Li, C.L. Corbett, W.J. Mitsuhashi, T.M. JACoW Geneva, Switzerland 978-3-95450-176-2 10.18429/JACoW-IBIC2015-TUPB021 English 364-368 TUPB021 polarization radiation diagnostics synchrotron synchrotron-radiation Contribution to a conference proceedings 2016 2016-01 http://dx.doi.org/10.18429/JACoW-IBIC2015-TUPB021 http://accelconf.web.cern.ch/AccelConf/IBIC2015/papers/tupb021.pdf Synchrotron radiation has the well-known property of horizontal field polarization in the midplane with increasingly elliptical polarization in the vertical plane. By measuring the beam intensity transmitted through a linear polarizer, it is possible to characterize the beam polarization state, determine the Stokes' parameters and solve for the beam polarization ellipse in the visible portion of the SR spectrum. The results can be compared with Schwinger's equations for synchrotron radiation taking into account the effect of extraction mirrors.