Analysis of thermo-opto-mechanical system and stress birefringence in elastically bonded optics for space applications

Abstract

Optomechanical systems are often required to function over a broad temperature range, which can significantly influence their performance. In this paper, we explore how temperature fluctuations affect typical optomechanical systems and investigate the thermal stresses induced by continuous edge, six-point contact, and face elastomeric bonds using analytical methods and finite element analysis (FEA). Additionally, the finite element method obtains thermoelastic stress analysis. In Ansys software, an optomechanical system with thermal loads accurately calculate the thermal strain and radial stress. We derived analytical equations for thermalized edge bond thickness and thermoelastic stress analysis, including thermal stress, thermal strain, radial stress, and thermal optical path difference (OPD). Thermal stress birefringence (OPD) varies with temperature and can lead to thermo-optic distortion, presenting serious challenges for high-resolution optical systems, particularly in diffraction-limited systems, where maintaining Rayleigh criteria is crucial. The primary objective of this research is to validate and evaluate an optimized configuration of the optomechanical assembly for the Alsat-1B satellite payload, aiming to minimize thermal stress and stress-induced birefringence. Our analysis confirms that the proposed analytical solutions exhibit low estimation errors for thermal stresses when compared to finite element analysis. Moreover, when the optical path difference (OPD) is maintained well below the standard quarter-wave diffraction tolerance, these solutions become valuable tools for decision-makers and optical engineers in the development of spaceborne optomechanical systems.