Athermalization of infrared optical system through wavefront coding

Owing to the thermal effect of optical components, it has been challenging for conventional infrared optical imaging system to work in a large temperature range. Wavefront coding technique has been shown to greatly increase tolerance to manufacturing inaccuracies and various defocus, particularly thermal defocus. In this paper, we develop an entirely new infrared imaging modality in 3.7 ∼4.8μm waveband, realized with a secondary imaging structure, a non-rotationally symmetric phase mask and a cooled infrared focal plane arrays. The proposed system offers the ability to overcome the temperature limitations of conventional infrared system as well as effectively eliminate the thermal aberration. Proof-of-concept results demonstrate significantly our athermalized optical system perform high-quality images in the operation temperature range of −40 °C to 70 °C.