Optical design study in the 3-12 um spectral band with gradient-index materials

摘要

A design study is conducted in the 3-12 μm wavelength band for an F/2.5, 15.2 degree full field of view, 66 mm focal length imaging system. A survey of preferred homogeneous materials and their chromatic properties which transmit over the full wavelength band is explored. A survey of GRIN materials is also explored, which includes zinc selenide zinc sulfide GRIN, and chalcogenide GRIN from NRL and Schott. GRIN is able to expand the infrared glass map which is otherwise relatively small. The design space is explored over three and four homogeneous elements as well as one GRIN and two homogeneous elements. The three element design with the addition of GRIN results in a better balance between the two bands and is nearly diffraction-limited. The three element design can be reduced to two GRIN elements which has comparable performance to the homogeneous three element design.