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This paper discusses the development of a cryogenic grating spectrometer that has been used to evaluate the performance of a post-dispersed polarizing FTS over the range of 285-500 µm.

The performance of a prototype far-infrared post-dispersed polarizing FTS has been measured using a source module consisting of unresolved emission and absorption lines and the results are compared with theoretical simulations.

We describe the engineering development unit of a novel cryogenic scan mechanism suitable for post-dispersed polarizing FTS instruments. Compliance to the stringent SPICA mission requirements is demonstrated through analyses and results from proof-of- concept activities.

This paper describes the development and status of a cryogenic, far-infrared, post- dispersed, polarizing FTS (PDPFTS), a candidate instrument concept for the next generation of far- infrared astronomical space telescopes.

The continued improvement in the sensitivity of superconducting far-infrared bolometers necessitates improved designs of cryogenically cooled broadband spectrometers in order to fully exploit the potential of such detectors. While Fourier transform spectrometers (FTS) have an illustrious history in astronomical research, the sensitivity of state-of-the-art detectors is such that the multiplex disadvantage of FTS is prohibitive unless the spectral bandpass can be restricted to less than 1%. One method of achieving this goal, and the one that has been adopted for the SPICA SAFARI instrument, is to use a diffraction grating as the post-dispersing component. Unlike a typical FTS, in which a single detector simultaneously measures a broad spectral band, a post-dispersed detection system requires multiple detectors, each with their own unique spectral, spatial, and temporal responses. Moreover, the narrow spectral band viewed by each detector results in an interferogram having a large coherence length; the signal is heavily modulated, yet truncated. While simulations play a useful role in modeling instrumental performance, there is no substitute for data obtained from a real implementation of an instrument concept. In this paper we describe the development and current status of a cryogenic, far-infrared, postdispersed, polarizing FTS (PDPFTS): a demonstrator for the SPICA SAFARI instrument.

The high spectral resolution mode of the SpicA FAR-infrared Instrument (SAFARI) is enabled by inserting a Fourier Transform Spectrometer (FTS), based on a Martin-Puplett interferometer, into the signal path of the instrument. The cryogenic mechanism (FTSM) enables linear scans of two back-to-back rooftop mirrors sharing a common apex. ABB Inc. is under contract with the Canadian Space Agency to develop and test at 4 K an FTSM Engineering Demonstration Unit (EDU) for TRL-5 demonstration. The main SAFARI FTSM performance drivers are the stringent mechatronic demands (position stability of roof-top mirrors

Recent advances in far-infrared detector technology have led to increases in raw sensitivity of more than an order of magnitude over previous state-of-the-art detectors. With such sensitivity, photon noise becomes the dominant noise component, even when using cryogenically cooled optics, unless a method of restricting the spectral bandpass is employed. One method is to use a low-resolution diffraction grating spectrometer to post-disperse the signal from a high-resolution instrument, such as a Fourier transform spectrometer (FTS). This concept has been adopted for the SAFARI instrument on the SPICA mission. This paper discusses the development of a prototype cryogenic grating spectrometer that has been used to evaluate the concept of a post-dispersed polarizing FTS over the range from 285-500 μm.

The sensitivity of state-of-the-art superconducting far-infrared (FIR) detectors is such that wideband spectroscopic observations, particularly those employing Fourier transform spectrometers (FTS), will require techniques to reduce the spectral bandwidth of a detector to limit the photon noise from an astronomical source. The proposed SPICA SAFARI instrument employs grating spectrometers to post-disperse the light that has been modulated by a polarizing FTS onto a detector array, thereby reducing the photon noise on each detector. While the principles of this method are understood, to date an integrated system has not been realized in the laboratory. We present the development of a FIR post-dispersed polarizing FTS (PDPFTS) consisting of a warm FTS and a 4 K grating spectrometer as a first step to a fully cryogenic PDPFTS demonstrator. Realistic astronomical spectra are generated by combining line emission from a tunable THz photomixer source with continuum emission from a variable blackbody source.

