Spaceborn optical payload consists of optical elements supported by mechanical structure in desired orientation. Mechanical structure made up of various dissimilar materials like aluminum & invar possess dissimilar thermo-elastic behavior. Opto-mechanical assembly subjected to temperature change will results to change in optical element orientation which ultimately leads to change in optical parameters like registration. This is mainly due to dissimilar materials subjected to temperature variation will result to structural distortion. Use of dissimilar materials in an Opto- mechanical payload affects the angular stability of optical element due to temperature variation and results to change in optical element orientation. Flexure is required to be introduced within the opto-mechanical system having dissimilar materials to accommodate differential thermal expansion due to temperature variation and to maintain the registration. This paper explains, stability in dichroic element orientation of an opto-mechanical payload having dissimilar material & flexure design to maintain the orientation in opto-mechanical payload subjected to temperature variation without deterioration of fundamental frequency. It also explains theoretical thermo-elastic analysis and experimental test for validation of design, static and dynamic structural analysis like frequency response analysis to check the flexure survivability for vibration load.