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1

Echelle gratings for the near-infrared  

NASA Astrophysics Data System (ADS)

We report on echelle gratings produced by diamond turning with groove spacings coarser than 20 lines per mm. Increasing the groove spacing of an echelle reduces the free spectral range allowing infrared orders to be matched to the detector size. Reflection echelle gratings designed for the near-infrared have potential wide application in both ambient temperature as well as cryogenic astronomical spectrographs. Diamond turned reflection echelle gratings are currently employed in space-based high-resolution spectrographs for 2 - 4 ?m planetary spectroscopy. Using a sample diamond turned grating we investigate the suitability of a 15 line/mm R3 echelle for use in ground-based 1 - 5 ?m spectroscopy. We find this grating suitable for 3 - 5 ?m high signal-to-noise, high-resolution applications. Controlling wavefront errors by an additional factor of two would permit use at high-resolution in the 1.5 - 2.5 ?m region.

Hinkle, Kenneth H.; Joyce, Richard R.; Bach, Bernhard W.; Bach, Erich; Bach, Kirk G.; Beam, Brooke M.; Poczulp, Gary; Smith, Verne V.; Wallace, Lloyd

2012-09-01

2

Design considerations for a large Airborne Infrared Echelle Spectrometer (AIRES)  

NASA Astrophysics Data System (ADS)

We propose a new facility instrument, the Airborne Infrared Echelle Spectrometer or 'AIRES'. The scientific rationale, a preliminary optical and mechanical design, and the instrument's estimated performance are presented. Some of the major technical challenges are discussed.

Haas, Michael R.; Erickson, Edwin F.; Colgan, Sean W. J.; Baltz, James A.; Lynch, Dana H.

3

Cryogenic infrared grating spectrometer.  

PubMed

A liquid-helium-cooled Ebert-Fastie grating spectrometer for use in a sounding rocket is described. Twelve detectors and associated filters separate the 5-70-microm spectral range into twelve intervals, each of which is scanned as the grating is rotated. The instrument was launched into an aurora from Fort Churchill, Canada, but a cryogenic failure occurred early in the flight, and only a small amount of data was obtained. PMID:20154781

McNutt, D P; Shivanandan, K; Daehler, M; Feldman, P D

1975-05-01

4

Cryogenic infrared grating spectrometer  

Microsoft Academic Search

A liquid-helium-cooled Ebert-Fastie grating spectrometer for use in a sounding rocket is described. Twelve detectors and associated filters separate the 5-70-micrometer spectral range into twelve intervals, each of which is scanned as the grating is rotated. The instrument was launched into an aurora from Fort Churchill, Canada, but a cryogenic failure occurred early in the flight, and only a small

D. P. McNutt; K. Shivanandan; M. Daehler; P. D. Feldman

1975-01-01

5

Cryogenic Grating Spectrometer.  

National Technical Information Service (NTIS)

The Cryogenic Grating Spectrometer (CGS) first flew on the KAO in 1982 December and has been open to guest investigators since 1984 October. In the past 12 years it has completed over 100 research flights supporting 13 different principal investigators st...

E. F. Erickson M. R. Haas S. W. J. Colgan J. P. Simpson R. H. Rubin

1995-01-01

6

First: Florida Ir Silicon Immersion Grating Spectrometer  

NASA Astrophysics Data System (ADS)

The FIRST silicon immersion grating spectrometer is being developed at UF to search for habitable Earth-like planets around M dwarfs and giant planets around young active stars. This compact cryogenic IR instrument is designed to have a spectral resolution of R=72,000 at 1.4-1.8 µm with a silicon immersion grating and R=60K at 0.8-1.35 µm with an R4 echelle. The goal is to reach a long term Doppler precision of 1-3 m/s for bright M dwarfs. The FIRST silicon immersion grating, with 54.74 degree blaze angle and 16 l/mm groove density, has been fully characterized in the lab. The 50x50 mm square grating entrance pupil is coated with a single layer of anti-reflection coating resulting in a 2.1% measured reflection loss. The grating surface was coated with a gold layer to increase grating surface reflectivity. It has produced R=110,000 diffraction limited spectral resolution at 1.523 micron in a lab test spectrograph with 20 mm pupil diameter. The integrated scattered light is less than 0.2\\% and grating has no visible ghosts down to the measuring instrument noise level. The grating efficiency is 69\\% at the peak of the blaze. This silicon immersion grating is ready for scientific observations with FIRST. FIRST is scheduled to be integrated in the lab during the spring of 2012 and see the first light at an astronomical telescope (TBD) the summer of 2012.

Ge, Jian; Zhao, B.; Wang, J.; Wan, X.; Powell, S.

2012-01-01

7

Exploiting a Transmission Grating Spectrometer.  

