Preliminary design of FTS-2: an imaging Fourier transform spectrometer for SCUBA-2

Naylor, David; Gom, Brad; Zhang, Baoshe

doi:10.1117/12.670552

Cited by 8 publications

(6 citation statements)

References 11 publications

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“…Fourier transform spectrometers (FTS) have been successfully used, both on ground-based telescopes and space observatories: SPIRE on Herschel (Griffin et al 2010), FIS-FTS on AKARI (Kawada et al 2008), PFS on Mars Express (Formisano et al 2005) and CIRS on the Cassini orbiter (Kunde et al 1996), BEAR at CFHT (Maillard & Michel 1982), FTS-2 at the James Clerk Maxwell Telescope (Naylor et al 2006), all working at infrared and submm wavelengths. Our team has also developped SpIOMM, SITELLE's prototype, at the Observatoire du Mont Mégantic (Grandmont 2003;Bernier 2006).…”

Section: Introductionmentioning

confidence: 99%

Optimal fitting of Gaussian-apodized or under-resolved emission lines in Fourier transform spectra providing new insights on the velocity structure of NGC 6720

Martin¹,

Prunet²,

Drissen³

2016

Mon. Not. R. Astron. Soc.

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An analysis of the kinematics of NGC 6720 is performed on the commissioning data obtained with SITELLE, the Canada-France-Hawaii Telescope's new imaging Fourier transform spectrometer. In order to measure carefully the small broadening effect of a shell expansion on an unresolved emission line, we have determined a computationally robust implementation of the convolution of a Gaussian with a sinc instrumental line shape which avoids arithmetic overflows. This model can be used to measure line broadening of typically a few km s −1 even at low spectral resolution (R less than 5000). We have also designed the corresponding set of Gaussian apodizing functions that are now used by ORBS, the SITELLE's reduction pipeline. We have implemented this model in ORCS, a fitting engine for SITELLE's data, and used it to derive the [S ii] density map of the central part of the nebula. The study of the broadening of the [N ii] lines shows that the Main Ring and the Central Lobe are two different shells with different expansion velocities. We have also derived deep and spatially resolved velocity maps of the Halo in [N ii] and Hα and found that the brightest bubbles are originating from two bipolar structures with a velocity difference of more than 35 km s −1 lying at the poles of a possibly unique Halo shell expanding at a velocity of more than 15 km s −1 .tionally robust implementation for small broadening values which avoids arithmetic overflows. In Section 3, we provide the definition of a set of Gaussian apodizing functions with an adjustable broadening parameter that is perfectly suitable for this model. We then apply this new line model to a data cube of the planetary nebula NGC 6720 (the Ring nebula, M 57), which was SITELLE's first target during commissioning. This analysis provides new insights on its velocity structure which are then presented in section 4.

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Section: Introductionmentioning

confidence: 99%

Optimal fitting of Gaussian-apodized or under-resolved emission lines in Fourier transform spectra providing new insights on the velocity structure of NGC 6720

Martin¹,

Prunet²,

Drissen³

2016

Mon. Not. R. Astron. Soc.

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“…If the dimensions of nearby channels in the spectrometer differ by less than the mechanical tolerance to which they are fabricated, then those channels cannot be resolved. This means that the maximum practical resolution of our half-wave resonator channels is approximately (9) At ASU, and at other high-precision machine shops, we have a precision milling machine that regularly achieves a 1 micron tolerance, which means that as shown in Fig. 8, a device should not be limited by machining tolerance below about 700 GHz.…”

Section: A Loss and Machining Tolerancesmentioning

confidence: 99%

“…Several groups are working on developing superconducting on-chip spectrometers (e.g., Super- Spec [4], [5], Micro-Spec [6], DESHIMA [7], and CAMELS [8]) based on either filter banks or on-chip gratings. Existing mm-wave spectrometers in the field include imaging Fourier transform spectrometers [9] and the Z-Spec waveguide gratingtype spectrometer [10]. Here, we present the design and prototype test results for a compact scalable waveguide filter-bank spectrometer.…”

Section: Introductionmentioning

confidence: 99%

A Compact Filter-Bank Waveguide Spectrometer for Millimeter Wavelengths

Bryan

Che

Groppi³

et al. 2015

IEEE Trans. THz Sci. Technol.

