Diffractive lens in 8- to 10-μm forward-looking infrared system

Abstract

We realize for the first time a forward-looking IR (FLIR) sys- tem using a diffractive optical element (DOE) in its optics made of ger- manium in the 8- to 10-mm IR wavelength. We describe the design and the performance of the DOE optics. The IR diffractive lens made of ger- manium is proposed to correct the axial chromatic aberration in optics of the FLIR system. Compared with conventional optics of an FLIR system the optics using a DOE singlet instead of ZnSe achromat, we have a DOE system modulation transfer function (MTF) that is almost equal to the conventional one. The DOE singlet instead of ZnSe achromat ap- pears to be enough to compensate for the chromatic aberration of the optical system. Using the DOE system, the numbers of lens elements, the mass, and the cost are reduced. © 2002 Society of Photo-Optical Instrumen- tation Engineers. (DOI: 10.1117/1.1487365)