Design and preparation of chalcogenide glass doublet lenses for infrared optical system

Abstract

In the realm of infrared (IR) optics, IR doublet lenses have garnered a lot of attention due to their ability to correct for aberrations. A new series of Ge₁₅Se_85‒xTe_x (5 ≤ x ≤ 30) chalcogenide glass was developed to possess similar glass transition temperature, excellent thermal stability, and large refractive index variation, which enable them to be a good glass material catalog for IR doublet lenses. First, six glasses were successfully molded into one using thermal bonding, and its refractive index distribution was investigated. To lower the dispersion of IR doublet lenses, the two most suited materials were chosen from the above material library on the basis of their Abbe number (ν) and dispersion (p) value. With the created doublet lenses, an IR optical system with a wavelength of 3‒12 µm was designed. The system's modulation transfer function curve demonstrated its good imaging performance (>0.3 @ 24 cycles/mm). Through additional optical design, we discovered that modifying the curvature of the internal interface of the IR doublet lens could reduce the length of the optical system by 17% while maintaining its performance.