Extended depth-of field imaging by both radially symmetrical conjugating phase masks with spatial frequency post-processing

In this paper, we propose a method to improve the contrast of image by using both radially symmetrical conjugating phase masks. The method is based on the generation of synthetic optical transfer function (OTF) from OTFs of both radially symmetrical conjugating phase masks. Both quartic phase mask (QPM) and its conjugating phase mask (cQPM) are used as an example. Two images are captured by QPM and cQPM. In Fourier domain, a combination of both QPM and cQPM produces the improvement of the contrast of images in all spatial frequency positions. The simulation results demonstrated that the contrast improvement of image of proposed method is obtained.