Computational imaging system for extended depth of field

Theories are described for an integrated computational imaging system that combines a logarithmic aspheric imaging lens with maximum entropy digital processing to extend the depth of field 10 times over that of a conventional lens and to provide near diffraction-limited resolution. Different types of logarithmic aspheres are derived which are circularly symmetric lenses with controlled continuous radial variation of focal length. The details of an iterative maximum entropy algorithm are also presented. The properties of convergence and speed of the algorithm are greatly improved by introducing a metric parameter properly to adjust the weight of different pixel values of the recovered picture in each loop.; The lenses are fabricated using an OptiPro model SX50 computer-controlled grinding machine and a QED magneto-rheological finisher Q22Y to an overall accuracy of the order of one-tenth of a wavelength. The experimental results show the success of the combined system to extend the depth of field of the imaging system.