Stokes Polarimetry with the Near Infrared Magnetograph --- Telescope Polarization Effects
Session 123 -- Solar Magnetic Field and Solar Variabilty
Oral presentation, Thursday, 12, 1995, 2:00pm - 3:30pm

[123.02] Stokes Polarimetry with the Near Infrared Magnetograph --- Telescope Polarization Effects

D. Rabin (NSO/NOAO)


\NIM\ produces spatial images of magnetic field properties in the low photosphere from polarized spectra of the $g = 3$ line Fe~I 6388.64~\kayser\ (1.5648~\micron). Designed initially for circular polarimetry, \NIM\ can now acquire full Stokes information. I discuss the approximate polarization transfer (Mueller) matrix for \NIM\ as used at the McMath-Pierce Telescope and compare it with the transfer matrix at visible wavelengths. Although telescope polarization effects are generally smaller in the infrared, in one respect the infrared requires careful treatment. In the visible, the net linear polarization due to the Zeeman effect is often small enough compared to circular polarization that linear-to-circular instrumental crosstalk is unimportant. In the infrared, the Zeeman components are usually so strongly split that the linearly polarized Stokes components ($Q$ and $U$\/) are comparable in magnitude to the circular component ($V$\/).

This work has been supported by the NASA SR\&T program in solar physics.