National Technical Information Service (NTIS)

The availability of compact transmission grating spectrometers now allows an attractive and economical alternative to the more familiar Czerny-Turner configuration for many high-temperature plasma applications. Higher throughput is obtained with short foc...

R. E. Bell

2004-01-01

8

AIRES: An Airborne Infra-Red Echelle Spectrometer for SOFIA  

NASA Astrophysics Data System (ADS)

SOFIA will enable astronomical observations with unprecedented angular resolution at infrared wavelengths obscured from the ground. To help open this new chapter in the exploration of the infrared universe, we are building AIRES, an Airborne Infra-Red Echelle Spectrometer. AIRES will be operated as a first generation, general purpose facility instrument by USRA, NASA's prime contractor for SOFIA. AIRES is a long slit spectrograph operating from 17 - 210 ?m. In high resolution mode the spectral resolving power is ~ 106 ?m/? or ~ 10 4 at 100 ?m. Unfortunately, since the conference, a low resolution mode with resolving power about 100 times lower has been deleted due to budgetary constraints. AIRES includes a slit viewing camera which operates in broad bands at 18 and 25 ?m.

Dotson, Jessie L.; Erickson, Edwin F.; Haas, Michael R.; Colgan, Sean W. J.; Simpson, Janet P.; Telesco, Charles M.; Piña, Robert K.; Wolf, Jürgen; Young, Erick T.

2000-03-01

9

Multilayer-coated echelle gratings for soft x rays and extreme ultraviolet  

Microsoft Academic Search

Mechanically ruled or ion-etched blazed diffraction gratings can be coated with multilayer reflectors to increase their on-blaze efficiency in the soft x-ray and extreme ultraviolet (EUV) spectral regions. The quality of the groove facets produced by these conventional manufacturing techniques precludes their use in high spectral orders to achieve high resolving power, i.e., as echelles. However, coarse gratings fabricated in

J. H. Underwood; C. Khan Malek; E. M. Gullikson; M. Krumrey

1995-01-01

10

AIRES: an airborne infrared echelle spectrometer for SOFIA  

NASA Astrophysics Data System (ADS)

The Stratospheric Observatory for Infrared Astronomy (SOFIA) will enable unique astronomical observations from visible to millimeter wavelengths. AIRES, a long-slit spectrograph with a mid-infrared slit viewing camera, would enable spectral imaging of gas-phase spectral features between 17 and 210 ?m with resolving powers from ~60,000 to 5000. The Cryogenic Grating Spectrometer (CGS: AIRES' predecessor) which was flown on NASA's Kuiper Airborne Observatory (KAO) for 13 years, demonstrated the importance of this wavelength range. A 1997 proposal to develop AIRES was selected as the highest-ranked of 19 U.S. competitors for first-generation SOFIA science instruments. Funding was terminated in 2001 due to budget problems associated with an original under estimate and the advent of full cost accounting in NASA. Here we summarize AIRES' expected performance, its science potential, its status, and lessons learned. Highlighted are three successfully accomplished major technical developments: the world's largest monolithic cryogenic grating, cryogenic multiplexing amplifiers for far-infrared germanium photoconductor detectors, and an optical/mechanical design in a package suitable for installation on SOFIA. We show that AIRES would fill a unique role among other spectroscopic capabilities foreseen for space-borne missions. AIRES' capabilities remain a high but unfilled priority for SOFIA, and for the science community in general.

Erickson, Edwin F.; Haas, Michael R.; Colgan, Sean J. W.; Dotson, Jessie L.; Simpson, Janet P.; Young, Erick T.

2007-10-01

11

Theory of a Concave Grating Spectrometer.  

National Technical Information Service (NTIS)

Apparatus constants for minimum defocussing of a concave grating spectrometer were determined. Equations were obtained relating apparatus constants, which were not obtainable in Seya theory. Numerical solutions were calculated by computer from an equation...

H. Greiner E. Schaeffer

1976-01-01

12

Performance Capabilities of Small Grating Spectrometers.  

National Technical Information Service (NTIS)

Some of the performance capabilities of grating infrared spectrometers, such as spectral resolving power, wave-number accuracy, analytical sensitivity and accuracy, and qualitative specificity, are demonstrated. Primary emphasis is given to resolving powe...

