ranging are cheap, easy to make, safe and reliable, but the disadvantages are low accuracy, short distance and poor directionality.