The sensitivity of state-of-the-art superconducting far-infrared detectors used in conjunction with cryogenically cooled space telescopes and instrumentation is such that spectroscopic observations are generally limited by photon noise from the astronomical source or by galactic foreground or zodiacal emission within the field-of-view. Therefore, an instrument design that restricts the spectral bandpass viewed by the detector must be employed. One method of achieving background limited, high resolution spectroscopy is to combine a high resolution component such as a Fabry-Pérot interferometer (FPI) with a lower resolution, post-dispersing system, such as a grating spectrometer, the latter serving to restrict the spectral bandpass. The resonant wavelength of an FPI is most often tuned by changing the spacing or medium between the parallel reflecting plates of the etalon. In this paper, we present a novel design for an FPI in which the wavelength is tuned by scanning the angle of incidence on a high refractive index etalon. This concept simplifies the cryomechanical design, actuation, and metrology. The first results from the realized instrument are presented and compared with theory. The effects on the spectral response as a function of the incident angle have been simulated and shown to agree well with the observation.

We provide a detailed description of the Herschel-SPIRE Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF). The FF is an automated process designed to extract significant spectral features from SPIRE FTS data products. Optimising the number of features found in SPIRE-FTS spectra is challenging. The wide SPIRE-FTS frequency range (447-1568 GHz) leads to many molecular species and atomic fine structure lines falling within the observed bands. As the best spectral resolution of the SPIRE-FTS is ~1.2 GHz, there can be significant line blending, depending on the source type. In order to find, both efficiently and reliably, features in spectra associated with a wide range of sources, the FF iteratively searches for peaks over a number of signal-to-noise ratio (SNR) thresholds. For each threshold, newly identified features are rigorously checked before being added to the fitting model. At the end of each iteration, the FF simultaneously fits the continuum and features found, with the resulting residual spectrum used in the next iteration. The final FF products report the frequency of the features found and the associated SNRs. Line flux determination is not included as part of the FF products, as extracting reliable line flux from SPIRE-FTS data is a complex process that requires careful evaluation and analysis of the spectra on a case-by-case basis. The FF results are 100% complete for features with SNR greater than 10 and 50-70% complete at SNR of 5. The FF code and all FF products are publicly available via the Herschel Science Archive., Comment: 20 pages, 8 figures, 8 tables, final version accepted by MNRAS June 2020

The sensitivity of state-of-the-art superconducting far-infrared detectors is such that astronomical observations at these wavelengths are limited by photon noise from the astronomical source unless a method of restricting the spectral bandpass is employed. One such method is to use a high resolution Fabry-Perot interferometer (FPI) in conjunction with a lower resolution, post-dispersing system, such as a grating spectrometer. The resonant wavelength of an FPI is typically tuned by changing the spacing or medium between the parallel reflecting plates of the etalon. We previously reported on a novel design in which the wavelength is tuned by scanning the angle of incidence, which simplifies the cryo-mechanical design, actuation and metrology. Here we present first light results from the realized instrument.

Over half of the light incident on the Earth from the Universe falls within the Far-Infrared (FIR) region of the spectrum. Due to the deleterious effects of the Earth's atmosphere and instrument self-emission, astronomical measurements in the FIR require space-borne instrumentation operating at cryogenic temperatures. These instruments place stringent constraints on the mechanical and thermal properties of the support structures at low temperatures. With high stiffness, tensile strength, strength-to-mass ratio, and extremely low thermal conductivity, carbon fibre reinforced polymers (CFRPs) are an important material for aerospace and FIR astronomical applications, however, little is known about their properties at cryogenic temperatures. We have developed a test facility for exploring CFRP properties down to 4 K. We present results from our ongoing study in which we compare and contrast the performance of CFRP samples using different materials, and multiple layup configurations. Current results include an evaluation of a cryostat dedicated for materials testing and a custom cryogenic metrology system, and preliminary cryogenic thermal expansion measurements. The goal of this research is to explore the feasibility of making CFRP-based, lightweight, cryogenic astronomical instruments.

We present the design and performance of a cryogenic, angle-scanned Fabry-Perot interferometer for far infrared astronomical spectroscopy. Novel features of the design are discussed, and the spectral response of the instrument is modeled. Experimental methods being developed to validate the spectral response are presented.