R. E. Kagarise

1966-01-01

13

An infrared grating spectrometer for GIRL  

Microsoft Academic Search

A grating spectrometer with medium spectral resolution was developed for the GIRL project (Experiment E3), for the determination of the emission of trace constituents in the Earth's atmosphere, and for planetary and astronomical measurements. The spectrometer consists of two Ebert-Fastie spectrometers covering the wavelength range between 2.5 and 100 micron. The engineering model of E3 is described, and the design

Peter Knieling; Guenther Lange; Dirk Offermann; Klaus-Ulrich Grossmann

1986-01-01

14

MISE: A multiwavelength imaging spectrograph using echelle grating for daytime optical aeronomy investigations  

NASA Astrophysics Data System (ADS)

A high-spectral resolution multiwavelength imaging slit spectrograph using echelle grating (MISE) that is capable of measuring daytime optical emissions at multiple wavelengths simultaneously over a large (140°) field-of-view is presented. Optical emissions during daytime (either dayglow or daytime aurora) are buried in the strong daytime solar scattered background continuum and therefore very high spectral resolution measurements are required to obtain their contributions. MISE measures the emission intensities of OI 557.7nm, OI 630.0nm, and OI 777.4nm that originate in the upper atmosphere. The dispersion achieved by the spectrograph at these three spectral regions, respectively, is 0.004, 0.0049, and 0.0059nmpixel?1. By using an echelle grating as the dispersing element, multiple spectral regions of aeronomic interest are made to fall in the same diffraction angle range so that rotation of grating is avoided. This instrument is immune to ambient temperature fluctuations and vibrations and is suitable for long and continuous field operations. The spectral and intensity calibration of this instrument along with the data analysis methodology are discussed. Sample data of emission intensities from all the three wavelengths mentioned above for a couple of days obtained from Hyderabad (17°N, 80°E; 8.7°N Mag. Lat.) are presented which show a good similarity when compared with those of empirical and photochemical model results. The OI 557.7nm daytime emissions are measured sparsely from ground-based techniques and ground-based OI 777.4nm daytime emissions from ground are presented for the first time, to the best of our knowledge. The variability is highlighted and the potential of such measurements to derive information on vertical coupling of atmospheric regions and wave dynamics during daytime are discussed.

Pallamraju, Duggirala; Laskar, Fazlul I.; Singh, Ravindra P.; Baumgardner, Jeffrey; Chakrabarti, Supriya

2013-10-01

15

Determination of Barium in Seawater by a Standard Addition Method Adapted to the Direct Current Echelle Optical Emission Spectrometer.  

National Technical Information Service (NTIS)

A technique for determining trace concentrations of barium in seawater is described. Analyses are performed using an optical emission spectrometer/spectrograph equipped with an echelle monochromator and a dc argon plasma excitation source. Calibration is ...

D. C. Bankston

1980-01-01

16

Electro-optic Phase Grating Streak Spectrometer  

SciTech Connect

The electro-optic phase grating streak spectrometer (EOPGSS) generates a time-resolved spectra equivalent to that obtained with a conventional spectrometer/streak camera combination, but without using a streak camera (by far the more expensive and problematic component of the conventional system). The EOPGSS is based on a phase, rather than an amplitude grating. Further, this grating is fabricated of electro-optic material such as, for example, KD*P, by either etching grooves into an E-O slab, or by depositing lines of the E-O material onto an optical flat. An electric field normal to the grating alters the material’s index of refraction and thus affects a shift (in angle) of the output spectrum. Ramping the voltage streaks the spectrum correspondingly. The streak and dispersion directions are the same, so a second (static, conventional) grating disperses the spectrum in the orthogonal direction to prevent different wavelengths from “overwriting” each other. Because the streaking is done by the grating, the streaked output spectrum is recorded with a time-integrating device, such as a CCD. System model, typical design, and performance expectations will be presented.

Goldin, F. J.

2012-08-02

17

Seya'S Theory of the Concave Grating Spectrometer.  

National Technical Information Service (NTIS)

A survey was made of those spectrometers (monochromators) which use the concave grating employing single reflection, those which are suitable for wavelengths below 1000 A. A brief resume of Seya's theory is given. This theory provides the basis for the de...

H. Greiner E. Schaeffer

1976-01-01

18

Compact Catadioptric Imaging Spectrometer Utilizing Reflective Grating.  

National Technical Information Service (NTIS)

An imaging spectrometer apparatus comprising an entrance slit for directing light, a light means for receiving the light and directing the light, a grating that receives the light from the light means and defracts the light back onto the light means which...

S. A. Lerner

2003-01-01

19

A balloon-borne grating spectrometer.  

