Semiconductor laser ceilometer with double-optical-axis structure

Abstract

The invention discloses a semiconductor laser ceilometer with a double-optical-axis structure and belongs to the technical field of semiconductor laser ceilometers. The signal-to-noise ratio of the system is improved by performing high-speed signal acquisition on a signal subjected to direct-current amplification isolation by using an ADC chip and performing multiple data cumulative averaging andother processing by using an FPGA. The double-optical-axis design is adopted, and advantages are as follows: the structure is simple, saturation of a receiver can be avoided and optical interference can be effectively avoided without compensation measures. Meanwhile, the detection capability of the near-field cloud height can be improved; the long-focus large-aperture lens is simple in structure,low in cost and easy to realize; the influence of stray light generated by scattering of the inner wall of the system on a near field is reduced by adopting a spatial diaphragm; an optical filter is an interference optical filter with the parameters as follows: central wavelength is 905 nm, the diameter is 25.4 mm and the bandwidth is 25 nm; the transmittance in a band pass is about 50%-75%, the transmittance in a band stop is less than 1%, background light of other various wavelengths is effectively inhibited, echo light of a working band only enters a detector, and the signal-to-noise ratioof the system is improved.

Description

technical field [0001] The invention relates to a semiconductor laser ceilometer, in particular to a semiconductor laser ceilometer with a dual optical axis structure, and belongs to the technical field of semiconductor laser ceilometers. Background technique [0002] Water vapor, water droplets, ice crystals, etc. and mixtures of these substances floating in the air have become our common clouds. More than 50% of the world's sky is covered with clouds of various shapes and sizes. These clouds are distributed on the ground and within 20 kilometers of the sky, and their bottoms do not touch the ground. [0003] The water vapor cycle on the earth forms clouds. The sun radiates on the surface of the water, and the water vapor evaporates into water vapor. When the water vapor in the atmosphere is supersaturated or cold, it will liquefy into small water droplets or condense into ice crystals, which are suspended in the air. Clouds formed in the sky. Clouds come in all shapes an...

AI Technical Summary

Problems solved by technology

[0007] The semiconductor laser ceilometer in the prior art has limited detection height and high noise level when measuring the cloud, needs compensation measures to avoid receiver saturation and effectively avoid optical interference, weak detection ability of near-field cloud height, noise Strong astigmatism, insufficient detection accuracy, weak ability to filter out external stray light, semiconductor laser cloud height detection, from environmental atmospheric instability factors such as solar radiation, atmospheric transparency, atmospheric turbulence, and various internal components of photodetectors Electrical noise and background radiation noise, these noises will enter the signal detection system, they will not only increase the design difficulty of the signal detection system, but also reduce the detection performance of the entire system

These factors greatly reduce the signal-to-noise ratio of the laser signal received by the semiconductor laser ceilometer photodetector, and the signal with a lower signal-to-noise ratio cannot be directly used to invert cloud height information. For this reason, a semiconductor laser with a dual optical axis structure is invented. Laser ceilometer to optimize the above problems

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