Progress in LAMOST optical system

摘要

This paper presents the recent progress in the optical system of LAMOST project: (1) The image quality at the edge of the field of view and the worst sky area is about 1.76 arc seconds. To improve this value, many aspherical lenses with 3 mm in diameter will be attached to some of 4000 optical fibers. With maximum 6.6 microns asphericity, these lenses could compensate the residual off-axis aberration of the optical system and obtain much better image quality, thus in any case the image quality could less than 0.6 arc seconds in diameter. (2) At the open air, an outdoor experiment program for creating the aspherical surface and accurately measuring the wave front shape of the active Schmidt correcting plate, which is with the full scale of the sub-system of the telescope, is introduced here. (3) Some further consideration and modification for the active support of each sub-mirror of the Schmidt correcting plate is discussed also in this paper. The presentation in this paper showed that the LAMOST is very likely to get much better quality even it is with a very large field of view, and its key technology ― active optics is also reaching the realization.