PubMed

A balloon-borne, 0.5-m, Czerny-Turner grating spectrometer has been designed and constructed at the University of Denver and has measured atmospheric transmittance in several spectral regions between 2 micro and 14 micro. These data have been obtained on a series of eleven balloon flights at three geographic locations over a period of thirty months. The solar pointing system, spectrometer optics, electronics and recording system are described. The preflight and flight performance of the spectrometer is discussed and sample data presented. PMID:20057726

Murcray, D G; Murcray, F H; Williams, W J

1967-02-01

20

An infrared grating spectrometer for GIRL  

NASA Astrophysics Data System (ADS)

A grating spectrometer with medium spectral resolution was developed for the GIRL project (Experiment E3), for the determination of the emission of trace constituents in the Earth's atmosphere, and for planetary and astronomical measurements. The spectrometer consists of two Ebert-Fastie spectrometers covering the wavelength range between 2.5 and 100 micron. The engineering model of E3 is described, and the design data are given. The engineering model was verified during operation in a cryostat at liquid helium temperatures. The spectral channels and respective IR filters were designed. Stray light suppression during limb scan measurements is explained. Absorption and emission spectra of atmospheric trace gases were measured.

Knieling, Peter; Lange, Guenther; Offermann, Dirk; Grossmann, Klaus-Ulrich

1986-08-01

21

Preliminary optical design of AIRES: an airborne infrared echelle spectrometer for SOFIA  

NASA Astrophysics Data System (ADS)

NASA's Stratospheric Observatory for IR Astronomy (SOFIA) will enable unprecedented IR acuity at wavelengths obscured from the ground. To help open this new chapter in the exploration of the IR universe, we are developing the Airborne IR Echelle Spectrometer (AIRES) as a facility science instrument. Full funding was awarded for a four year development in October, 1997. The instrument is scheduled to come on-line with the observatory in the Fall of 2001. It will be used to investigate a broad range of phenomena that occur in the interstellar medium. AIRES will use a 1200 mm long, 76 degree blaze angle echelle to combine high resolution spectroscopy with diffraction-limited imaging in the cross-dispersion direction. Its three 2D detector arrays will prove good sensitivity over a decade in wavelength. An additional array will be used as a slit viewer for (lambda) echelle prototyping, and cryostat layout are described.

Haas, Michael R.; Erickson, Edwin F.; Baltz, James A.; Colgan, Sean W.; Lynch, Dana H.; McGuire, James P.; Pina, Robert K.; Roellig, Thomas L.; Simpson, Janet P.; Telesco, Charles M.; Wolf, Juergen; Young, Erick T.

1998-08-01

22

Quantitative analysis of mercury in silver dental amalgam alloy using laser induced breakdown spectroscopy with a portable Echelle spectrometer  

Microsoft Academic Search

Nowadays it is commonly ascertained that, Laser- induced breakdown spectroscopy (LIBS) was investigated to evaluate the feasibility as a fast, accurate, non contact and simple technique used in both qualitative and quantitative elemental analysis of metals in various environments. The used portable Echelle spectrometer (Mechelle 7500 - Multichannel Instruments, Stockholm, Sweden) permit real simultaneous multi-elemental analysis in rang of 200-900

Walid Tawfik; Ali Saafan

23

A transmission grating spectrometer for plasma diagnostics  

NASA Astrophysics Data System (ADS)

Radiation temperature is an important parameter in characterizing the properties of hot plasmas. In most cases this temperature is time varying caused by the short lived and/or time dependent nature of the plasma. Thus, a measurement of the radiation flux as a function of time is quite valuable. To this end the authors have developed a spectrometer that can acquire spectra with a time resolution of less than 1 ns and covers the spectral energy range from approximately 60 to 1,000 eV. The spectrometer consists of an entrance slit placed relatively near the plasma, a thin gold film transmission grating with aperture, a micro channel plate (MCP) detector with a gold cathode placed at the dispersion plane and an electron lens to focus the electrons from the MCP onto a phosphor coated fiber optic plug. The phosphor (In:CdS) has a response time of (approximately) 500 ps. This detector system, including the fast phosphor is similar to one that has been previously described. The spectrometer is in a vacuum chamber that is turbo pumped to a base pressure of approximately 5 x 10(exp 7) torr. The light from the phosphor is coupled to two streak cameras through 100 m long fiber optic cables. The streak cameras with their CCD readouts provide the time resolution of the spectrum. The spectrometer has a built in alignment system that uses an alignment telescope and retractable prism.

Bartlett, Roger J.; Hockaday, Robert G.; Gallegos, Cenobio H.; Gonzales, Joseph M.; Mitton, Vance

24

Calibration and efficiency of the Einstein objective grating spectrometer.  

