A New Solving Method of the Athermal Bonding Thickness in Lens Mount

Abstract

Adhesives are widely used in the design of optical and mechanical structures. For optics fixed by adhesive bonding, the mismatch of the thermal expansion coefficient of the materials among the lens, the adhesive layer and the frame will bring thermal stress in the radial direction of the lens, which will affect the imaging of entire optical system. Studies have shown that by changing the thickness of the adhesive layer can reduce or even eliminate the radial stress caused by temperature changes, so it is critical to obtain the thickness with low(zero) radial stress. Based on the derivation of the existing athermal bond thickness equation, this paper proposes a new bonding layer constraint condition assumption, introduces the thermal expansion coefficient scale factors k1, k2, and derives a novel athermal bond thickness equation. Then, using the finite element method, the thermal stress simulation analysis of two adhesive lens assemblies with different count materials is solved, by comparing the simulated value with the analytical solutions, it’s found that the errors of both are within 10%, which shows that the newly derived equation has sufficient accuracy to meet the needs of engineering application.