What are the thermal characteristics of large-aperture infrared lenses at different temperatures?

As the temperature drops, the thermal deformation of the optical lens increases. This is because the lens barrel,O-ring and other mechanical parts squeeze the lens, which increases the thermal stress of the lens. The surface shape of the lens changes uniformly in a low temperature environment. This is because the lens is radially squeezed by the mechanical structure. When the temperature rises to 60°C, the surface shape of the lens changes irregularly, Larger thermal deformation also occurs in a relatively normal temperature environment, but less thermal deformation than in low temperature environment, this is because there will be a gap between mechanical components and lens in high temperature environment, which reduces the thermal stress of the lens, and the thermal deformation of the lens is correspondingly reduced; compared with high temperature and low temperature environment The image quality will decrease in normal temperature environment, and the imaging performance in low temperature environment is worse than that in high temperature environment.

Generally, the first lens of a large-aperture infrared lens has a larger aperture than a conventional infrared lens, and the luminous flux entering the infrared system is more, causing external stray light to easily enter the opto-mechanical system. When there is a strong radiation source outside the field of view, the observed target signal energy is very weak, causing the non-target imaging energy outside the field of view to exceed the target imaging energy, so that the low-contrast target image or image details are overwhelmed, causing stray light on the image surface of the detector system.