Laser radar on basis of optical fiber mode field adapter

Abstract

The invention discloses laser radar on the basis of an optical fiber mode field adapter. The laser radar has the advantages that the optical fiber mode field adapter is used in a telescope of the laser radar, an input end of the optical fiber mode field adapter is a large-mode-field optical fiber end, the large-mode-field optical fiber end is connected with an output end of an optical receiving and transmitting module and is used for receiving atmospheric echo signals, an output end of the optical fiber mode field adapter is a small-mode-field optical fiber end, the small-mode-field optical fiber end is connected with an optical receiver and is favorable for optical filtering and optical signal extraction, and accordingly the cost of the laser radar can be reduced; the problem of contradiction between received signal view field angles and optical data processing of existing laser radar can be ingeniously solved by the aid of the optical fiber mode field adapter, view field angles can be expanded while the echo signal coupling efficiency is guaranteed, the performance of the laser radar can be improved, the requirements of the optical receiver and photoelectric detectors on small mode fields can be met, follow-up data processing difficulty can be lowered, the integral performance of the laser radar can be improved, and the application range of the laser radar can be expanded.

Description

technical field [0001] The invention relates to a laser radar, in particular to a laser radar based on an optical fiber mode field adapter. Background technique [0002] The basic principle of meteorological lidar is: the outgoing laser pulse interacts with the atmosphere, the atmospheric backscattering signal is collected by an optical antenna and then input to an optical receiver, and a series of key atmospheric parameters are obtained after photoelectric detection and data processing. Such as aerosol concentration, PM2.5 value, cloud height, temperature, humidity, visibility, atmospheric composition (such as water vapor, various polluting gases), etc. [0003] Lidar requires that the viewing angle of the receiving telescope is greater than the divergence angle of the emitting laser. The inventors of the present invention have found that in order to meet the above requirements when designing the laser radar, it is necessary to reduce the divergence angle of the emitted la...

AI Technical Summary

Problems solved by technology

[0004] The inventors of the present invention found that increasing the focal length of the transmitting telescope will lead to an increase in the volume of the telescope module, and due to the increased focal length, the laser beam is more easily affected by vibration and changes in environmental temperature, humidity and pressure, thereby reducing the stability of the system

At the receiving telescope end, when the numerical aperture NA of the coupling fiber is constant, reducing the focal length of the telescope will reduce the effective receiving area of ​​the receiving telescope, thereby reducing the detection performance of the lidar; if a large mode field fiber coupling is used, Then the subsequent optical signal processing needs to use large mode field fiber, which greatly increases the difficulty of optical signal detection and processing. Some optical receivers cannot work with large mode field fiber. In addition, multimode photodetectors also have high cost and high performance. bad question

Therefore, large mode field fibers limit the application of some lidars, especially wind lidar, depolarization lidar and temperature lidar

These defects greatly limit the development of lidar

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