Application of the polarization-holographic imaging Stokes spectropolarimeter in astronomy

Abstract

An innovative polarization-holographic imaging Stokes spectropolarimeter is presented. The main analyzing unit of such a polarimeter is the integral polarization-holographic diffraction element, which enables the complete analysis of the polarization state of incoming light to be carried out in real-time. It decomposes the incoming light into diffraction orders, the intensities of which vary depending on the polarization state of the light source. After the simultaneous diffraction order intensity measurements of the corresponding points or areas in the diffraction orders, we get the realtime Stokes images of the light source, which allows determining the entire polarization state of a point or extended space object for different spectral regions and variable polarization. A working aperture can be from 0.5 cm up to 5 cm in diameter. The results of studies on improving the stability and diffraction efficiency of the element are presented. Measurements of the polarization state by the standard star were carried out to calibrate the spectropolarimeter. Polarimetric measurements of some astronomical objects have been carried out. The resulting errors are better than 10 -2 . The polarization-holographic imaging Stokes spectropolarimeter has no mechanically moving or electrically tunable optical elements, has no internal reflections, and is universal, compact, cost-effective, and lightweight.