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AbstractThe Stokes method provides a seminal method for the determination of a state of polarization of a beam of light using measurable quantities. This paper presents a methodology for the rapid acquisition of the four Stokes parameters. We have been able to acquire images at the rate of 500 images per second using a high speed video camera. Using the high speed video camera, an optical chopper, a computer system containing a frame grabber and software to coordinate all elements of the system, the four Stokes parameters have been acquired in 6 milliseconds. Included in this paper is a description of all elements of the system, the calibration of the camera and polarization elements, the design of the optical chopper
This paper presents a methodology to obtain polarization profiles using a commercial off-the-shelf (COTS) digital camera. It contains calibration techniques to ensure robust and accurate determination of the Stokes parameters and the system polarization state. It calculates the Stokes parameters for each scene pixel along with the degree of polarization, azimuth, and ellipticity angles for each of the RGB channels. A detailed calculation shows that the quasimonochromatic approximation for the wavelength dependence of the quarterwave plate can be extended to include the broadband RGB channels. A simple and inexpensive camera calibration converts RGB values to optical density and then to relative intensity values. An analysis is presented for the wavelength-dependent response of the tuned zero-order quartz quarterwave retarder, the broadband RGB channels, and the fourth Stokes parameter. The noise characteristics of the digital camera are analyzed along with a detailed calibration of the imagery for target characterization applications. An extensive validation process, using white light, compares calculated theoretical results with the empirical results from the COTS camera. A RGB pseudocoloring scheme, related to the Poincaré sphere, is introduced for the visualization of polarization parameters of daylight scenes.
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