Engineering topics

Moseley, Samuel H.

Publications and source records attributed to Moseley, Samuel H..

At least 37 records · Page 2

NASA NTRS2012

Fabrication of a Silicon Backshort Assembly for Waveguide-Coupled Superconducting Detectors

The Cosmology Large Angular Scale Surveyor (CLASS) is a ground-based instrument that will measure the polarization of the cosmic microwave background to search for evidence for gravitational waves from a posited epoch of inflation early in the Universe s history. This measurement will require integration of superconducting transition-edge sensors with microwave waveguide inputs with excellent control of systematic errors, such as unwanted coupling to stray signals at frequencies outside of a precisely defined microwave band. To address these needs we present work on the fabrication of micromachined silicon, producing conductive quarter-wave backshort assemblies for the CLASS 40 GHz focal plane. Each 40 GHz backshort assembly consists of three degeneratively doped silicon wafers. Two spacer wafers are micromachined with through-wafer vias to provide a 2.04 mm long square waveguide delay section. The third wafer terminates the waveguide delay in a short. The three wafers are bonded at the wafer level by Au-Au thermal compression bonding then aligned and flip chip bonded to the CLASS detector at the chip level. The micromachining techniques used have been optimized to create high aspect ratio waveguides, silicon pillars, and relief trenches with the goal of providing improved out of band signal rejection. We will discuss the fabrication of integrated CLASS superconducting detector chips with the quarter-wave backshort assemblies.

Crowe, Erik J.↗

NASA NTRS2012

Fabrication of Silicon Backshorts with Improved Out-of-Band Rejection for Waveguide-Coupled Superconducting Detectors

The Cosmology Large Angular Scale Surveyor (CLASS) is a ground-based instrument that will measure the polarization of the cosmic microqave background to search for gravitational waves form a posited epoch of inflation early in the universe's history. This measurement will require integration of superconducting transition-edge sensors with microwave waveguide inputs with good conrol of systematic errors, such as unwanted coupling to stray signals at frequencies outside of a precisely defined microwave band. To address these needs we will present work on the fabrication of silicon quarter-wave backshorts for the CLASS 40GHz focal plane. The 40GHz backshort consists of three degeneratively doped silicon wafers. Two spacer wafers are micromachined with through wafer vins to provide a 2.0mm long square waveguide. The third wafer acts as the backshort cap. The three wafers are bonded at the wafer level by Au-Au thermal compression bonding then aligned and flip chip bonded to the CLASS detector at the chip level. The micromachining techniques used have been optimized to create high aspect ratio waveguides, silicon pillars, and relief trenches with the goal of providing improved out of band signal rejection. We will discuss the fabrication of integrated CLASS superconducting detectors with silicon quarter wave backshorts and present current measurement results.

Crowe, Erik J.↗

NASA NTRS2012

Performance and Calibration of H2RG Detectors and SIDECAR ASICs for the RATIR Camera

The Reionization And Transient Infra-Red (RATIR) camera has been built for rapid Gamma-Ray Burst (GRE) followup and will provide simultaneous optical and infrared photometric capabilities. The infrared portion of this camera incorporates two Teledyne HgCdTe HAWAII-2RG detectors, controlled by Teledyne's SIDECAR ASICs. While other ground-based systems have used the SIDECAR before, this system also utilizes Teledyne's JADE2 interface card and IDE development environment. Together, this setup comprises Teledyne's Development Kit, which is a bundled solution that can be efficiently integrated into future ground-based systems. In this presentation, we characterize the system's read noise, dark current, and conversion gain.

Fox, Ori D.↗

NASA NTRS2012

The GISMO-2 Bolometer Camera

We present the concept for the GISMO-2 bolometer camera) which we build for background-limited operation at the IRAM 30 m telescope on Pico Veleta, Spain. GISM0-2 will operate Simultaneously in the 1 mm and 2 mm atmospherical windows. The 1 mm channel uses a 32 x 40 TES-based Backshort Under Grid (BUG) bolometer array, the 2 mm channel operates with a 16 x 16 BUG array. The camera utilizes almost the entire full field of view provided by the telescope. The optical design of GISM0-2 was strongly influenced by our experience with the GISMO 2 mm bolometer camera which is successfully operating at the 30m telescope. GISMO is accessible to the astronomical community through the regular IRAM call for proposals.

Staguhn, Johannes G.↗

NASA NTRS2012

Exploring the Birth and Evolution of the Universe: How Detectors Have Revolutionized Space Astronomy

The past century has seen tremendous advances in the capability of instruments used for astronomical imaging and spectroscopy. Capabilities of instruments have expanded in many dimensions; the scale of telescopes has grown tremendously, the wavelengths used for astronomy have grown from visible light to the full electromagnetic spectrum, extending from gamma rays to low frequency radio waves. Additional advances have been enabled by the availability of space facilities, which eliminate the effects of the earths atmosphere and magnetosphere, and allow cooling of instruments to avoid instrumental thermal radiation. Even with all these advances, the increase in capability of detection systems has produced truly revolutionary improvements in capability. Today, I will describe the advances in astronomical detection from the photographic plates of the early 20th century to the giant high efficiency focal planes being developed for modern space and ground based astronomical instrument. I will review the demanding performance requirements set by space astronomy, and show how the detector community has risen to the challenge in producing high performance detectors for the Hubble Space Telescope, the Spitzer Space Telescope, and the James Webb Space Telescope, now under development.