PubMed

The Einstein Observatory, a large satellite dedicated to x-ray astronomy, carried the first large x-ray telescope to be placed in orbit and an objective grating spectrometer with two sets of gratings. This paper lists prelaunch calibration results and describes the derivation of spectrometer efficiency and resolution. Several calibration spectra are shown, and theoretical grating parameters are derived from the calibration results. PMID:20389987

Seward, F D; Chlebowski, T; Delvaille, J P; Henry, J P; Kahn, S M; Speybroeck, L V; Dijkstra, J; Brinkman, A C; Heise, J; Mewe, R; Schrijver, J

1982-06-01

25

Blaze wavelength of convex blazed grating in an Offner spectrometer  

NASA Astrophysics Data System (ADS)

Compared with other forms of spectrometer, Offner spectrometer with a concentric structure is offering a lot of advantages, such as a compact structure, better imaging quality, lower distortion, and so on, convex grating on the second mirror is the key-component in it. The efficiency of an optical system plays an important role in application, but the low diffraction efficiency of Laminar grating or sinusoidal grating leads to a disadvantage for using, to solve this problem, blazed grating with much higher diffraction efficiency is a good answer. In application, blaze wavelength of the grating should be chosen in the spectral range with the lowest responsivity for the detector, so a proper blaze angle and theoretical prediction on affects by tolerance are important in designing the convex blazed grating in an Offner spectrometer. Based on the process of designing an Offner spectrometer, this paper deduced an expression for the angle of incidence in YZ-plane on convex grating in Offner spectrometer, then got the corresponding blaze angle, and analyzed affects on blaze wavelength brought by any kinds of tolerance, showed how to make the blaze wavelength work precisely for application, a practical example is also given.

Yang, Bo; Liu, Chenglin; Ding, Xuezhuan; Wang, Xin; Liu, Yinnian

2010-05-01

26

A New Large Echelle Spectrometer for Measuring Atomic Transition Probabilities of Fe-group Ions  

NASA Astrophysics Data System (ADS)

Accurate atomic transition probabilities for weak lines connected to the ground and low metastable levels of Fe-group ions are needed for elemental abundance studies on metal-poor stars. Metal-poor stars represent the oldest observable stellar generation and offer a direct probe into the early history of nucleosynthesis and the chemical evolution of the Galaxy. Unexplained trends in relative Fe-group abundances, such as [Co/Cr], as a function of metallicity, or [Fe/H], have been observed. These trends may result from a breakdown in the local thermodynamic equilibrium (LTE) approximation used in traditional photosphere models underlying elemental abundance determinations. The ground and low metastable levels of Fe-group ions contain most of the Fe-group material in a stellar photosphere, and thus second spectra lines with low E.P.s are essentially immune to non-LTE effects. To improve lab data on important Fe-group lines we have developed a novel instrument based on a 3 meter focal length vacuum echelle spectrograph combined with an aberration corrected cross dispersion system and a UV sensitive CCD array. This spectrometer is capable of recording both emission and absorption spectra with high resolving power, very broad wavelength coverage, and high signal-to-noise. It is also free from the multiplex noise of a FTS, making it ideally suited for measuring branching fractions of very weak lines. The combination of very accurate branching fractions with radiative lifetimes from time-resolved laser-induced fluorescence will yield accurate absolute transition probabilities of weak second spectra lines with low E.P.s for the Fe-group elements. Instrument design and preliminary results will be presented. Supported by NASA Grant NNX09AL13G.

Wood, Michael; Lawler, J. E.

2012-01-01

27

Comparison of a transmission grating spectrometer to a reflective grating spectrometer for standoff laser-induced breakdown spectroscopy measurements  

SciTech Connect

We evaluate a new transmission grating spectrometer for standoff laser-induced breakdown spectroscopy (LIBS) measurements. LIBS spectra collected from standoff distances are often weak, with smaller peaks blending into the background and noise. Scattered light inside the spectrometer can also contribute to poor signal-to-background and signal-to-noise ratios for smaller emission peaks. Further, collecting standoff spectra can be difficult because most spectrometers are designed for laboratory environments and not for measurements in the field. To address these issues, a custom-designed small, lightweight transmission grating spectrometer with no moving parts was built that is well suited for standoff LIBS field measurements. The performance of the spectrometer was quantified through 10 m standoff LIBS measurements collected from aluminum alloy samples and measurements from spectra of a Hg-Ar lamp. The measurements were compared to those collected using a Czerny-Turner reflective grating spectrometer that covered a similar spectral range and used the same ICCD camera. Measurements using the transmission grating spectrometer had a 363% improved signal-to-noise ratio when measured using the 669 nm aluminum emission peak.

