PSF engineering with variable logarithmic phase plates for the extended depth of field

Abstract

Shallow depth of field in imaging systems with high numerical apertures results in images with in- and out-of-focus regions. Therefore, methods to enhance the depth of field are of special interest. In point spread function engineering, a custom phase plate is designed for each system to reduce sensitivity to defocus and thereby extend depth of field. In this paper, we present a method that enables extended depth of field for a range of numerical apertures using a freeform variable logarithmic phase plate pair. We leverage a numerical design approach for the variable phase plate pair design, and explore phase plate optimization and performance by quantifying and comparing through-focus point spread function variation, and on- and off-axis performance for the designed phase plates.

Dynamic wavefront coding using deformable mirror

“…On the other hand, due to the mismatch between the PSF of the actual encoding process and the PSF of the image restoration process, there is an artifact effect in the restored image. Both of these factors will reduce the quality of the restored image, and become more serious with the increase of the phase mask intensity [13] . Thus, for a mask of a given intensity, there is a trade-off between the extended range of depth of field and the quality of image recovery.…”