Adaptive Optics(AO) technology will be limited by the beacon or guide star problem when the object that is observated couldn’t provide real-time wavefront information, or there is no bright enough beacon within the isoplanatic field. Therefore, it is important to use artificial guide star, that is LGS(Laser Guide Star). In this dissertation, laser guide star background and development are introduced first, Second , after an introduction of the basic concepts about turbulence and laser guide star, based on laser beam propagation in the turbulence theory , the laser beacon expander problem has been analyzed by the author. Based on the filter function of the atmospheric turbulence sensing geometry, the variances of the residual wave front distortion resulting from focal anisoplanatism were derived. The analysis of results shown that focal anisoplanatism error for Rayleigh laser guide star was very severity. This error would eliminated by use of multiple laser guide stars. In this paper, author investigated the residual wave front error according to use of laser guide stars. At the same time, when using adaptive optics system astronomical optical interferometer to observe faint astronomical object, the differential piston angular anisoplanatism was derived by the author first time. Most of researcher have proposed the concept to detect the tip-tilt information from laser guide star, such as polychromatic LGS , auxiliary telescope, auxiliary laser ,et al.. In the following of this paper, author will combine 1.2 m telescope adaptive optics system to put forward a scheme how to retrieve the absolute tip-tilt. The project diameter, the distance between laser projector and telescope, all of parameters were investigated in detail. According to returned signal level and guide star spot size for laser guide star, laser pulse eneney, sampling depth were investigated in detail. Based on the technology of LGS launched and received in co-aperture, author has designed a new form of a fast mechanical shutter for protect wavefront sensor damage by scattered light.
修改评论