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Proceedings Paper

A test setup for the characterization of far-infrared filters under cryogenic conditions
Author(s): Stephan M. Birkmann; Ulrich Grözinger; Jutta Stegmaier; Oliver Krause; Eckhard Pitz; Dietrich Lemke
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Paper Abstract

The characterization and calibration of far-infrared (FIR) detectors is a delicate task that requires good knowledge of the incident flux and its spectral composition. In many test setups the FIR flux to the detectors is provided by means of an external or internal black body and a set of cold attenuation, band pass, and blocking filters. For scientific instruments (e.g. PACS aboard ESA's Herschel satellite) band pass and blocking filters are used to achieve the desired spectral throughput either as order sorting filters in spectrometers or for selecting a wavelength range in imaging cameras. In all cases a detailed knowledge of the spectral transmittance of the used filters is mandatory for an accurate calibration of the system. We have build a test platform that allows to measure the transmission of cold (T ~ 4K) filters in the far-infrared. The setup uses a dual grating monochromator with excellent spectral purity and a resolution up to 800, which is operated under a dry nitrogen atmosphere to eliminate water vapor absorption bands. An Si-bolometer is used as detector and is read out by a cryogenic low noise trans-impedance amplifier circuit with common mode rejection and a warm electronics using a lock-in amplifier and a 22 bit analog-to-digital converter. A cryogenic filter slider in the setup allows for differential measurements between filters and the use of cold order sorting filters. We present initial results for FIR cut-on and attenuation filters, demonstrating that our setup is suited to measure transmissions as low as 10-4 over the covered wavelength range.

Paper Details

Date Published: 16 June 2006
PDF: 11 pages
Proc. SPIE 6275, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III, 62750S (16 June 2006); doi: 10.1117/12.671121
Show Author Affiliations
Stephan M. Birkmann, Max-Planck-Institut für Astronomie (Germany)
Ulrich Grözinger, Max-Planck-Institut für Astronomie (Germany)
Jutta Stegmaier, Max-Planck-Institut für Astronomie (Germany)
Oliver Krause, Max-Planck-Institut für Astronomie (Germany)
Eckhard Pitz, Max-Planck-Institut für Astronomie (Germany)
Dietrich Lemke, Max-Planck-Institut für Astronomie (Germany)

Published in SPIE Proceedings Vol. 6275:
Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III
Jonas Zmuidzinas; Wayne S. Holland; Stafford Withington; William D. Duncan, Editor(s)

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