Systematic effects induced by a flat isotropic dielectric slab
arXiv:astro-ph/0602588 · doi:10.1364/AO.45.005168
Abstract
The instrumental polarization induced by a flat isotropic dielectric slab in microwave frequencies is faced. We find that, in spite of its isotropic nature, such a dielectric can produce spurious polarization either by transmitting incoming anisotropic diffuse radiation or emitting when it is thermally inhomogeneous. We present evaluations of instrumental polarization generated by materials usually adopted in Radioastronomy, by using the Mueller matrix formalism. As an application, results for different slabs in front of a 32 GHz receiver are discussed. Such results are based on measurements of their complex dielectric constant. We evaluate that a 0.33 cm thick Teflon slab introduces negligible spurious polarization ( in transmission and in emission), even minimizing the leakage ( from to Stokes parameters, and viceversa) and the depolarization ().
Accepted for pubblication in Applied Optics, 32 pages, 14 figures (N. 37 ".png", ".bb"). Better quality figures available from author upon request
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