Abstract
We have measured the optical response of prototype detectors for SAFARI, the far-infrared imaging spectrometer for the SPICA satellite. SAFARI’s three bolometer arrays, coupled with a Fourier transform spectrometer, will provide images of a 2′×2′ field of view with spectral information over the wavelength range 34–210 μm. Each horn-coupled bolometer consists of a transition edge sensor (TES), with a transition temperature close to 100 mK, and a thin-film Ta absorber on a thermally-isolated silicon nitride membrane. SAFARI requires extremely sensitive detectors (NEP∼2×10−19 W/\(\sqrt{\mathrm{Hz}}\)), with correspondingly low saturation powers (∼5 fW), to take advantage of SPICA’s cooled optics. To meet the challenge of testing such sensitive detectors we have constructed an ultra-low background test facility based on a cryogen-free high-capacity dilution refrigerator, paying careful attention to stray-light exclusion, shielding, and vibration isolation. For optical measurements the system contains internal cold (3–30 K) and hot (∼300 K) black-body calibration sources, as well as a light pipe for external illumination. We discuss our measurements of high optical efficiency in prototype SAFARI detectors and describe recent improvements to the test facility that will enable us to test the full SAFARI focal-plane arrays.
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References
B. Swinyard et al., Exp. Astron. 23, 193 (2008)
B. Jackson et al., IEEE Trans. Terahertz Sci. Technol. 2, 1 (2011)
K.D. Irwin, G.C. Hilton, in Cryogenic Particle Detection, ed. by C. Enss (Springer, Berlin, 2005), pp. 81–97
P. Khosropanah et al., Proc. SPIE 8452, 845209 (2012)
Leiden Cryogenics BV. http://www.leidencryogenics.com
M.D. Audley et al., J. Low Temp. Phys. 167, 208 (2012)
M.D. Audley et al., Proc. SPIE 8452, 84520B (2012)
Acknowledgements
We thank Douglas Griffin of the Rutherford Appleton Laboratory for supplying the feedhorn. The detectors and feedhorn used in this work were originally produced for ESA TRP contract No. 22359/09/NL.CP, TES Spectrometer.
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Audley, M.D., de Lange, G., Ranjan, M. et al. Measurements of the Optical Performance of Prototype TES Bolometers for SAFARI. J Low Temp Phys 176, 755–760 (2014). https://doi.org/10.1007/s10909-013-0984-5
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DOI: https://doi.org/10.1007/s10909-013-0984-5