Structure and Categorization of Infrared Distance Meters
The infrared rangefinder mainly consists of a modulated light emitting unit, a receiving unit, a phase measuring unit, a counting display unit, a logic control unit, and a power converter. Its light source is usually a gallium arsenide (GaAs) semiconductor light-emitting diode. When a considerable current flows forward through the P-N junction of a GaAs diode, near-infrared light with wavelengths of 0.72 μ m and 0.94 μ m is emitted from the P-N junction. This is due to the excess energy released in the form of photons during electron hole recombination in doped GaAs semiconductors. And the emitted light intensity will vary with the change of injected current. Therefore, by using it as the light source for a rangefinder, the emitted light intensity can be directly modulated by changing the magnitude of the feeding current, which means that this semiconductor light-emitting device has dual functions of "radiation" and "modulation".
The infrared photoelectric detection conversion devices used to receive modulated light are usually silicon photodiodes or avalanche photodiodes, which have a "photovoltaic effect". When external light shines on its P-N junction, a potential difference can be generated at the P-N poles due to the effect of photoelectric energy conversion, and its magnitude will vary with the strength of the incident light, thus playing a role of "de modulation".
Classification of infrared rangefinders
Infrared rangefinders can be divided into two categories, mainly including handheld laser infrared rangefinders and telescope style laser infrared rangefinders.
The measurement distance is generally within 200 meters, with an accuracy of about 2mm. This is currently the most widely used laser infrared rangefinder. In terms of functionality, in addition to measuring distance, it can generally also calculate the volume of the measured object.
Telescope style laser infrared rangefinder
The measurement distance is generally around 600-3000 meters. This type of infrared rangefinder measures a relatively long distance, but the accuracy is relatively low, usually around 1 meter. The main application scope is long-distance field measurement.
The telescope laser infrared rangefinder is a long-distance laser infrared rangefinder that is currently widely used outdoors. The telescope laser infrared rangefinder measures accurately and has a fast response speed.
