spectropolarimetry

Spectropolarimetry is the measurement of EMR polarization by wavelength. Light that is not monochromatic (i.e., has a mix of wavelengths) may have one kind and amount of polarization at one wavelength and at some other wavelength have another kind/amount. Spectropolarameters (instruments to carry out spectropolarimetry) are used on ground telescopes, and spacecraft including telescopes and planet exploration missions. Applications include detecting and mapping magnetic fields (by working out the Faraday rotation) such as those around the Sun, and working out characteristics of the source of reflected or scattered EMR, such as from a planetary nebula, or an active galactic nucleus.

My understanding is that an astronomical spectropolarimeter passes light through the sort of filter used in a polarimeter (that allows only a specific polarity of light to pass through, one type being a Wollaston prism), and also through a disperser (as found in a spectrometer), the two in series. (My impression is that the polarization-filtering is typically first in this series.) The result is recorded on a CCD, and multiple such observations varying the filtered polarization gives more-complete data on the incoming light's polarization characteristics.

I suspect that for spectropolarimetry of the Sun's corona, specialized techniques are likely used, attempting to record changes in spectropolarimetry data over relatively-short time periods. The aim would be to gather the data quickly, to support a rapid cadence. Furthermore, accomplishing all this and also covering both spatial dimensions would be of interest, if there is a way to do that, and compromises may be necessary to balance these conflicting goals.