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Variable-delay Polarization Modulators (VPMs). D. Chuss, G. Novak 7/27/07. Variable-delay Polarization Modulator(VPM). Advantages of VPMs. Can be made intrinsically broadband Can measure circular polarization- a potentially useful systematic check of instrument
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Variable-delay Polarization Modulators (VPMs) D. Chuss, G. Novak 7/27/07
Advantages of VPMs • Can be made intrinsically broadband • Can measure circular polarization- a potentially useful systematic check of instrument • Used in reflection- no dielectrics to introduce differential loss. • Employs small, linear motions rather than large circular ones- A reliability issue.
Hertz/SMTO NASA/GSFC: D. Benford, D. Chuss, M. Jackson, H. Moseley, J. Staguhn, G. Voellmer, E. Wollack Northwestern University: G. Novak, M. Krejny (GSRP) University of Arizona: C. Walker, C. D. d’Aubigny, C. Kulesa, D. Golish University of Chicago- R.F. Loewenstein Using a pair of VPMs, we have integrated the 350 micron, 32 pixel polarimeter Hertz onto the SMTO in Arizona.
QVI 1: Selects Between Q & U (Grid wires at 22.5 degrees) QVI 2: Toggles Roles of detectors (Q->-Q) (Grid wires at 45 degrees)
Instrumental polarization- preliminary result Q=0.8 +/- 0.3% U=0.01 +/- 0.02% Data taken 4/24/07 Jupiter 29 observations tau~0.07, el=33 deg.
VPM “Walkoff” Systematic • When placed at or near an image plane, the image formed by each polarization will be shifted relative to one another.
Density Matrices Unpolarized Radiation Field Walkoff Polarization Modulation
Kilo-pixel Backshort-Under-Grid TES Arrays D. Chuss 7/27/07
Basic TES Circuit Allen et al. (2006) Benford et al. IJIRMMW
Time-Domain Multiplexing Irwin et al. (2004)
GSFC BUG Architecture Allen et al. (2006) Staguhn et al. (2006)
Pixel Frames Allen et al. (2006)
Large Format Arrays • 32 x 40 pixel arrays proposed as a continuation (ROSES) • These will be mated to the SCUBA MUXes • Pending funding, expected readiness date: late 2009 • Warm Electronics- suggest UBC source