Effect of point spread function position bias in wavefront coding infrared imaging system

Abstract

By an experimental finding, for a given radiant point source and a given infrared detector sampling, an optical point spread function (PSF) falling on different positions of an infrared detector focal plane array, will result in different measured PSFs. Those measured PSFs known as decoding kernels will further produce different decoded images. Therefore, this work explores the effect of PSF position bias on decoded images in a wavefront coding infrared imaging system. This paper theoretically analyzes the effect of PSF position bias on decoded images. A simulation is conducted for qualitatively evaluating the effect of PSF position bias on decoded images by mean structural similarity (MSSIM) index. Simulated results prove that the probability for MSSIM index greater than 0.75 is 91.38%, and that for less than 0.5 is only 1.22% but this minority seriously degrades the decoded images. We construct an experimental setup for capturing the raw PSF image at a random position and proposes a procedure to reduce the noise of a raw PSF image. The experimental result demonstrates the feasibility for measuring a PSF to achieve a decoded image with good quality.

Dynamic wavefront coding using deformable mirror

“…However, there are two main defects in this technology: noise amplification and artifact effect in the process of image restoration, which reduce the image quality and greatly limit the development and application of this technology. The artifact effect is mainly caused by a shift between the restored PSF and the encoded PSF, that is, the single target depth of field is designed for the panoramic depth expansion [5] . Therefore, the effect can be reduced by designing the system depth of field to vary freely with different scenes [6][7] .…”