Patent ID: 7218448

Claim:
An optical system for increasing a depth of field, the optical system characterized at least by an ambiguity function and a point spread function (PSF), which ambiguity function is a function of a normalized spatial frequency parameter u and a vertical variable v related to a misfocus parameter ψ, and which PSF is at least a function of the misfocus parameter ψ, the optical system comprising: a plastic element configured for imaging light from an object to form an image, the light including at least phase and amplitude and the plastic element being configured to maintain the amplitude of light passing through the plastic element; a mask optically connected with the plastic element and configured for altering the phase of the light while maintaining the amplitude of the light passing through the mask such that a main lobe of the ambiguity function is broader in v for a given value of u over an optical bandpass of the imaging system, and the PSF has a functionally different form for a given value of ψ, in comparison to a main lobe of an ambiguity function, a PSF and the optical bandpass, respectively, characterizing the optical system without the mask for those given values of u and ψ, over a range of object distances between the object and the plastic element; and a signal processor configured for removing from the image, in accordance with the PSF, an imaging effect induced by the altering of the phase by the mask.