Optical Characterization of the SPT-3G Camera

• Published in: Journal of low temperature physics Vol. 193; no. 3-4; pp. 305 - 313
• Main Authors: Pan, Z., Ade, P. A. R., Ahmed, Z., Anderson, A. J., Austermann, J. E., Avva, J. S., Thakur, R. Basu, Bender, A. N., Benson, B. A., Carlstrom, J. E., Carter, F. W., Cecil, T., Chang, C. L., Cliche, J. F., Cukierman, A., Denison, E. V., de Haan, T., Ding, J., Dobbs, M. A., Dutcher, D., Everett, W., Foster, A., Gannon, R. N., Gilbert, A., Groh, J. C., Halverson, N. W., Harke-Hosemann, A. H., Harrington, N. L., Henning, J. W., Hilton, G. C., Holzapfel, W. L., Huang, N., Irwin, K. D., Jeong, O. B., Jonas, M., Khaire, T., Kofman, A. M., Korman, M., Kubik, D., Kuhlmann, S., Kuo, C. L., Lee, A. T., Lowitz, A. E., Meyer, S. S., Michalik, D., Montgomery, J., Nadolski, A., Natoli, T., Nguyen, H., Noble, G. I., Novosad, V., Padin, S., Pearson, J., Posada, C. M., Rahlin, A., Ruhl, J. E., Saunders, L. J., Sayre, J. T., Shirley, I., Shirokoff, E., Smecher, G., Sobrin, J. A., Stark, A. A., Story, K. T., Suzuki, A., Tang, Q. Y., Thompson, K. L., Tucker, C., Vale, L. R., Vanderlinde, K., Vieira, J. D., Wang, G., Whitehorn, N., Yefremenko, V., Yoon, K. W., Young, M. R.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.11.2018; Springer Nature B.V; Plenum Press
• Subjects: beam; Big Bang theory; Bolometers; Broadband; Characterization and Evaluation of Materials; Condensed Matter Physics; Cosmic microwave background; Detectors; Fourier transform spectrometer; Fourier transforms; Frequencies; Frequency bands; Low temperature physics; Magnetic Materials; Magnetism; Optical efficiency; Optical properties; Physics; Physics and Astronomy; Polarization; Sensor arrays; Sensors; South Pole; time constant; transition-edge sensor; Transition-edge sensor; Beam; Polarization; Frequency bands; Cosmic microwave background; Fourier transform spectrometer; Optical efficiency; Time constant
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-018-1935-y

The third-generation South Pole Telescope camera is designed to measure the cosmic microwave background across three frequency bands (centered at 95, 150 and 220 GHz) with ∼  16,000 transition-edge sensor (TES) bolometers. Each multichroic array element on a detector wafer has a broadband sinuous antenna that couples power to six TESs, one for each of the three observing bands and both polarizations, via lumped element filters. Ten detector wafers populate the detector array, which is coupled to the sky via a large-aperture optical system. Here we present the frequency band characterization with Fourier transform spectroscopy, measurements of optical time constants, beam properties, and optical and polarization efficiencies of the detector array. The detectors have frequency bands consistent with our simulations and have high average optical efficiency which is 86, 77 and 66% for the 95, 150 and 220 GHz detectors. The time constants of the detectors are mostly between 0.5 and 5 ms. The beam is round with the correct size, and the polarization efficiency is more than 90% for most of the bolometers.