Weisberg, Arel; Craparo, Joseph; De Saro, Robert; Pawluczyk, Romuald

2010-05-01

28

Source Scanning Type X-Ray Grating Spectrometer  

Microsoft Academic Search

A method is proposed for designing an x-ray spectrometer which can scan a limited wavelength region without movement of the concave grating or the electronic counter. Spectrometers widely used in the past have consisted of a fixed x-ray source and a movable counter. This method is to use a fixed counter and a scanning x-ray source to avoid undesirable movement

Masao Sawada; Kenjiro Tsutsumi

1969-01-01

29

The polar coordinate X-ray grating spectrometer  

Microsoft Academic Search

A new principle applicable to the Rowland circle mechanisms of X-ray spectrometers is formulated, and is based on the geometry of the circle considered in terms of its polar coordinates relative to the pole of the grating. It allows continuous adjustment of the Rowland radius scanned; it confers flexibility in operation, yet simplifies construction of the instrument. A soft X-ray

A. Franks; M. Stedman; R. F. Braybrook

1973-01-01

30

Fabrication update on critical-angle transmission gratings for soft x-ray grating spectrometers  

NASA Astrophysics Data System (ADS)

Diffraction grating-based, wavelength dispersive high-resolution soft x-ray spectroscopy of celestial sources promises to reveal crucial data for the study of the Warm-Hot Intergalactic Medium, the Interstellar Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, and other areas of interest to the astrophysics community. Our recently developed critical-angle transmission (CAT) gratings combine the advantages of the Chandra high and medium energy transmission gratings (low mass, high tolerance of misalignments and figure errors, polarization insensitivity) with those of blazed reflection gratings (high broad band diffraction efficiency, high resolution through use of higher diffraction orders) such as the ones on XMM-Newton. Extensive instrument and system configuration studies have shown that a CAT grating-based spectrometer is an outstanding instrument capable of delivering resolving power on the order of 5,000 and high effective area, even with a telescope point-spread function on the order of many arc-seconds. We have fabricated freestanding, ultra-high aspect-ratio CAT grating bars from silicon-on-insulator wafers using both wet and dry etch processes. The 200 nm-period grating bars are supported by an integrated Level 1 support mesh, and a coarser external Level 2 support mesh. The resulting grating membrane is mounted to a frame, resulting in a grating facet. Many such facets comprise a grating array that provides light-weight coverage of large-area telescope apertures. Here we present fabrication results on the integration of CAT gratings and the different high-throughput support mesh levels and on membrane-frame bonding. We also summarize recent x-ray data analysis of 3 and 6 micron deep wet-etched CAT grating prototypes.

Heilmann, Ralf K.; Bruccoleri, Alex; Mukherjee, Pran; Yam, Jonathan; Schattenburg, Mark L.

2011-09-01

31

Optical design and diffraction analysis for AIRES: an airborne infrared echelle spectometer  

NASA Astrophysics Data System (ADS)

The optical design is presented for a long-slit grating spectrometer known as AIRES (Airborne InfraRed Echelle Spectrometer). The instrument employs two gratings in series: a small order sorter and a large steeply blazed echelle. The optical path includes four pupil and four field stops, including two narrow slits. A detailed diffraction analysis is performed using GLAD by Applied Optics Research to evaluate critical trade-offs between optical throughput, spectral resolution, and system weight and volume. The effects of slit width, slit length, oversizing the second slit relative to the first, on- vs off-axis throughput, and clipping at the pupil stops and other optical elements are discussed.

Haas, Michael R.

2003-02-01

32

Fags - a Fast Astronomical Grating Spectrometer  

NASA Astrophysics Data System (ADS)

A fast astronomical spectrometer is described using commercially available photographic lenses and a CCD detector. The size and weight of the instrument have been kept to a minimum to allow it to be used on telescopes as small as 0.6 m.

Denby, B.; Dalglish, R.; Meadows, V.; Taylor, K. N. R.

33

ZEUS-2: a second generation submillimeter grating spectrometer for exploring distant galaxies  

NASA Astrophysics Data System (ADS)

ZEUS-2, the second generation (z)Redshift and Early Universe Spectrometer, like its predecessor is a moderate resolution (R~1000) long-slit, echelle grating spectrometer optimized for the detection of faint, broad lines from distant galaxies. It is designed for studying star-formation across cosmic time. ZEUS-2 employs three TES bolometer arrays (555 pixels total) to deliver simultaneous, multi-beam spectra in up to 4 submillimeter windows. The NIST Boulder-built arrays operate at ~100mK and are readout via SQUID multiplexers and the Multi-Channel Electronics from the University of British Columbia. The instrument is cooled via a pulse-tube cooler and two-stage ADR. Various filter configurations give ZEUS-2 access to 7 different telluric windows from 200 to 850 micron enabling the simultaneous mapping of lines from extended sources or the simultaneous detection of the 158 micron [CII] line and the [NII] 122 or 205 micron lines from z = 1-2 galaxies. ZEUS-2 is designed for use on the CSO, APEX and possibly JCMT.

