Search

Lateral support has a significant effect on the deformation of thin primary mirror. This paper deals with the analysis and optimization procedure on the “push-pull-shear” lateral support of thin meniscus mirror. Three steps were carried out in the lateral support optimization. Firstly a finite element model (FEM) was build for further analysis, then according to its structural characteristic, the ratio between the tangential force and the radial force was analyzed during the first optimization; In order to make the lateral forces with the same value, equal angle distance was changed to different angle distances during the second optimization, also lateral support position and magnitude of the lateral forces were given; during the last analysis, a portion of axial force was exerted at the inner ring, the response curve between the inner ring axial force and the RMS in Z direction of the mirror was plotted. The final result showed that the RMS value was decreased from 12.168nm to 3.253nm in Z direction. The optimization procedure provided a feasible way for lateral support of thin meniscus mirror.

In order to ascertain the effects of main errors of alt-alt photoelectric telescope on measurement accuracy, orientation error is analyzed. For analyzing optical, mechanical and electrical errors from measured target to telescope picture, we construct 7 coordinates such as: the earth's core coordinate, alt-alt coordinate, etc., carry through 21 times coordinate transformation, form measuring equation with 26 variables. And we utilize Monte Carlo method to calculate the orientation error, analyze the effects of errors upon pointing. The result indicates that the measuring error standard deviation of alt-alt telescope is minimum value about 10" at the zenith zone. And the deviation increases with the rotation angles of longitude and latitude axes. The model and the method not only can analyze and synthesize the main errors, but also provide a reference to the whole design.

Corrective force solving is a critical technology of the active optics. A method to solve active optics corrective force is introduced, which is based on Householder transform of Zernike polynomial wave front fitting, this method is different from the traditional least square method and Gram-Schmid orthogonal method, because it does not bring ill-conditioned polynomial without constructing normal equation, so it can avoid calculation error, wave front fitting is precision. Based on the coefficient of the Zernike polynomial and the response function of the each actuator, the stiffness matrix of the primary mirror is built, and then adopting the damp least square method to calculate corrective force. Based on this method, φ400m test mirror is simulated many times, the calculation result approve: if the Householder transform is adopted, wave front fitting is precision, the result is stabilization and corrective effectiveness is better.