Construction of an Infrared Spectropolarimeter

This award will support construction of a high accuracy, high sensitivity spectropolarimeter for use from 1 to 4 micrometers. The instrument will incorporate both cold and warm rotating waveplates with a cold internal polarizer. The effective resolving power will be R=180 and instrumental polarization will be less than 0.1%. The instrument will incorporate a 16 element InSb detector array and will be background limited at this resolution at all wavelengths from 1 to 4 micrometers. Scientifically, this award will target interstellar dust features, comets, very dusty evolved stars and nuclei of active galaxies for study with this instrument. Infrared spectropolarimetry will provide important information on the relationships between silicate and carbon compounds in interstellar dust and on the environment of interstellar dust that exhibits emission from carbonaceous compounds. Infrared spectropolarimetry will also allow us to probe the geometry and the spatial relationships between emission mechanisms in the coma of comets, the circumstellar shells of dusty stars, and the nuclei of active galaxies.