On the emissivity of wire-grid polarizers for astronomical observations at mm-wavelengths

Schillaci, A.; Battistelli, E. S.; Gentilucci, Alessandro; Bernardis, P. de; Masi, S.

doi:10.1016/j.infrared.2013.01.009

Cited by 7 publications

(7 citation statements)

References 13 publications

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“…Due to the presence of many mirrors and optical elements (in case of the OLIMPO DFTS, 18 mirrors, 4 wire-grids and one HDPE lens) the emissivity of this grey body is not very small. In the literature we find an emissivity of 0.3% [22] for well polished aluminum mirrors at 150 GHz; the primary mirror and secondary mirror of OLIMPO have a somewhat rougher surface, so it is conservative to assume ∼ 1% emissivity; the HDPE lens has an emissivity ∼ 1% and the wire-grids < ∼ 2.5% [23].…”

Section: Common Mode Rejection and Sz Effect Ob-servationsmentioning

confidence: 80%

Common-mode rejection in Martin–Puplett spectrometers for astronomical observations at millimeter wavelengths

et al. 2015

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The Martin-Puplett interferometer (MPI) is a differential Fourier transform spectrometer that measures the difference between spectral brightness at two input ports. This unique feature makes the MPI an optimal zero instrument, able to detect small brightness gradients embedded in a large common background. In this paper, we experimentally investigate the common-mode rejection achievable in the MPI at millimeter wavelengths, and discuss the use of the instrument to measure the spectrum of cosmic microwave background anisotropy.

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Section: Common Mode Rejection and Sz Effect Ob-servationsmentioning

confidence: 80%

Common-mode rejection in Martin–Puplett spectrometers for astronomical observations at millimeter wavelengths

et al. 2015

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“…In order to estimate the UHMW emissivity, we build a setup like in [16]: a disk of UHMW, thickness of 10 mm, surrounded by a copper crown, which is, in turn, surrounded by an Aluminum ring, is suspended in air through some kevlar fibers, in order to thermally insulate the UHMW from its metal support.…”

Section: Emissivitymentioning

confidence: 99%

“…The output signal is demodulated through a Lock-in amplifier. Figure 6 shows a scheme of this setup, which is the same used in [25], in such a way that all the systematics are under control [16,25,26,27].…”

Section: Instrumental Setupmentioning

confidence: 99%

Ultra high molecular weight polyethylene: Optical features at millimeter wavelengths

D’Alessandro

Paiella

Coppolecchia

et al. 2018

Infrared Physics & Technology

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The next generation of experiments for the measurement of the Cosmic Microwave Background (CMB) requires more and more the use of advanced materials, with specific physical and structural properties. An example is the material used for receiver's cryostat windows and internal lenses. The large throughput of current CMB experiments requires a large diameter (of the order of 0.5m) of these parts, resulting in heavy structural and optical requirements on the material to be used. Ultra High Molecular Weight (UHMW) polyethylene (PE) features high resistance to traction and good transmissivity in the frequency range of interest. In this paper, we discuss the possibility of using UHMW PE for windows and lenses in experiments working at millimeter wavelengths, by measuring its optical properties: emissivity, transmission and refraction index.Our measurements show that the material is well suited to this purpose.

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“…In Table 1 we report the typical radiative background due to the room-temperature emissivity of mirrors (Bock et al 1995) and wire-grids in the spectrometer (Schillaci et al 2013), to the natural astrophysical background, and to residual atmosphere for a room-temperature implementation of the instrument on a good ground-based site and on-board of a balloon payload, and a cryogenic implementation on-board of a satellite.…”

Section: Sze Photometry and Spectrometrymentioning

confidence: 99%

Efficient differential Fourier-transform spectrometer for precision Sunyaev-Zel’dovich effect measurements

Schillaci

D’Alessandro

Bernardis

et al. 2014

A&A

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Context. Precision measurements of the Sunyaev-Zel'dovich effect in clusters of galaxies require excellent rejection of common-mode signals and wide frequency coverage. Aims. We describe an imaging, efficient, differential Fourier transform spectrometer (FTS), optimized for measurements of faint brightness gradients at millimeter wavelengths. Methods. Our instrument is based on a Martin-Puplett interferometer (MPI) configuration. We combined two MPIs working synchronously to use the whole input power. In our implementation the observed sky field is divided into two halves along the meridian, and each half-field corresponds to one of the two input ports of the MPI. In this way, each detector in the FTS focal planes measures the difference in brightness between two sky pixels, symmetrically located with respect to the meridian. Exploiting the high commonmode rejection of the MPI, we can measure low sky brightness gradients over a high isotropic background. Results. The instrument works in the range ∼1−20 cm −1 (30−600 GHz), has a maximum spectral resolution 1/(2 OPD) = 0.063 cm −1(1.9 GHz), and an unvignetted throughput of 2.3 cm 2 sr. It occupies a volume of 0.7 × 0.7 × 0.33 m 3 and has a weight of 70 kg. This design can be implemented as a cryogenic unit to be used in space, as well as a room-temperature unit working at the focus of suborbital and ground-based mm-wave telescopes. The first in-flight test of the instrument is with the OLIMPO experiment on a stratospheric balloon; a larger implementation is being prepared for the Sardinia radio telescope.

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On the emissivity of wire-grid polarizers for astronomical observations at mm-wavelengths

Cited by 7 publications

References 13 publications

Common-mode rejection in Martin–Puplett spectrometers for astronomical observations at millimeter wavelengths

Common-mode rejection in Martin–Puplett spectrometers for astronomical observations at millimeter wavelengths

Ultra high molecular weight polyethylene: Optical features at millimeter wavelengths

Efficient differential Fourier-transform spectrometer for precision Sunyaev-Zel’dovich effect measurements

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