Nature is such that observations at far-infrared wavelengths are optimal for exploring both the nearby and distant Universe. The minute amount of energy carried by far-infrared photons, however, requires extremely sensitive instrumentation for their detection. Moreover, the instrumentation itself must be cooled to

The SPICA mission will employ ultra-sensitive superconducting detectors. In this case the multiplex disadvantage of Fourier transform spectroscopy dictates the use of a post-dispersed, diffraction grating detection system. The challenges of reconstructing astronomical spectra will be reviewed.

The high resolution spectroscopic mode of the SPICA SAFARI instrument will be achieved using a Martin-Puplett interferometer. The key science and technology requirements of the spectrometer will be reviewed and the current instrumental concept presented.

The sensitivity of state-of-the-art superconducting far-infrared detectors is such that astronomical observations at these wavelengths are limited by photon noise from the astronomical source unless a method of restricting the spectral bandpass is employed. One such method is to use a high resolution Fabry-Pérot interferometer (FPI) in conjunction with a lower resolution, post dispersing system, such as a grating spectrometer. The resonant wavelength of an FPI is typically tuned by changing the spacing or medium between the parallel reflecting plates of the etalon. We present a novel design in which the wavelength is tuned by scanning the angle of incidence, which simplifies the cryo-mechanical design, actuation and metrology. The effects on the spectral response as a function of incident angle have been simulated and shown to be manageable.

Imaging applications at terahertz frequencies are, in general, limited to relatively low spatial resolution due to the effects of diffraction. By using a subwavelength aperture in the near-field, however, it is possible to achieve subwavelength resolution, although low transmission through the aperture limits the sensitivity of this approach. Plasmonic lenses in the form of bullseye structures, which consist of a circular subwavelength aperture surrounded by concentric periodic corrugations, have demonstrated enhanced transmission, thereby increasing the utility of near-field imaging configurations. In this paper, the design, fabrication, and experimental performance of plasmonic lenses optimized for 300 GHz are discussed. While nanofabrication techniques are required for optical applications, microfabrication techniques are sufficient for terahertz applications. The process flow for fabricating a double-sided bullseye structure using a precision micromilling technique is described. Transmission and beam profile measurements using a customized terahertz testbed are presented.

The principles and practice of astronomical imaging Fourier transform spectroscopy (FTS) at far-infrared wavelengths are described. The Mach-Zehnder interferometer design has been widely adopted for current and future imaging FTS instruments; we compare this design with two other common interferometer formats. Examples of three instruments based on the Mach-Zehnder design are presented. The techniques for retrieving astrophysical parameters from the measured spectra are discussed using calibration data obtained with the Herschel SPIRE instrument. The paper concludes with an example of imaging spectroscopy obtained with the SPIRE FTS instrument., 10 pages; 9 figures. Accepted for publication in the Canadian Journal of Physics. v2: minor typographical changes to match published version

The FP7 project, FISICA (Far Infrared Space Interferometer Critical Assessment), called for the investigation into the suitability of Carbon fiber Reinforced Plastic (CFRP) for a 2m primary mirror. In this paper, we focus on the major challenge for application, the development of a mirror design that would maintain its form at cryogenic temperatures. In order to limit self-emission the primary is to be cooled to 4K whilst not exceeding a form error of 275nm PV. We then describe the development of an FEA model that utilizes test data obtained from a cryogenic test undertaken at the University of Lethbridge on CFRP samples. To conclude, suggestions are made in order to advance this technology to be suitable for such an application in order to exploit the low density and superior specific properties of polymeric composites.

Future far-infrared space astronomy missions will feature cryogenically cooled telescopes that will enable over 100x increase in sensitive over previous missions. The effects of pointing errors on FTS observations in this environment are discussed.

A cryogenic FTS is being developed at the University of Lethbridge based on a commercial rotary arm system. Measurement of optical path difference is accomplished using a fiber-fed laser interferometer system internal to the cryostat.

