Multi-wavelength Cascade Excitation Sodium Laser Guide Star and Adaptive Optics Correction Method

Abstract

The invention belongs to the field of self-adaptive optics, and provides a multi-wavelength cascade excitation sodium laser guide star and a self-adaptive optical correction method. The multi-wavelength cascade excitation sodium laser guide star comprises a laser source, a laser emitter, a fluorescence reception apparatus, a wavefront detection apparatus, a wavefront correction system and an imaging apparatus. Laser wavelengths provided by the laser source at least include one or more than one wavelength of the following types: a wavelength of 589nm, a wavelength of 819nm, a wavelength of 1847nm, a wavelength of 616nm and a wavelength of 1140nm. Under the effect of the lasers, sodium atoms in an atmosphere sodium layer is subjected to cascade excitation to reach a high level, and release beacon lights of different wavelengths in a process of transition to a low level in a level by level or a level skipping mode. Through the reception and measurement of the wavefront signals of the beacon lights, an object image can be corrected according to the wavefront signals of the beacon lights. The invention can provide the plurality of wavelength beacon lights, so that correction of wavefront distortions of other wavelengths is convenient.

Description

technical field [0001] The invention belongs to the field of adaptive optics, and in particular relates to a technology for providing multi-wavelength beacon light for an adaptive optics system by using a sodium atomic layer in the middle layer of the atmosphere. Background technique [0002] When the beam is transmitted in the atmosphere, due to the influence of atmospheric turbulence, the wavefront of the beam will be distorted, and the impact on the ground-based astronomical observation is manifested as a decrease in image resolution and blurring of the observation target. At present, in order to improve the resolution of observation targets, adaptive optics based on artificial guide star technology has attracted more and more attention from researchers. The working principle of the sodium laser guide star adaptive optics system is: use the laser to excite the sodium atoms in the sodium layer at a distance of 80-120 kilometers from the ground to an excited state, and then...

AI Technical Summary

Problems solved by technology

And fundamentally speaking, the single-wavelength beacon light cannot correct the oblique aberration caused by the atmosphere. In practical applications, it is often necessary to find a natural guide star besides the artificial guide star to assist in correcting the oblique aberration.

In addition, the number of sodium atoms available in the thin sodium atomic layer is limited, and the current sodium laser guide stars only use the two energy levels of the ground state and the first excited state of sodium atoms, so they are limited by the saturation effect of the two-level system Limitation, simply increasing the 589nm laser intensity cannot obtain a linear increase in the brightness of the sodium guide star

In addition, the peak response band of photodetectors commonly used at present is in the near infrared, and 589nm is not in the peak response band of the detector, which is not conducive to detection

[0004] It can be seen from the above that the existing sodium laser guide star beacon light has a single wavelength and is far away from the working band of the telescope; the oblique aberration caused by the atmosphere cannot be corrected; the brightness is limited by the saturation effect of the two-level system; the beacon light is not in the Disadvantages such as detector peak response band

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