The structure of the infrared rangefinder
As a precision measurement tool, infrared range finder has been widely used in various fields. Range finders can be divided into ultrasonic range finders, infrared range finders, and laser range finders. The so-called infrared rangefinder refers to the laser infrared rangefinder, that is, the laser rangefinder. Infrared rangefinder----an instrument that uses modulated infrared light for precise distance measurement, and the measurement range is generally 1-5 kilometers.
Infrared range finder is also called "infrared photoelectric range finder". A phase-type photoelectric rangefinder with infrared light as the light source. Gallium arsenide light-emitting diodes are usually used as the light source, and its light intensity changes with the injected electrical signal, so it has the dual functions of a light source and a modulator. Its measurement range is relatively short, mostly within 5 kilometers. Due to the semiconductorization of the light source of the infrared rangefinder, the gradual integration of electronic circuits, and the automation of the ranging process, the instrument has the advantages of small size, light weight, easy operation, fast ranging speed, and high precision. Widely used in water conservancy, mining, urban planning and military engineering survey.
The infrared rangefinder is mainly composed of a modulated light emitting unit, a receiving unit, a phase measuring unit, a counting and displaying unit, a logic control unit and a power converter. The light source is usually gallium arsenide (GaAs) semiconductor light-emitting diode. When a considerable current passes through the P-N junction of the GaAs diode, the P-N junction will emit near-infrared light with a wavelength of 0.72 μm and 0.94 μm, which is due to the electron-hole recombination in the doped GaAs semiconductor. , the excess energy is released in the form of photons. Moreover, the emitted light intensity will vary with the injection current. Therefore, if it is used as the light source of the rangefinder, the amplitude modulation of the emitted light intensity can be directly performed by changing the magnitude of the feed current, that is, this semiconductor light-emitting device has the dual functions of "radiation" and "modulation".
The infrared photodetection conversion device used to receive modulated light is usually a silicon photodiode or an avalanche photodiode, and these devices have a "photovoltage effect". When external light is irradiated on its P-N junction, due to the effect of photoelectric energy conversion, a potential difference can be generated at the two poles of P-N, and its magnitude will change with the intensity of incident light, thereby playing a role of "demodulation".
