Fabry-Perot etalon-calibrating system and method for carrying out optical frequency compensation at cavity length scanning

Abstract

The invention provides a Fabry-Perot etalon-calibrating system and a Fabry-Perot etalon-calibrating method for carrying out optical frequency compensation at cavity length scanning. The system is established on the basis of a dual-edge direct-detecting wind-measuring laser-radar system with the operating wavelength of 355nm, the drift of laser frequency which is irradiated into the other Fabry-Perot etalon is monitored in real time by using the Fabry-Perot etalon with fixed cavity length when the transmittance of one Fabry-Perot etalon is scanned, the frequency abscissa of a transmittance curve which is obtained through scanning is corrected by utilizing the obtained laser-frequency drift through monitoring, so that the more accurate transmittance curve is obtained, calibration errors brought by the drift of incident laser frequency are eliminated, a more accurate frequency response function can be further obtained, and wind-speed errors are reduced. Through the Fabry-Perot etalon-calibrating system and the Fabry-Perot etalon-calibrating method, the problem of system errors brought by laser-frequency instability caused by the large-temperature-difference and strong-vibration environments of vehicle-mounted laser radars is effectively solved.

Description

technical field [0001] The invention belongs to the technical field of direct detection wind laser radar, and in particular relates to a Fabry-Perot etalon calibration system and method for long-term optical frequency compensation of a scanning cavity. Background technique [0002] The Doppler wind lidar technology based on Rayleigh scattering is the only laser remote sensing method for the middle and upper atmosphere. The basis of this wind measurement method is to obtain the accurate transmittance curve of the Fabry-Perot discriminator, so as to complete the calibration of the Fabry-Perot etalon. The existing scanning transmittance methods are as follows: [0003] The direct detection Doppler lidar of the University of Science and Technology of China uses the method of changing the etalon cavity length to scan the transmittance curve during the calibration process, so as to achieve the purpose of calibration. Depend on (where δ is the optical path difference, n is the ...

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Problems solved by technology

[0006] The existing three calibration methods for the etalon have the following disadvantages: the method of scanning the cavity length of the etalon, during the scanning process, due to the frequency drift of the laser incident into the etalon, this frequency drift will directly cause the scanned transmission Errors occur in the overrate curve; the method of scanning the refractive index needs to pressurize or decompress the cavity of the etalon during the scanning process, which is a slow process, so the scanning speed is very slow; the method of scanning the laser output frequency of the laser, due to It is also necessary to add another laser as a reference light to beat the outgoing laser to detect and stabilize the laser frequency. Therefore, complex optical path structures, optical devices and frequency stabilization methods are required to stabilize the laser frequency so that the laser frequency incident into the etalon The error caused by the jitter is controlled within an acceptable range

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