High depth-of-focus integral imaging with asymmetric phase masks

Abstract

In this chapter, we address the problem of the limited depth-of-field and depth-of-focus of integral imaging systems. We first describe the origin of the problem in both the pickup and the reconstruction stages. Then we show how the depth-of-field/depth-of-focus can be significantly improved by placing an asymmetric phase mask in front of each lenslet. We apply this technique in the pickup as well as in the reconstruction stages, and we demonstrate that very out-of-focus objects can be resolved, at the price of a slight diffusion effect. Moreover, since the use of a phase mask preserves all the spectrum information within its passband, it is possible to apply a digital restoration step in order to eliminate the diffusion effect and retrieve clean images over a large range of distances. © 2009 Springer-Verlag New York.