PSF model for diffractive optical elements with improved imaging performance in dual-waveband infrared systems.

Single-layer diffractive optical elements (SLDOEs) have advantages in terms of configuration, fabrication, range of angles and cost; however, the diffraction efficiency decreases sharply with wavelength deviating from the design wavelength, especially for dual-waveband imaging, causing apparent image blur. We propose a point spread function (PSF) model affected by the diffraction efficiency, which is called PSF, and a method of restoring the blurred image to improve imaging performance in dual-waveband infrared systems with an SLDOE. Then, a design example of cooled MWIR and LWIR is presented. Furthermore, imaging simulations with different grades noises and restorations are conducted. Results reveal that the PSF model can significantly improve the image blur caused by the decreased diffraction efficiency.