Design and analysis of the hemispherical optical window used in the deepest sea

Abstract

Aiming at the hemispherical optical windows made of brittle materials such as optical glass, transparent ceramics and sapphire, there are potential cracks at bottom plane edge which affect the safety and reliability of optical equipment used in the deepest sea. The compression design of the hemispherical optical window based on transition gaskets is studied. First, the finite element simulation shows that the stress concentration of the hemispherical optical window is located at the edge of the bottom plane. Then, simulations of gaskets with the same thickness and different materials are carried out, and the influence law of gaskets with different materials on the stress of the hemispherical optical window is obtained; The gaskets with the same material and different thickness are also compared and analyzed, and the effect of the gasket thickness on the stress of the hemispherical optical window is obtained. The pressure test was conducted for the transparent ceramic hemispherical optical window. The results show that the inner and outer edges of the bottom plane of the hemispherical optical window with the silicon nitride gasket at the bottom are not damaged, but obvious indentations on the inner edge of the optical window without the gasket. Adding a gasket made of the material with large Young's modulus at the bottom can effectively reduce the extreme stress of the hemispherical optical window, and the greater the gasket thickness of the same material, the smaller the extreme stress of the hemispherical optical window.