Imaging applications at terahertz (THz) frequencies are limited to relatively low spatial resolution due to the effects of diffraction. A subwavelength aperture can be used to improve the resolution at the cost of low transmission. Plasmonic lenses in the form of bullseye structures, consisting of a single subwavelength circular aperture surrounded by concentric periodic corrugations, have shown enhanced transmission and beam confinement. In this paper, we discuss the design and performance of plasmonic lenses optimized for transmission at 325 GHz., 2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz), August 23-28,2015, Hong Kong, China

Cryogenic optical equipment will become a standard requirement for future far infrared observatories. Here we outline the design of a cryogenic test bed for optical metrology and discuss its role in regards to component testing of future space-borne instruments.

We present an update on the ongoing commissioning of FTS-2, the imaging Fourier transform spectrometer ancillary instrument for use with the SCUBA-2 camera at the James Clerk Maxwell Telescope.

The Japanese SPace Infrared telescope for Cosmology and Astrophysics (SPICA), a 3 m class telescope cooled to ~ 6 K, will provide extremely low thermal background far-infrared observations. An imaging Fourier transform spectrometer (SAFARI) is being developed to exploit the low background provided by SPICA. Evaluating the performance of the interferometer translation stage and key optical components requires a cryogenic test facility. In this paper we discuss the design challenges of a pulse tube cooled cryogenic test facility that is under development for this purpose. We present the design of the cryostat and preliminary results from component characterization and external optical metrology.

We describe recent progress in the development of a lab-based spatial/spectral double Fourier interferometer within the Astronomical Instrumentation Group (AIG) laboratories at the University of Lethbridge, Canada (UL). This testbed interferometer is used in the development of spatial/spectral interferometry observation, data processing, characterization, and analysis techniques in the Far-Infrared (FIR) region of the electromagnetic spectrum. Several interferometry technological development milestones on the FIR astrophysics roadmap are addressed by this ongoing research program of the UL AIG, all of which are needed as precursors to an eventual space-based FIR interferometry mission. This research program is supported by recent CRC, CFI, and NSERC grants.

The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments on board the European Space Agency's Herschel Space Observatory which ended its operational phase on 29 April 2013. The low to medium resolution spectroscopic capability of SPIRE is provided by an imaging Fourier transform spectrometer (iFTS) of the Mach-Zehnder configuration. With their high throughput, broad spectral coverage, and variable resolution, coupled with their well-defined instrumental line shape and intrinsic wavelength and intensity calibration, iFTS are becoming increasingly common in far-infrared space astronomy missions. The performance of the SPIRE imaging spectrometer will be reviewed and example results presented. The lessons learned from the measured performance of the spectrometer as they apply to future missions will be discussed.

We present the latest commissioning results and instrument performance for the SCUBA-2 imaging Fourier Transform Spectrometer (FTS-2) installed at the James Clerk Maxwell Telescope (JCMT). This ancillary instrument provides intermediate spectral resolution (R ~10 to 5000) across both the 450 and 850 μm atmospheric transmission windows with a FOV of ~5 arcmin 2 . The superconducting TES sensors and SQUID readout of SCUBA-2 present unique challenges for operation of an FTS; the sensitivity requirements demand high detector linearity and stability in addition to control of systematic atmospheric and optical spillover effects. We discuss the challenges encountered during commissioning and ongoing efforts to mitigate their effects.

CCAT1 is a submillimeter telescope currently under development that will be located at an altitude of 5600 meters in the Andes mountains of northern Chile. The atmospheric transmission at this site will allow CCAT to achieve high sensitivity over a wide field of view and a broad wavelength range to provide an unprecedented capability for deep, large area multicolor submillimeter surveys. In order to achieve high aperture efficiencies out to frequencies of ~ 1 THz, the 162 individual panels that form the 25 meter aperture of CCAT must be aligned to a tolerance of a few microns rms. The design of a wavefront sensor to achieve this goal is presented.