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We present the design and measurements of a 90GHz prototype of a millimeter-wave channelizing spectrometer realized in rectangular waveguide for astronomical instrumentation. The device was fabricated using conventional high-precision metal machining, and the spectrometer can be tiled into a 2D array to fill the focal plane of a telescope. Measurements of the fabricated five-channel device matched well with electromagnetic simulations using HFSS and a cascaded S-matrix approach. This motivated the design of a 54-channel R=200 spectrometer that fills the single-moded passband of rectangular waveguide in the 130-175 GHz and 190-250 GHz atmospheric windows for millimeter-wave spectroscopic mapping and multi-object spectroscopy.Comment: 7 pages, 8 figures, accepted by IEEE Transactions on Terahertz Science and Technolog

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“…spectral index mapping of molecular clouds), but will also provide useful information on bright nearby galaxies and planetary atmospheres. Previous papers have discussed the preliminary design [1] and observing modes [2] of FTS-2. In this paper we review the optical design and anticipated performance of the instrument as the project enters the final construction phase.…”

Section: Introductionmentioning

confidence: 99%

Optical design of the SCUBA-2 FTS

Naylor

Gom

Zhang

2007

2007 Joint 32nd International Conference on Infrared and Millimeter Waves and the 15th International Conference on Terahertz El

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FTS-2, an imaging Fourier Transform Spectrometer (IFTS) for use with the SCUBA-2 sub-millimetre bolometer array camera on the James Clerk Maxwell Telescope (JCMT), is currently under development by the University of Lethbridge and will be operational in 2008. SCUBA-2 features two DCcoupled, monolithic TES filled arrays operating at 450 and 850 μm with a total of ~10,000 bolometers. With its larger format and increased sensitivity, SCUBA-2 promises a factor of 1000 increase in mapping speed compared to its predecessors. When coupled with SCUBA-2, FTS-2 will fill a niche between the dual band SCUBA-2 continuum images and the higher spectral resolution, but smaller images produced by the JCMT heterodyne facility instrument HARP-B. The preliminary design of the FTS-2 system has been presented elsewhere; here we review the final optical design of the instrument as the project enters the construction phase. Since the FTS-2 project began after the SCUBA-2 feed optics design was already well underway, the optical design of FTS-2 was tightly constrained and presented unique challenges. In order to maximize the use of the available space, FTS-2 incorporates a folded Mach-Zehnder design including corner cubes in the moving mirror assembly and powered optics with polynomial surfaces in the interferometer arms. A retractable pickoff mirror system allows SCUBA-2 to be used with or without the spectrometer. Both input ports are placed on the sky for atmospheric cancellation, and both output ports are imaged on separate quadrants of the SCUBA-2 arrays. INO (Institut National d'Optique), with guidance from the University of Lethbridge, optimized the optical model for FTS-2 using Zemax to maximize the instrument Field Of View (FOV) and efficiency over the desired resolution range. We present an overview of the optical design, and the projected performance of the IFTS in terms of achievable FOV, spot pattern and vignetting, at Zero Path Difference (ZPD) and for the 2 resolution modes (~0.1 and 0.006 cm -1 ).

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Preliminary design of FTS-2: an imaging Fourier transform spectrometer for SCUBA-2

Cited by 8 publications

References 11 publications

Optimal fitting of Gaussian-apodized or under-resolved emission lines in Fourier transform spectra providing new insights on the velocity structure of NGC 6720

Optimal fitting of Gaussian-apodized or under-resolved emission lines in Fourier transform spectra providing new insights on the velocity structure of NGC 6720

A Compact Filter-Bank Waveguide Spectrometer for Millimeter Wavelengths

Optical design of the SCUBA-2 FTS

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