Design of Mirror and Whiffle Tree Mechanism for Ground and Space Application

Abstract

CARTOSAT -3 spacecraft would be a high resolution earth imaging satellite. The satellite will acquire high resolution optical imaginary with its on board telescope camera optics that will collect images simultaneously of 0.25 meter resolution in panchromatic band (400-950 nm), less than 1 meter resolution in multi spectral bands. The pay load optics development requires large size optical mirrors and selection of the best suitable material for mirror. A optimum design of mirror is proposed for high resolution satellite for GPS system in launch vehicle. The finite element method is used to build the parameterizations model for the optimum structural design. The structural parameters such as thickness of the mirror and faceplate have more effect on the mass of the mirror. Maximum deformation of the mirror surface are selected as the design variables and weight reduction has considered as the design function.

During fabrication and testing of high quality surface finish mirror, it is required to hold the mirror at numbers of points to mitigate the effect of gravity on the optical surface of the mirror. To hold the mirror at numbers of support points, a mechanism, called whiffle tree mechanism, is designed and prototype testing has been carried out on analogues system. For light weight mirror, selection of 18 points discrete whiffle tree mechanism gives satisfactory result.