Ferkinhoff, Carl; Nikola, Thomas; Parshley, Stephen C.; Stacey, Gordon J.; Irwin, Kent D.; Cho, Hsiao-Mei; Halpern, Mark

2010-07-01

34

CCD readout for the IXO off-plane grating spectrometer  

NASA Astrophysics Data System (ADS)

The International X-ray Observatory (IXO) project is the result of a merger between the NASA Con-X and ESA/Jaxa XEUS mission concepts. The IXO mission outline has an X-ray grating spectrometer operating in the 0.3-1 keV band. CCDs are the ideal detector for the readout of the grating spectrometer instrument and have been flown in similar functions on XMM and Chandra. Here we review the Off-Plane X-ray Grating Spectrometer concept for IXO and discuss the optimization of CCD technology for detection in the 0.2-2 keV X-ray band. We will discuss improvements to the existing technology previously flown, and the use of new technology such as electron multiplying CCDs which can provide enhanced signal to noise at these soft X-ray energies, together with radiation hardening measures and methods of reducing sensitivity to optical stray light. We will also end by discussing alternative CMOS-based technology which may be developed in future years to replace the CCD technology, offering benefits of higher system integration and radiation hardness.

Holland, Andrew D.; Murray, Neil; Tutt, James; McEntaffer, Randall; Pool, Peter; Endicott, James

2009-08-01

35

Design of a hybrid-integrated MEMS scanning grating spectrometer  

NASA Astrophysics Data System (ADS)

Optical MEMS (micro electro mechanical systems) have been used to reduce size, weight and costs of any kind of optical systems very successfully starting in the last decades. Scientists at Fraunhofer IPMS invented a resonant drive for 1-d and 2-d MEMS scanning mirror devices. Besides mirrors also scanning gratings have been realized. Now, rapidly growing new applications demand for enhanced functions and further miniaturization. This task cannot be solved by simply putting more functionality into the MEMS chip, for example grating and slit structures, but by three dimensional hybrid integration of the complete optical system into a stack of several functional substrates. Here we present the optical system design and realization strategy for a scanning grating spectrometer for the near infrared (NIR) range. First samples will be mounted from single components by a bonder tool (Finetech Fineplacer Femto) but the option of wafer assembly will be kept open for future developments. Extremely miniaturized NIR spectrometer could serve a wide variety of applications for handheld devices from food quality analysis to medical services or materials identification.

Pügner, Tino; Knobbe, Jens; Grüger, Heinrich; Schenk, Harald

2011-09-01

36

Chirped holographic grating used as the dispersive element in an optical spectrometer  

NASA Astrophysics Data System (ADS)

We have developed a new design of optical spectrometer based on the use of a chirped holographic grating inscribed on a flat substrate. This type of grating has a surface modulation with a spatially varying period. The ability of the chirped grating to focus a beam is exploited to reduce significantly the physical dimensions of the instrument. Wavelength selection is achieved by a pure translation of the chirped grating. The properties of the chirped grating spectrometer have been characterized with different lasers and arc lamps and compared with those of two commercial spectrometers. A performance parameter has been defined, enabling the various instruments to be compared.

Fortin, Gilles; McCarthy, Nathalie

2005-08-01

37

Transmission grating based imaging spectrometers in the XUV and VUV for various plasmas  

NASA Astrophysics Data System (ADS)

This report describes the design of imaging survey spectrometers in the XUV and the VUV ranges respectively. These survey spectrometers provide space resolved spectra using free standing transmission gratings and CCD based direct photon detection. The spectrometers were tested on a table top reflex discharge. Spectra shown in this report highlight the space and spectral resolving capabilities of the spectrometers.

Kumar, D.; Parman, M.; Stutman, D.; Finkenthal, M.

2013-10-01

38

A Soft X-ray Spectrometer using a Highly Dispersive Multilayer Grating  

Microsoft Academic Search

There is a need for higher resolution spectrometers as a tool for inelastic x-ray scattering. Currently, resolving power around R = 10,000 is advertised. Measured RIXS spectra are often limited by this instrumental resolution and higher resolution spectrometers using conventional gratings would be prohibitively large. We are engaged in a development program to build blazed multilayer grating structures for diffracting

Tony Warwick; Howard Padmore; Dmitriy Voronov; Valeriy Yashchuk

2010-01-01

39

Linear FBG interrogation with a wavelength-swept fiber laser and a volume phase grating spectrometer  

Microsoft Academic Search

We propose a novel FBG (fiber Bragg grating) sensor system that uses a tunable wavelength laser and a volume phase grating spectrometer. The effect of nonlinear wavelength scanning and uneven power profile of the fiber laser, which substantially degrades the measurement accuracy, is minimized by using a spectrometer demodulation. The constructed sensor system showed linear output according to the Bragg

Hyunjin Kim; Minho Song

2011-01-01

40

Design and fabrication of an active polynomial grating for soft-X-ray monochromators and spectrometers  