A major limitation in terahertz (THz) imaging applications is the relatively poor diffraction limited spatial resolution. A common approach to achieve subwavelength resolution is near-field imaging using a subwavelength aperture, but the low transmission efficiency through the aperture limits the sensitivity of this method. Bullseye structures, consisting of a single subwavelength circular aperture surrounded by concentric periodic corrugations, have been shown to enhance transmission through subwavelength apertures. At optical wavelengths, the fabrication of bullseye structures has been traditionally achieved by lithographic or chemical processes. Since the scale of plasmonic structures depends on the incident wavelength, precision micromilling techniques are well suited for THz applications. In this paper we describe a diamond micromilling process for the fabrication a plasmonic lenses operating at 325 GHz. Theoretical simulations are obtained using an FDTD solver and the performance of the lens is measured using a customized THz test bed., New Developments in THz, RF, Millimeter-Waves, and Sub-Millimeter Waves III, February 1 2014, San Fransisco, CA, Series: Proceedings of SPIE; no. Vol. 8985

The design and performance of a dual polarizing bolometer detector system for use with a polarizing Fourier transform spectrometer to conduct broadband astronomical spectroscopy at submillimeter wavelengths is presented. The system features a fully differential electronics design which virtually eliminates common mode noise. The optical design efficiently rejects unwanted radiation, both spectrally and spatially, while minimizing the effects of resonant optical cavities. The system is cooled by an efficient, closed cycle 4He–3He refrigerator which is cycled under computer control. The noise performance of the system is determined from analysis of electrical, optical, and spectral measurements, and the results are compared with a theoretical bolometer model.

The spectral imaging capabilities of the Herschel-SPIRE imaging Fourier Transform Spectrometer are discussed. The process of data reduction and results from sample observations are presented.

We present early results from the commissioning of FTS-2, the imaging Fourier transform spectrometer for use with SCUBA-2 at the James Clerk Maxwell Telescope.

We report on the design and fabrication of an 8 K superconducting transition edge sensor (TES) bolometer with active heater feedback, for applications at far-infrared wavelengths. The bolometer is made using standard micro-fabrication techniques. The expected NEP is better than 1 pW/√ Hz.

We report on the fabrication and characterization of a voltage-biased superconducting bolometer (VSB) in a cryogen-free 4 K cryostat for applications at far-infrared wavelengths. The VSB is made using standard microfabrication techniques. An optical NEP of 0.83 pW/√Hz has been measured with a T c ∼7.12 K.

The Herschel/SPIRE imaging Fourier transform spectrometer employs detector arrays at each output port. The effects of divergence within the spectrometer, known as obliquity effects, are discussed within the context of Herschel/SPIRE.

We present the installation and pre-commissioning status of FTS-2, the imaging Fourier transform spectrometer for use with SCUBA-2 at the James Clerk Maxwell Telescope, and discuss synergies with the HERSCHEL\SPIRE and SPICA\SAFARI instruments.

The SCUBA-2 imaging Fourier Transform Spectrometer (FTS-2) is a dual-band Mach-Zehnder imaging spectrometer, built for use with the SCUBA-2 camera on the James Clerk Maxwell Telescope (JCMT). FTS-2 will provide resolving powers of R ~ 10 to 5000 across the 450 and 850 μm bands, with a FOV up to 5 arcmin2. The instrument has been built and tested, with first light on the telescope planned for fall 2010. We present the alignment process, laboratory test results, and discuss the first science targets in the context of other similar space and ground-based instruments.

The non-linear behaviour of bolometric detectors can lead to significant radiometric errors in Fourier spectroscopy if left uncorrected. We discuss preliminary investigation of this effect and its correction.

FTS-2 is an imaging Fourier transform spectrometer (IFTS) being developed for use with SCUBA-2, the second generation, wide-field, submillimetre camera which will operate at the James Clerk Maxwell Telescope (JCMT). The FTS-2 interferometer uses a folded Mach-Zehnder configuration and will provide simultaneous broadband spectral imaging across both the 850 and 450 μm bands with variable resolution ranging from resolving powers of R ~10 to 5000. Details of the instrument design, optical modeling, data reduction pipeline and calibration plan which have changed since the project CDR are discussed, along with preliminary results of lab integration and testing.

