Designing dual-band athermal refractive-lens IR objectives

Abstract

The possibility of achieving superior optical characteristics and passive athermalization in dual-band IR objectives of a simple design is shown. This is ensured, in particular, by using refractive lenses made of chalcogenide glasses in the optical scheme. Recommendations regarding the layout of the optical scheme and obtaining initial design parameters for the subsequent optimization are given. The reliability and effectiveness of the recommendations are confirmed by the results of designing a super-aperture refractive-lens objective operating in the mid- and long-IR subranges and forming a high-quality polychromatic image on the matrix of an uncooled microbolometer in the operating temperature range from – 40°C to + 60°C.

Design and Research of a Dual-Band Ir Lens

“…For an infrared objective in a wide range, there is a strong dependence of the refractive index of the optical materials used on the wavelength. A major problem in the design of a dual band IR lens is the need for the simultaneous correction of chromatic aberration in two relatively wide and distant from each other spectral ranges [9], [10]. The most common way to solve this problem is to use combinations of different optical materials and subsequent analysis and optimize the system using optical software.…”

“…In it, one lens is made of chalcogenide glass and the other -of ZnSe or ZnS. Here the chromatic correction is good, but according to [9] the use of chalcogenide glasses is preferably to be in the LWIR range of the spectrum.…”