Comparison between a new holographically generated complex filterand the binary phase filter for depth of field extension

摘要

To improve the depth of field in imaging systems, we propose a new method for designing pupil filters with the classicalapproach used for computer-generated holograms. This method allows us to calculate a complex amplitude/phase filterin order to obtain a desired distribution of intensity along the optical axis, and thus the desired depth of field. We will compare our complex filter with binary-phase filters, which are one of the different methods alreadyinvestigated to improve the depth of field in imaging applications. This study will reveal that the complex filter is aninteresting alternative for applications where very low fluctuations of the amplitude distribution along the optical axis arerequired. It is indeed as energy-efficient as a pure phase filter even with a non negligible absorption. It also ensures toprecisely tailor the shape of the focal line of an imaging lens, as the decrease of intensity is sharper outside the regions ofinterest than with the binary-phase filter. Moreover, it also benefits from lower sidelobes. With these characteristics, thisnew complex filter will be suitable particularly for 3D imaging applications.