Concept for a passive athermalization of additively manufactured and monolithic mounting structures

Abstract

Passive athermalization techniques for optical systems combine materials in the mounting structure with different coefficients of thermal expansion (CTE) to minimize thermally driven shifts. However, such an approach requires complex structures to be manufactured with multiple high-precision opto-mechanical components. Our concept utilises a monolithic and additively manufactured mounting structure and a housing made of a second material to generate mechanical stresses caused by temperature fluctuations. The difference in coefficients of thermal expansion induces these mechanical stresses during temperature changes, resulting in elastic deformations of the inner monolithic structure. The magnitude of the local deformation of the monolithic structure is adjusted via the stiffness between the optical elements. This allows to control the displacement for each optical element such that their positions remain unaffected by a thermal load and thus passively athermalizes the optical system.