Abstract:
Embodiments of an active or laser polarimeter are disclosed that transmit multiple independent and tunable temporally-multiplexed polarization states and record or image, at video rates if necessary, the polarized intensity or irradiance reflected or transmitted by objects illuminated by those states, and apply the recorded data to material and/or object classification and recognition using classification algorithms that exploit features of polarization signatures dependent on material type, texture, and/or object shape. The polarimeter also generally records and utilizes one or more passive polarization measurements in order to realize a hybrid active-passive polarimeter. The polarimeter channels are configured and tuned to access multi-dimensional signature spaces specified by existing signature models and/or measurements, with polarization-modulator settings derived by a newly-disclosed subspace-projection algorithm that maximizes a target contrast parameter. Multiple independent polarization channels allow the new polarimeter to outperform conventional two-channel polarimeters, while the subspace-projection algorithm allows the number of channels to be minimized in order to minimize sensor size, weight, and power (SWaP) and maximize speed. Multiple channels are realized by multiplexing among independent transmitter polarization states with one or more high-speed multiplexers, in one embodiment a set of fold-mirror assemblies in the transmitter among which the laser beam is switched by one or more galvanometer scanners fitted in one embodiment with a newly-disclosed composite mirror. The method for material and object classification and recognition includes the maximally-biased classifier derived by the subspace-projection algorithm applied to a single target Mueller matrix, and methods to generalize the classifier.
Abstract:
Polarized pixelated filter sub-array is reconfigured to reduce sensitivity to misalignment. The condition number increases more slowly than the standard polarized pixelated filter sub-array as the misalignment increases. In different embodiments, the filter sub-array is configured such that the condition number has a finite bound at ½ pixel misalignment. The angular values of the polarizer filter array are determined to minimize the sensitivity of the condition number of the data reduction matrix to misalignment. This can be achieved by selecting angular values that minimize the expected value of the condition number E(CN) over the range of misalignment.
Abstract:
An apparatus and system for use in determining location of a celestial body are presented. The apparatus comprises: a polarizer comprising an array of polarized light filter cells and a light sensor array. The array of polarized light filter cells comprises at least a first polarization direction and a second polarization direction different from said first polarization direction. And the polarizer thereby produces polarized light of at least first and second different polarizations. The light sensor array is configured to receive the polarized light from the polarizer and produce data indicative of a pattern of at least one of light polarization intensity and direction. The pattern is indicative of at least one of azimuth and elevation of the celestial body to be located.
Abstract:
The invention relates to a sensor assembly (1) for capturing spatially resolved photometric data comprising a sensor unit (10), a controllable shutter assembly (20), which is arranged in front of the sensor unit (10) and by means of which an incidence of light on the sensor unit (10) can be controlled in dependence on direction, and an evaluating unit (30) for evaluating the information output by the sensor unit (10) and calculating spatially resolved brightness information, wherein the sensor unit (10) has at least two sensor segments (11), with which different combinations of color and polarization filters (12, 13) or spectrometers are associated, and wherein the evaluating unit (30) is designed to supplement the brightness information with additional photometric data on the basis of the signals output by the various sensor segments (11).