| We describe two phase plates to extend the depth of field of incoherent hybrid imaging systems, and a phase plate to reduce the depth of field of incoherent hybrid imaging systems. A hybrid imaging system is a modified standard imaging system with a digital post-processing step. In such a system, the imaging process is divided between a physical optical module and a mathematical module.; The first phase plate is a logarithmic plate to extend the depth of field of a system with a rectangular aperture. The second phase plate is a two dimensional, non-separable plate to extend the depth of field of a system with a circular aperture. By introducing either plate at the exit pupil and digitally processing the detector's output, the depth of field is extended by an order of magnitude more than the Hopkins defocus criterion.; We define a new metric to quantify the blurring of a defocused image, which we use to design a phase grating to reduce the depth of field, thereby increasing the axial resolution, of a system with a rectangular aperture. By introducing this grating at the exit pupil and digitally processing the detector's output, the depth of field is reduced by more than a factor of two. |