Moseley, Samuel H.↗

NASA NTRS2011

The Impact of Standard Semiconductor Fabrication Processes on Polycrystalline Nb Thin Film Surfaces

Polycrystalline superconducting Nb thin films are extensively used for submillimeter and millimeter transmission line applications and, less commonly, used in microwave kinetic inductance detector (MKID) applications. The microwave and mm-wave loss in these films is impacted, in part, by the presence of surface nitrides and oxides. In this study, glancing incidence x-ray diffraction was used to identify the presence of niobium nitride and niobium monoxide surface layers on Nb thin films which had been exposed to chemicals used in standard photolithographic processing. A method of mitigating the presence of ordered niobium monoxide surface layers is presented. Furthermore, we discuss the possibility of using glancing incidence x-ray diffraction as a non-destructive diagnostic tool for evaluating the quality of Nb thin films used in MKIDs and transmission lines. For a given fabrication process, we have both the x-ray diffraction data of the surface chemistry and a measure of the mm-wave and microwave loss, the latter being made in superconducting resonators.

superconducting films↗

NASA NTRS2011

Image Registration for Stability Testing of MEMS

Image registration, or alignment of two or more images covering the same scenes or objects, is of great interest in many disciplines such as remote sensing, medical imaging. astronomy, and computer vision. In this paper, we introduce a new application of image registration algorithms. We demonstrate how through a wavelet based image registration algorithm, engineers can evaluate stability of Micro-Electro-Mechanical Systems (MEMS). In particular, we applied image registration algorithms to assess alignment stability of the MicroShutters Subsystem (MSS) of the Near Infrared Spectrograph (NIRSpec) instrument of the James Webb Space Telescope (JWST). This work introduces a new methodology for evaluating stability of MEMS devices to engineers as well as a new application of image registration algorithms to computer scientists.

Memarsadeghi, Nargess↗

NASA NTRS2010

Compact Magic-T using microstrip-slotline transitions

The design of a compact low-loss Magic-T is described. The planar Magic-T incorporates a compact microstrip-slotline tee junction and small microstrip-slotline transition area to reduce slotline radiation. The Magic-T produces broadband in-phase and out-of-phase power combiner/divider responses, has low in-band insertion loss, and small in-band phase and amplitude imbalance.

U-Yen, Kongpop↗

NASA NTRS2010

The EXIST Infra-Red Telescope System: Design and Performance

The Infra-Red Telescope is a critical element of the EXIST (Energetic X-Ray Imaging Survey Telescope) observatory. It is a passively cooled 1.lm visible/infrared telescope. The primary goal of the IRT is to obtain photometric and spectroscopic measurements of high redshift (>6) gamma ray burst afterglows to study the nature of these enigmatic events and their environments, and to use them as probes of the composition and ionization state of the intergalactic medium of the young universe. The IRT will provide a prompt follow up (within three minutes) of the transient discovered by the EXIST with exceptional NIR sensitivity (AB=24 in 100s) surpassing HST in the infrared due to its passively cooled (- 30 C) mirror. Its optical design and spectral coverage is tailored to the high redshift transient events that require prompt pointing, identification, accurate photometry and both low and high resolution spectroscopy. Here we describe the telescope, its instrument complement, and the cooling systems which provide its remarkable sensitivity

Moseley, Samuel H.↗

NASA NTRS2010

Microshutter Arrays for the JWST NIRSpec

A primary goal of the James Webb Space Telescope (JWST) is to characterize the birth and evolution of galaxies by imaging and spectroscopic observations. The telescope will use a Near Infrared Camera and a Near Infrared Spectrometer (NIRSpec) to carry out this program. The 3.6' x 3.6' field of NIRSpec will contain thousands of candidate high redshift galaxies. With such a high candidate object density, simultaneous multi-object capability is essential. This capability requires a programmable object selection mask to eliminate sky background and to reduce source confusion caused. We are developing a two-dimensional programmable field mask for NIRSpec. These masks employ micromechanical (MEMS) techniques to provide source selection over the NIRSpec field of view. The first flight format arrays (171x365 shutters) have been fabricated and full functionality of these arrays has been demonstrated in lab tests.

Moseley, Samuel H.↗

NASA NTRS2009

Interferometric polarization control

A signal conditioning module provides a polarimeter capability in a photometric system. The module may include multiple variable delay polarization modulators. Each modulator may include an input port, and a first arm formed to include a first reflector and first rooftop mirror arranged in opposed relationship. The first reflector may direct an input radiation signal to the first rooftop mirror. Each modulator also may include an output port and a second arm formed to include a second reflector and second rooftop mirror arranged in opposed relationship. The second reflector can guide a signal from the second rooftop mirror towards the output port to provide an output radiation signal. A beamsplitting grid may be placed between the first reflector and the first rooftop mirror, and also between the second reflector and the second rooftop mirror. A translation apparatus can provide adjustment relative to optical path length vis-a-vis the first arm, the second arm and the grid.

