To extend the depth of field by using the asymmetrical phase mask and its conjugation phase mask in wavefront coding imaging systems

In this paper, we present a method for combining an asymmetrical phase mask and its conjugation phase mask to produce the point spread function of a wavefront coding imaging system, which has the defocus invariant characteristic of the asymmetrical phase mask and symmetric characteristic through an orthogonal axis pair of the symmetrical phase mask. Simulation results for comparing the wavefront coding imaging system with combining the sinusoidal phase mask and its conjugation phase mask and a traditional imaging system for a clear aperture without any phase mask are presented. Comparative results indicate that the wavefront coding imaging system combined with the sinusoidal phase mask and its conjugation phase mask has an imaging performance invariant over a wide range of defocus.