Kyle Helson with John Ruhl

Sapphire Half-Wave Plate Characteristics

The polarization of the cosmic microwave background radiation (CMB) contains imprints of gravity waves from the early universe. The Spider telescope is a balloon-borne telescope designed to extensively investigate this polarization. Using six rotating sapphire half-wave plates, the light from the CMB will be rotated before being measured by six separate bolometers. Characterization of these half-wave plates, along with their quartz anti-reflective coatings is necessary for their implementation. Spectra will be taken using a Fourier Transform Spectrometer and the ACBAR cryogenic test dewar. Data will be analyzed to determine whether the HWP’s meet specifications.