Wollack, Edward J.↗

NASA NTRS2009

Interferometric polarization control

Wollack, Edward J.↗

NASA NTRS2008

Superconducting Detectors Come of Age, or Ready to Leave the Lab

Cryogenically cooled superconducting detectors have become essential tools for a wide range of measurement applications, ranging from quantum limited heterodyne detection in the millimeter range to direct searches for dark matter with superconducting phonon detectors operating at 20 mK. Superconducting detectors have several fundamental and practical advantages which have resulted in their rapid adoption by experimenters. Their excellent performance arises in part from reductions in noise resulting from their low operating temperatures, but unique superconducting properties provide a wide range of mechanisms for detection. For example, the steep dependence of resistance with temperature on the superconductor normal transition provides a sensitive thermometer for calorimetric and bolometric applications. Parametric changes in the properties of superconducting resonators provide a mechanism for high sensitivity detection of submillil.neter photons. From a practical point of view, the use of superconducting detectors has grown rapidly because many of these devices couple well to SQUID amplifiers, which are easily integrated with the detectors. These SQUID-based amplifiers and multiplexers have matured with the detectors; they are convenient to use, and have excellent noise performance. The first generation of fully integrated large-scale superconducting detection systems is now being deployed. Improved understanding of the operation of these detectors, combined with rapidly improving fabrication techniques, is quickly expanding the capability of these detectors. I will review the development and application of superconductor-based detectors, the ultimate limits to their performance, and consider prospects for their future applications. Continued advances promise to enable important new measurements in physics, and with appropriate advances in cryogenic infrastn~cturem, ay result in the use of these detectors in everyday monitoring applications.

Moseley, Samuel H.↗

NASA NTRS2008

Interferometric Polarization Control

Chuss, David T.↗

NASA NTRS2008

High Resolution Near Infrared Spectrometer to Study the Zodiacal Light Spectrum

We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 612, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I line at 5184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program.

Kutyrev, Alexander↗

NASA NTRS2007

A Microshutter-Based Field Selector for JWST's Near Infared Spectrograph

One of the James Webb Space Telescope's (JWST) primary science goals is to characterize the epoch of galaxy formation in the universe and observe the first galaxies and clusters of galaxies. This goal requires multi-band imaging and spectroscopic data in the near infrared portion of the spectrum for large numbers of very faint galaxies. Because such objects are sparse on the sky at the JWST resolution, a multi-object spectrograph is necessary to efficiently carry out the required observations. We have developed a fully programmable microshutter array that will be used as the field selector for the Near Infrared Spectrograph (NIRSpec) on JWST. This device allows slits to be opened at the locations of selected galaxies in the field of view while blocking other unwanted light from the sky background and bright sources. In practice, greater than 100 objects within the field of view will be observed simultaneously. In this paper, we describe the microshutter arrays, their development, fabrication, testing, and progress toward delivery of flight qualified devices to the NIRSpec instrument team in 2008.

Silvergerg, Rorbert F.↗

NASA NTRS2007

A Compact Low-loss Magic-T using Microstrip-Slotline Transitions

The design of a compact low-loss magic-T is proposed. The planar magic-T incorporates the compact microstrip-slotline tee junction and small microstrip-slotline transition area to reduce slotline radiation. The experimental results show that the magic-T produces broadband in-phase and out-of-phase power combiner/divider responses, has an average in-band insertion loss of 0.3 dB and small in-band phase and amplitude imbalance of less than plus or minus 1.6 deg. and plus or minus 0.3 dB, respectively.

U-yen, Kongpop↗

NASA NTRS2006

Microshutter Arrays for the JWST NIRSpec

A primary goal of the James Webb Space Telescope (JWST) is to characterize the birth and evolution of galaxies by imaging and spectroscopic observations. The telescope will use a Near Infrared Camera and a Near Infrared Spectrometer (NIRSpec) to carry out this program. The 3.6 x 3.6 field of NIRSpec will contain thousands of candidate high redshift galaxies. With such a high candidate object density, simultaneous multi-object capability is essential. This capability requires a programmable object selection mask to eliminate sky background and to reduce source confusion caused. We are developing a two-dimensional programmable field mask for NIRSpec. These masks employ micromechanical (MEMS) techniques to provide source selection over the NIRSpec field of view. The first flight format arrays (171x365 shutters) have been fabricated and full functionality of these arrays has been demonstrated in lab tests. Qualification tests are in progress to demonstrate readiness for flight, and will be complete in the early fall of 2006. In this paper, I describe performance of this critical new technology, and progress in making the devices ready for a 2008 delivery to ESA for inclusion in the NIRSpec.

Moseley, Samuel H.↗