A smart camera is studied that combines the blurring logarithmic asphere lens and maximum entropy processing to extend the depth of field 10 times over that of a conventional lens and to provide near diffraction-limited performance. For this camera, a circularly symmetric logarithmic lens with radially varying focus length provides an image with distance invariant blur; a newly developed digital deconvolution technique, the accelerated maximum entropy processing, is thereafter applied to recover the sharp image providing an extended depth of field. Three types of logarithmic aspheres are described together with the effect of aperture apodizations. We show that the central obscuration of the aperture improves the overall performance of the smart camera, especially the near distance performance. The performance of the maximum entropy processing is greatly improved by introducing a new metric parameter into the algorithm. In the presentation, I will demonstrate the novel maximum entropy algorithm that has been devised, and also demonstrate the lens manufacturing technique of magnetorheological finisher that we used.
"Smart camera with extended depth of field", Proc. SPIE 6024, ICO20: Optical Devices and Instruments, 602424 (9 December 2005); doi: 10.1117/12.666949; https://doi.org/10.1117/12.666949