Design, Manufacture and Evaluation of Optical Lens for Infrared Use

Abstract

Developments of infrared lenses used at 3-14 μm are described. Germanium crystal is used as optical materials. Because the material's index is high and long wavelengths are used, it is possible to design nearly ideal lens. These lenses have small chromatic aberration, and therefore, can be used in infrared optical systems covering the wide band of wavelength with the combination of anti-reflection coatings and interference filters. Finally, the performances of manufactured lenses estimated with the modulation transfer function (MTF).