Noise equalization in Stokes parameter images obtained by use of variable-retardance polarimeters

An imaging variable retardance polarimeter was developed and tested by Tyo and Turner [Proc. SPIE 3753, 214 (1999)]. The signal-to-noise ratio (SNR) i n the reconstructed polarization images obtained with this system varied fo r the four Stokes parameters. The difference in SNR is determined to be due to differences in the Euclidean lengths of the rows of the synthesis matri x used to reconstruct the Stokes parameters from the measured intensity dat a. I equalize (and minimize) the lengths of the rows of this matrix by mini mizing the condition number of the synthesis matrix, thereby maximizing the relative importance of each of the polarimeter measurements. The performan ce of the optimized system is demonstrated with simulated data, and the SNR is shown to increase from a worst case of -3.1 dB for the original setting s to a worst case of +5.0 dB for the optimized system. (C) 2000 Optical Soc iety of America OCIS codes: 260.5430, 230.5440.