The stringent and conflicting requirements of optomechanical instruments and the ever-increasing need for higher resolution and quality imagery demands a tightly integrated design approach. The aim of this study is to drive the thermomechanical design of multiple components of an optomechanical instruments by the system’s optical performance. This work addresses the combination of structural-thermal-optical performance analysis and multicomponent topology optimization while taking into account both component and system level constraints. A 2D two-mirror example demonstrates that the proposed approach is able to improve the system’s spot size error by 95% compared to uncoupled system optimization to below the system's diffraction limit.