What is an infrared rangefinder?
Infrared rangefinder is also called infrared photoelectric rangefinder. Phase photoelectric rangefinder using infrared light as the light source. The light source usually uses gallium arsenide light-emitting diodes, whose light intensity changes with the injected electrical signal, so it has the dual functions of a light source and a modulator. The measurement range is short, mostly within 5 kilometers. As the light source of the infrared rangefinder is semiconductorized, the electronic circuit is gradually integrated, and the ranging process is automated. It has the advantages of small size, light weight, simple operation, fast ranging speed, and high accuracy. It is widely used in water conservancy, mining, urban planning and military engineering surveying.
The infrared rangefinder considers the principle of infrared non-diffusion when transmitting. Since infrared rays have a small refractive index when passing through other materials, long-distance rangefinders will consider infrared rays, and it takes time for infrared rays to propagate. When the red line is emitted from the rangefinder and the reflector is reflected back to the rangefinder to receive, the distance can be calculated based on the time from when the infrared is emitted to the reception and the propagation speed of the infrared. Therefore, the industry calls it a laser red light photoelectric rangefinder, and its magnet is a special strong magnetic permanent magnet.
The frequency f of the modulation signal generated by the main control oscillator (that is, the main oscillator) is amplified and then added to the Gaas light-emitting tube, and the infrared modulated light is modulated by the current, and it is emitted from the emission optical system to the mirror of the mirror station. After reflection, the returned light is received by the optical system and reaches the silicon photodiode to obtain a high-frequency ranging signal through photoelectric conversion.
In the automatic infrared rangefinder, a logic command circuit is set for program control. The new rangefinder developed in recent years adopts a microprocessor system, which can not only complete the above-mentioned program control, but also develop other automatic test functions, including range finding, attribution and self-checking, which is very convenient to use.
The infrared rangefinder is mainly composed of a dimming transmitting unit, a receiving unit, a phase measuring unit, a counting display unit, a logic control unit and a power converter. The light source is usually an arsenide semiconductor light-emitting diode. When a considerable current passes through the PN junction of a Gaas diode in the forward direction, near-infrared light with wavelengths of 0.72μm and 0.94μm will be emitted from the PN junction. In the form of release. Moreover, the light intensity will vary with the injection current. Therefore, as the light source of the rangefinder, the light intensity can be directly adjusted by changing the size of the feeding current, that is, this semiconductor light-emitting device has the dual functions of radiation and adjustment.
The infrared photoelectric detection conversion device used to receive modulated light is usually a silicon photodiode or an avalanche photodiode, which has a photovoltage effect. When external light irradiates its P-N junction, due to the effect of photoelectric energy conversion, a potential difference can be generated between the P-N poles, and its size will change with the intensity of the emitted light, thereby playing the role of demodulation.