Supercam is a 345 GHz, 64-pixel heterodyne imaging array for the Heinrich Hertz Submillimeter Telescope
(HHSMT). By integrating SIS mixer devices with Low Noise Ampliers (LNAs) in 8 - 1x8 pixel modules, the
size needed for the cryostat and the complexity of internal wiring is signicantly reduced. All subsystems
including the optics, cryostat, bias system, IF boxes, and spectrometer have been integrated for all 64 pixels. In
the spring of 2012, SuperCam was installed on the HHSMT for an engineering run where it underwent system
level tests and performed rst light observations. In the fall of 2012 SuperCam will begin a 500 square degree
survey of the Galactic Plane in 12CO J=3-2. This large-scale survey will help answer fundamental questions
about the formation, physical conditions, and energetics of molecular clouds within the Milky Way. The data
set will be available via the web to all interested researchers.
We present a terahertz source based on difference frequency generation within a laser cavity. Combining the high
intracavity intensities of a dual-color vertical external cavity surface emitting laser (VECSEL) with the high nonlinear
coefficient of a periodically poled lithium niobate crystal enables the generation of milliwatts of continuous wave
terahertz radiation. As the frequency spacing between the two simultaneously oscillating laser lines can be adjusted
freely, the entire range of the terahertz gap can be covered. We discuss different approaches for the wavelength control
of the dual-color laser sources as well as emission characteristics of the nonlinear crystal. Exemplarily, we chose the
frequencies 1.9 THz to characterize the source in term of the beam shape, the linewidth and power scalability. To
investigate the emitted THz spectrum, heterodyne detection is employed.
The size of existing and projected submillimeter heterodyne receiver arrays is rapidly increasing. As receiver arrays
grow ever larger, the local oscillator power they require increases as well. We have developed Terahertz (THz)
Traveling Wave Tube Amplifiers (TWTA) that promise to provide more than enough power in the 200 to 700 GHz
frequency range to pump the largest arrays being planned for submillimeter telescopes. This technology combines
revolutionary carbon nanotube cathodes and electron gun design with unique software modeling and micro-fabrication
capabilities. We review key enabling technologies that make this breakthrough possible, present the design, realization,
computer models and preliminary results of the THz TWT we have fabricated at 220 and 350 GHz
Precise astronomical polarization measurements generally require the use of polarization modulation. We have developed a new modulator, the Variable-delay Polarization Modulator (VPM) which uses two modified Martin- Puplett interferometers to induce a physical path length difference between polarization components. This highly durable and efficient device can easily be adapted to a wide range of wavelengths and temperatures, making it well suited for air- and space-borne facilities. This paper discusses the basic modulator design and a comparison to the half-wave plate, as well as details of VPM tests conducted at the Submillimeter Telescope Observatory (SMTO).
Feedhorns like those commonly used in radio-telescope and radio communication equipment couple very efficiently (>98%) to the fundamental Gaussian mode (TEM00). High order modes are not propagated through a single-mode hollow metallic waveguides. It follows that a back to back feedhorn design joined with a small length of single-mode waveguide can be used as a very high throughput spatial filter. Laser micro machining provides a mean of scaling successful waveguide and quasi-optical components to far and mid infrared wavelengths. A laser micro machining system optimized for THz and far IR applications has been in operation at Steward Observatory for several years and produced devices designed to operate at λ=60μm. A new laser micromachining system capable of producing mid-infrared devices will soon be operational. These proceedings review metallic hollow waveguide spatial filtering theory, feedhorn designs as well as laser chemical etching and the design of a new high-NA UV laser etcher capable of sub-micron resolution to fabricate spatial filters for use in the mid-infrared.
We report on a novel approach for implementing a dual Bracewell nulling interferometric beam combiner using miniature conductive waveguides contained in a single monolithic structure. We present modeling results for these devices at mid-infrared wavelengths. Potential applications for these devices in the Terrestrial Planet Finder mission are discussed.
