The wavefront of a light wave passing through the camera system is modulated using optical elements that introduce a spatially varying optical path length. The modulating elements must be placed at or near the plane of the aperture stop or pupil so that the same modulation is introduced for all field angles across the field-of-view. This modulation corresponds to a change in complex argument of the
pupil function of such an imaging device, and it can be engineered with different goals in mind: e.g. extending the depth of focus.
Linear phase mask Wavefront coding with linear phase masks works by creating an optical transfer function that encodes distance information.
Cubic phase mask Wavefront Coding with cubic phase masks works to blur the image uniformly using a cubic shaped
waveplate so that the intermediate image, the optical transfer function, is out of
focus by a constant amount.
Digital image processing then removes the blur and introduces noise depending upon the physical characteristics of the processor.
Dynamic range is sacrificed to extend the depth of field depending upon the type of filter used. It can also correct
optical aberration. The mask was developed by using the
ambiguity function and the
stationary phase method ==History==