NIM-2 -- A Near Infrared Imaging Vector Magnetograph


NIM-1 is a spectrograph-based Stokes polarimeter for measuring the strength and orientation of magnetic fields in the solar photosphere using two Zeeman-sensitive Fe I lines (g = 3 and g_geff = 1.53) near 1565 nm. NIM-2, now under construction, also uses these spectral lines but is based on a high-resolution Fabry-Perot etalon. NIM-2 will eliminate the image scanning and consequent spatial distortions of NIM-1 and will be compact and light enough to serve as a prototype for balloon or space instruments. The Queensgate etalon will provide a spectral resolving power of 10(5) over a 1-nm free spectral range. The initial detector will be the 256(2) InSb array shared with NIM-1, but NIM-2 is designed to accommodate a 512(2) or 1024(2) ``Aladdin’’ InSb array. The data system, also shared with NIM-1, is being upgraded to handle the faster switching speed ( åisebox-0.5ex~ 8 ms) of improved liquid- crystal variable retarders. NOAO is operated for the NSF by the Association of Universities for Research in Astronomy. Near- infrared magnetometry at NSO is supported by the the NASA Space Physics Division through the SR&T program in solar physics.

American Astronomical Society Meeting Abstracts #188