We report on the progress in developing cryogenic delay lines and
integrated optics components. These are some of the critical components needed to enable far-IR direct-detection interferometers. To achieve background-limited performance in the 40 to 400 μm region, th einterferometer optics and delay lines must be cooeld to near liquid Helium temperatures. Our cryogenic delay line designs incorporate a number of novel features and has been operated at liquid nitrogen temperatures. Our integrated optics effort has focued on producing single-mode spatial filters and beam combiners.
Laser induced, micro-chemical etching is a promising new technology that can be used to fabricate three dimensional structures many millimeters across with micrometer accuracy. Laser micromachining possesses a significant edge over more conventional techniques. It does not require the use of masks and is not confined to crystal planes. A non-contact process, it eliminates tool wear and vibration problems associated with classical milling machines. At the University of Arizona we have constructed the first such laser micromaching system optimized for the fabrication of THz and far IR waveguide and quasi-optical components. Our system can machine many millimeters across down to a few microns accuracy in a short time, with a remarkable surface finish. This paper presents the design, operation and performance of our system, and its applications to waveguide devices for sub millimeter and far IR interferometry.
The advent of large format (~100 pixel) spectroscopic imaging cameras at submillimeter wavelengths would fundamentally change the way in which astronomy is performed in this important wavelength regime. While the possibility of such instruments has been discussed for more than two decades, only recently have advances in mixer technology, device fabrication, micromachining, digital signal processing, and telescope design made the construction of such an instrument possible and economical. In our paper, we will present the design concept for a
10×10 heterodyne camera.
Laser induced micro chemical etching of silicon can be used to quickly and cheaply machine high-quality three-dimensional structures that would otherwise be nearly impossible to fabricate, in particular THz waveguide structures and quasi-optical components. At the University of Arizona, the construction and characterization of the first laser micro-machining system designed for waveguide components fabrication has been completed. Our system can be used to fabricate focal plane heterodyne mixer arrays, coherent beam combiners, AR grooved silicon lenses, phase gratings, single mode filters and more. Laser micro machining enables the fabrication of three-dimensional structures down to a few microns accuracy and up to 6 inches across in a short time. This presentation discusses the design and performance of our micro-machining system, and illustrates the type, range and performance of quasi- optical components this exciting new technology will make accessible.
Laser micromachining is a powerful alternative to the conventional fabrication of waveguide structures, feedhorns and backshorts designed to operate at frequencies greater than 800 GHz. Computer controlled laser etching permits the direct scaling and fabrication of successful waveguide designs to THz frequencies with micrometer tolerances in just a few hours. Laser micromachining can also be used to produce quasi optical components such as anti-reflection (AR) grooved silicon lenses, and local oscillator (LO) phase gratings. In these proceedings we describe the specifics of the laser micromachining facility being completed at the Steward Observatory Radio Astronomy Laboratory and its potential for the fabrication of THz imaging array receivers.
The Large Binocular Telescope (LBT) will consist of two, 8.417 m, spin-cast, optical quality primary mirrors on a common azimuth-elevation mount. The center-to-center distance between the primaries is 14.417 m. The LBT is being constructed on a site known to have relatively low atmospheric opacity at submillimeter wavelengths. In this paper we describe a unique 350 micrometer heterodyne receiver system designed for use on the LBT. The optical quality of the primaries and their size will give the LBT a light gathering power more than twice that of existing submillimeter-wave telescopes.
In this paper, we present the design for a 16-channel heterodyne array receiver for use on SOFIA. The array will be capable of using either hot-electron bolometers or membrane mounted Schottky diodes in efficient, low-cost waveguide mounts. Focal plane arrays will be constructed to target astrophysically important lines between approximately 1.9 and 3 THz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the FIR portion of the spectrum. An array receiver designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galaxy evolution in the present as well as past epochs. The proposed system uses the most sensitive detectors available in an efficient optical system.
Adonis, the Adaptive Optics instrument on use on the ESO 3.6m telescope in la Silla, is available for the astronomical community since April 1993. Since August 1996, a Posix-compatible toolset has been installed to perform the basic steps of infra-red data preprocessing in all imaging modes, and since May 1997, the Fabry-Perot observation mode is also handled. The principles and tools of pipeline processing for adaptive optics infrared data are introduced here, together with examples for Fabry-Perot imaging reduction.