From September 25th to 27th, the 'LAMOST Laser Beacon System' project at the National Astronomical Observatory in Hebei Province passed the acceptance of experts organized by the Chinese Academy of Sciences. The project was supported by the major science and technology infrastructure projects of the Chinese Academy of Sciences, and was supported by Nanjing Astronomical Optical Technology. The research team Li Guoping and the Fujian Institute of Physical Education Lin Wenxiong team worked together to complete.
The green laser developed by Lin Wenxiong as the core component of LAMOST, a laser beacon, produces a laser star of about 7 in the center of the telescope near 12 km, and samples the Rayleigh scattered light wavefront of the atmospheric molecules. Obtain the surface data of the telescope and transmit it to the actuator to realize the active optical correction of the telescope.
In the development process of the laser, in order to overcome the optical distortion problem of the ultra-long laser cavity, the innovative use of timing control and 4f image transfer technology broke through the bottleneck of the 20ns pulse width of general industrial use lasers, and developed a 65ns pulse width laser. The laser can be adapted to the ambient temperature of -30 ° C ~ +40 ° C, on the one hand, the material with lower thermal expansion coefficient is used as the laser bottom plate, and the laser cavity is in a stable cavity state through reasonable optical design; on the other hand, the self-developed self-developed Adapted to the optical mount, it can use its own deformation to offset the stress caused by the change of ambient temperature, and ensure the stability of the laser cavity when the ambient temperature changes. These technologies provide powerful for the realization of 7 laser stars and accurate measurement of Rayleigh scattered light wavefront. The protection, related research work applied for 3 patents, including 2 authorized patents, and published 1 article.
The laser indicators are better than the contract indicators: laser power 33W, power stability is 0.7%; repetition frequency 12kHz; pulse width 65ns; beam quality M2 = 1.3. At the acceptance summary meeting, the performance index of the laser is obtained by the expert group. It is highly praised that the artificial beacon generated by the laser greatly shortens the correction time of the active optics, improves the sky-lighting efficiency of LAMOST, and provides an important technical reserve for the laser guide system for the self-developed atmospheric correction in China.
