Three-shell-based lens barrel for the effective athermalization of an IR optical system

Abstract

We have developed a new IR optical system that consists of three mirrors and four lenses, and that operates in the temperature range 8°C-32°C. This temperature range can induce thermoelastic deformation in the lenses and their mounting subassembly, leading to a large defocus error associated with the displacement of the lenses inside the barrel. We suggest using a new three-shell-based athermalization structure composed of two materials with different coefficients of thermal expansion (Invar and aluminum). A finite element analysis and the experiment data were used to confirm that this new athermalization barrel had a defocus error sensitivity of 11.6 nm/°C; this is an improvement on the widely used conventional single-shell titanium barrel model, which has a defocus error sensitivity of 29.8 nm/°C. This paper provides the technical details of the new athermalization design, and its computational and experimental performance results.

110 °C range athermalization of wavefront coding infrared imaging systems

“…Available approaches of infrared athermalization focus on the active mechanical [3], passive mechanical [4] and passive optical [5] measures. As one of typical computational imaging techniques, wavefront coding technique is a powerful hybrid optical-digital technique for increasing a focal depth of imaging and for widening an athermalization temperature range.…”

A wide-FoV athermalized infrared imaging system with a two-element lens

“…Available approaches of infrared athermalization include the active mechanical [2], passive mechanical [3] and passive optical [4] measures. As a computational imaging technique, wavefront coding is a powerful hybrid optical-digital technique for extending an operating temperature range of an infrared imaging system [5][6][7][8].…”

ZnSe-material phase mask applied to athermalization of infrared imaging systems

“…In order to maintain the in-focus imaging quality over a wide range of environmental temperatures, many approaches have been developed to achieve the athermalization of infrared imaging systems such as the mechanically active method [3], the mechanically passive method [4], and the optically passive method [5]. Compared with those previous methods, the athermalization by wavefront coding technique has many advantages, such as avoiding the use of less desirable and exotic materials relaxing manufacturing tolerances for some optical and mechanical elements and shortening time for adjusting focus [6,7].…”