An Imaging Fourier Transform Spectrometer (IFTS), named FTS-2, is being developed by the University of Lethbridge for use with the SCUBA-2 sub-millimeter bolometric camera on the James Clerk Maxwell Telescope (JCMT). The FTS-2 optical model was developed and optimized in Zemax by the Institut National d'Optique (INO) to maximize the FOV and efficiency over a range of spectral resolutions. The IFTS has been designed as a folded system including corner cubes in the interferometer moving mirror, and extended polynomial surfaces in the interferometer folding mirrors. The instrument design for FTS-2 is described elsewhere; here we present an analysis of the modeled performance of the IFTS in terms of achievable Field Of View (FOV), spot pattern and vignetting, at Zero Path Difference (ZPD) and for the 2 resolution modes. The predicted imaging performance is compared to that of the SCUBA-2 camera alone.

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 DC- coupled, monolithic TES filled arrays operating at 450 and 850 mum 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).

We present the preliminary design of FTS-2, an imaging Fourier transform spectrometer (IFTS) for use with SCUBA-2, the second generation, wide-field, submillimetre camera currently under development for the James Clerk Maxwell Telescope (JCMT). This system, which is planned for operation at the start of 2007, will provide simultaneous broadband spectral imaging across both the 850 and 450 μm bands with variable resolution ranging from resolving powers of R ~10 to 5000. The spectrometer uses a folded Mach-Zehnder configuration and novel intensity beam dividers. The mechanical and optical design of FTS-2 as of the Critical Design Review stage of the project are discussed, along with the interfaces with SCUBA-2 and the JCMT.

We present the use of undersampling with a narrow band FTS operating in the step-and-integrate mode. Spectra can be unambiguously retrieved from interferograms sampled at less than the DC band-limited Nyquist sampling interval.

Imaging Fourier transform spectrometers (IFTS) are becoming the preferred systems for remote sensing spectral imaging applications because of their ability to provide, simultaneously, both high spatial and spectral resolution images of a scene. IFTS can be operated in either step-and-integrate or rapid-scan modes, where it is common practice to sample interferograms at equal optical path difference intervals. The step-and-integrate mode requires a translation stage with fast and precise point-to-point motion and additional external trigger circuitry for the detector focal plane array (FPA), and produces uniformly position-sampled interferograms which can be analyzed using standard FFT routines. In the rapid-scan mode, the translation stage is continuously moving and interferograms are often acquired at the frame-rate of the FPA. Since all translation stages have associated velocity errors, the resulting interferograms are sampled at non-uniform intervals of optical path difference, which requires more sophisticated analysis. This paper discusses the processing pipeline which is being developed for the analysis of the non-uniform rapid-scan data produced by the Herschel/SPIRE IFTS.

We present the recent developments and current design and of an imaging Fourier transform spectrometer (IFTS) for use with SCUBA-2, the second generation, wide-field, submillimetre camera currently under development for the James Clerk Maxwell Telescope (JCMT). The spectrometer will offer variable resolution with resolving powers ranging from R ~10 to 5000. The IFTS uses a folded Mach-Zehnder configuration with novel intensity beam dividers and dual input ports for continuous atmospheric cancellation. This system, which is planned for operation in 2006, will provide simultaneous, broadband, intermediate spectral resolution imaging across both the 850 and 450 μm bands. The optics, observing modes, and projected telescope performance of the IFTS are discussed.

We present the conceptual design of an imaging Fourier transform spectrometer (IFTS) for use with SCUBA-2, the second generation, wide-field, submillimeter camera currently under development for the James Clerk Maxwell Telescope (JCMT). This system, which is planned for operation in 2006, will provide simultaneous, broadband, intermediate spectral resolution imaging across both the 850 and 450 µm bands. The spectrometer will offer variable resolution with resolving powers ranging from R ~10 to 5000. When operated at low resolution, the IFTS will provide continuum measurements, well suited to spectral index mapping of molecular clouds, as well as bright nearby galaxies. The IFTS uses a folded Mach-Zehnder configuration and novel intensity beamdividers. The preliminary design, projected telescope performance and scientific impact of the IFTS are discussed. The preliminary design, novel observing modes, projected telescope performance and scientific impact of the IFTS are discussed.

SPIE Astronomical Telescopes + Instrumentation, 2004, Glasgow, United Kingdom, Series: Proceedings of SPIE; no. 5489