Rangefinder Concepts and Classification
Rangefinder is a kind of trajectory projection instrument, used to measure the target distance,shaker/oscillator, for trajectory projection. Rangefinder in many forms, usually a long cylinder, by the objective lens, eyepiece, distance measurement knob, used to determine the target distance.
Ultrasonic Rangefinder
Ultrasonic rangefinders make measurements based on the property of ultrasonic waves to reflect back when they encounter an obstacle. Ultrasonic transmitter to a certain direction to launch ultrasonic waves, in the launch at the same time to start timing, ultrasonic waves in the air propagation, on the way to encounter obstacles will immediately return to the ultrasonic receiver to receive the reflected wave will immediately interrupt to stop timing. Through the continuous detection of the wave generated by the launch of the wave encountered after the obstacle reflected by the return wave, so as to measure the launch of the ultrasonic wave and received the return wave of the time difference T, and then find the distance L.
Ultrasonic rangefinder, because ultrasonic waves are affected by the surrounding environment, so the general measurement distance is relatively short, the measurement accuracy is relatively low. The current use is not very broad, but the price is relatively low, generally a few hundred dollars or so.
Infrared distance meter
With modulated infrared light for precision ranging instruments, measuring range is generally 1-5 kilometers. The use of infrared propagation of the principle of non-diffusion: because infrared light in the refractive index across other substances is very small, so long-distance rangefinders will consider infrared light, and infrared propagation is time-consuming, when infrared light from the rangefinder to meet the reflector was reflected back to be accepted by the rangefinder and then according to the infrared light from the time of issue to be accepted by the infrared propagation speed can be calculated to distance
The advantages of infrared ranging is cheap, easy to make, safe, the disadvantage is the low accuracy, the distance is close, the direction is poor.
