Abstract: An afocal beam system corrects excess diffraction from phase error in microelectromechanical mirror offsets. One invention aspect interposes an opposing phase difference, between rays reflected at adjacent mirrors, varying the difference with mirror angle to make it roughly an integral number of waves. Mirror-array (not one-mirror) dimensions limit diffraction. Another aspect sharpens by generating and postprocessing signals to counteract phase difference. A third has, in the optical path, a nonlinear phase-shift device introducing a phase shift, optically convolves that shift with others from mirrors, then deconvolves to extract unshifted signals. A fourth varies mirror position in piston as a function of mirror angle to hold phase difference to an integral number of waves. A fifth aspect has, in the path, at least one delay element—whose delay varies as a function of mirror angle. A sixth has another mirror array in series with the first, matching their angles to introduce opposing phase difference.

Abstract: Preferably a sensor receives a print image from an authorized person to form a template, and from a candidate to form test data. Power spectral density (PSD) data for the template and candidate are compared, to read out rotation & dilation; these are used to adjust the template or candidate preparatory to a correlation to find translation. After applying the translation, and refinement of the rotation and dilation, normalized spatial correlation values (NSCVs) are used as a measure of quality of the match—and thresholded to make an early rejection or acceptance decision in very clear cases. Where the question is closer, isomorphic adjustment is applied to the entire template or candidate for a fairer comparison in their overlap area. Such comparison proceeds by the same type of PSD analysis—but for multiple subregions in the overlap area. Resulting NSCVs are averaged to obtain a measure of quality of the match, which again is thresholded for a final decision in the closer cases.

Abstract: Preferably a sensor receives a print image from an authorized person to form a template, and from a candidate to form test data. Power spectral density (PSD) data for the template and candidate are compared, to read out rotation & dilation; these are used to adjust the template or candidate preparatory to a correlation to find translation. After applying the translation, and refinement of the rotation and dilation, normalized spatial correlation values (NSCVs) are used as a measure of quality of the match—and thresholded to make an early rejection or acceptance decision in very clear cases. Where the question is closer, isomorphic adjustment is applied to the entire template or candidate for a fairer comparison in their overlap area. Such comparison proceeds by the same type of PSD analysis—but for multiple subregions in the overlap area. Resulting NSCVs are averaged to obtain a measure of quality of the match, which again is thresholded for a final decision in the closer cases.

Abstract: Local data about the ocean surface and what is above it are used to improve public radio and TV weather reporting; to improve small-craft ocean traffic safety in view of local precipitation, wind, icebergs, or cloudiness; or to improve performance of wind-sensitive sound-receiving apparatus. (As to weather reporting, one mechanism is in effect a calibration of simultaneous satellite-based data. As to acoustic receivers, the mechanism is orienting receivers to the wind, to minimize wind-noise pickup.) These functions are based on observing, from a distance below the surface, light intensities of many areas of the irregular water surface. From these intensities surface-slope magnitudes and orientations are estimated; analysis of this information enables a quantitative, dynamic representation of the water surface itself. From this model in turn, the conditions enumerated earlier are inferred.