Infrared imaging-passive thermal compensation via a simple phase mask

Infra-Red (IR) imaging systems are now in wide use, due to new technologies that enable manufacturing of low cost systems. Most of the IR optical materials (Germanium in particular) are very sensitive to temperature variations. This sensitivity is reflected in a temperature dependent refractive index, which in turn affects the focal length and results in strong deterioration of the image quality with temperature variations. The thermal sensitivity can be compensated using a passive all-optical phase mask. IR imaging system incorporating such simple phase mask is hereby proposed and analyzed, followed by simulation results.