Infrared rangefinder
An instrument that uses modulated infrared light for precise ranging, and the measuring range is generally 1-5 kilometers. The principle of non-diffusion of infrared rays is used: the reason is that the refractive index of infrared rays is very small when passing through other substances, so long-distance rangefinders will consider infrared rays, and the propagation of infrared rays takes time. The emitted light is reflected back by the reflective object and received by the rangefinder, and then the distance can be calculated according to the time from when the infrared ray is emitted to when it is received and the propagation speed of the infrared ray.
The advantages of infrared ranging are cheap, easy to manufacture, and safe, but the disadvantages are low accuracy, short distances, and poor directivity.
Ultrasonic rangefinder
The ultrasonic range finder is measured according to the characteristics of ultrasonic waves reflected from obstacles. The ultrasonic transmitter emits ultrasonic waves in a certain direction, and starts timing at the same time. The ultrasonic wave propagates in the air, and it returns immediately when it encounters an obstacle on the way. The ultrasonic receiver immediately stops the timing when it receives the reflected wave. By continuously detecting the echoes reflected by obstacles after the generated waves are emitted, the time difference T 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 greatly affected by the surrounding environment, so the general measurement distance is relatively short, and the measurement accuracy is relatively low. At present, the scope of use is not very broad, but the price is relatively low, generally about a few hundred yuan.
Laser rangefinder
A laser rangefinder is an instrument that uses a laser to accurately measure the distance to a target. The 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. distance.
Laser rangefinders are currently the most widely used rangefinders. Laser rangefinders can be classified into handheld laser rangefinders (measurement distance of 0-300 meters), telescope laser rangefinders (measurement distance of 500-3000 meters) .
