At present, the market is full of a variety of rangefinders, including industrial-grade, suitable for underwater work, suitable for foggy weather, indoor use, remote, high frequency. According to the working principle, we can divide the range finder into the following three categories:
Laser Range Finder: Laser Range Finder is one of the most widely used sensors. Its design is flexible, compact and easy to operate. It is very popular in industry and household. It is an instrument that uses laser to measure the distance of the target accurately. When working, a very fine laser beam is emitted to the target, and the reflected laser beam is received by the optoelectronic element. The time from the launch to the reception of the laser beam is measured by a timer, and the distance from the observer to the target is calculated.
Ultrasound Range Finder: Ultrasound ranging, because the impact of the surrounding environment is greater, so the general measurement distance is relatively short, measurement accuracy is relatively low. At present, the scope of use is not very broad, but the price is relatively low, generally about several hundred yuan. According to the characteristics of the reflection of the ultrasonic wave when it encounters obstacles, it is measured. Ultrasound transmitter transmits ultrasound in a certain direction. At the same time, it starts timing. Ultrasound spreads in the air. When it encounters obstacles on the way, it returns immediately. When the ultrasonic receiver receives the reflected wave, it immediately interrupts the timing. By continuously detecting the echoes reflected by obstacles after the generated waves are emitted, the time difference T between transmitting and receiving the echoes is measured, and then the distance L is calculated.
Infrared Ranging Instrument: The advantages of infrared ranging are cheap, easy to manufacture, safe, but the disadvantages are low accuracy, close distance and poor directivity. Modulated infrared light for precision ranging instruments, ranging is generally 1-5 km. The non-proliferation principle of infrared transmission is used: because the refractive index of infrared ray is very small when it travels through other substances, the long-distance rangefinder will consider infrared ray, and the transmission of infrared ray takes time. When infrared ray is emitted from the rangefinder and the reflector is reflected back, the rangefinder receives it and then receives it according to infrared ray. The distance can be calculated by the time the line is sent to be received and the transmission speed of infrared ray.