Microsoft Academic Search

An active polynomial grating has been designed for use in synchrotron radiation soft-X-ray monochromators and spectrometers. The grating can be dynamically adjusted to obtain the third-order-polynomial surface needed to eliminate the defocus and coma aberrations at any photon energy. Ray-tracing results confirm that a monochromator or spectrometer based on this active grating has nearly no aberration limit to the overall

S.-J. Chen; C. T. Chen; S. Y. Perng; C. K. Kuan; T. C. Tseng; D. J. Wang

2001-01-01

41

Soft X-Ray Grating Spectrometer for Secondary-Excitation Using Synchrotron Radiation  

Microsoft Academic Search

A concave grating spectrometer of a new mounting mode for fluorescence X-rays in the region of 25 Å-300 Å excited by synchrotron radiation source has been constructed. This spectrometer is discussed from the stand point of (1) a ray tracing method, and (2) calibration of wavelength. The X-ray spectra for several sulfide compounds were obtained with this grating spectrometer using

Kazuo Taniguchi

1984-01-01

42

A Soft X-ray Spectrometer using a Highly Dispersive Multilayer Grating  

NASA Astrophysics Data System (ADS)

There is a need for higher resolution spectrometers as a tool for inelastic x-ray scattering. Currently, resolving power around R = 10,000 is advertised. Measured RIXS spectra are often limited by this instrumental resolution and higher resolution spectrometers using conventional gratings would be prohibitively large. We are engaged in a development program to build blazed multilayer grating structures for diffracting soft x-rays in high order. This leads to spectrometers with dispersion much higher than is possible using metal coated-gratings. The higher dispersion then provides higher resolution and the multilayer gratings are capable of operating away from grazing incidence as required. A spectrometer design is presented with a total length 3.8 m and capable of 105 resolving power.

Warwick, Tony; Padmore, Howard; Voronov, Dmitriy; Yashchuk, Valeriy

2010-06-01

43

Development of a critical-angle transmission grating spectrometer for the International X-Ray Observatory  

NASA Astrophysics Data System (ADS)

We present a high-resolution soft x-ray grating spectrometer concept for the International X-Ray Observatory (IXO) that meets or exceeds the minimum requirements for effective area (> 1, 000 cm2 for E < 1 keV) and spectral resolution (E/?E > 3, 000). At the heart of the spectrometer is an array of recently developed highefficiency blazed transmission gratings, the so-called critical-angle transmission (CAT) gratings. They combine the advantages of traditional transmission gratings (very low mass, extremely relaxed alignment and flatness tolerances) with those of x-ray reflection gratings (high efficiency due to blazing in the direction of grazing-incidence reflection). In addition, a CAT grating spectrometer is well-suited for co-existence with energy-dispersive highenergy focal plane detectors, since most high-energy x rays are neither absorbed, nor diffracted, and contribute to the effective area at the telescope focus. Since our initial successful x-ray demonstrations of the CAT grating concept with large-period and lower aspect-ratio prototypes, we have now microfabricated 200 nm-period silicon CAT gratings comprised of grating bars with the required dimensions (6 micron tall, 40 nm wide, aspect ratio 150), optimized for the 0.3 to 1.0 keV energy band. Preliminary analysis of recent x-ray tests show blazing behavior up to 1.28 keV in accordance with predictions.

Heilmann, Ralf K.; Ahn, Minseung; Bautz, Marshall W.; Foster, Richard; Huenemoerder, David P.; Marshall, Herman L.; Mukherjee, Pran; Schattenburg, Mark L.; Schulz, Norbert S.; Smith, Matthew

2009-08-01

44

Off-plane grating spectrometer for the International X-ray Observatory  

NASA Astrophysics Data System (ADS)

A dispersive spectrometer onboard the International X-ray Observatory (IXO) provides a method for high throughput and high spectral resolution at X-ray energies below 1 keV. An off-plane reflection grating array maximizes these capabilities. We present here a mature mechanical design that places the grating array on the spacecraft avionics bus 13.5 m away from the focal plane. In addition, we present the technology development plan for advancing the Technology Readiness Level to 6 for the Off-Plane X-ray Grating Spectrometer.

McEntaffer, Randall L.; Murray, Neil J.; Holland, Andrew; Lillie, Charles; Casement, Suzanne; Dailey, Dean; Johnson, Tim; Cash, Webster C.; Oakley, Phillip H.; Schultz, Ted; Burrows, David N.

2009-08-01

45

Optical systems for recording of holographic diffraction gratings for high-resolution spectrometer  

NASA Astrophysics Data System (ADS)

High-resolution spectrometer was designed to resolve the fine structure of discharge emitted radiation near hydrogenous line 4648.8 A. The device consists of two concave diffraction gratings with 2700 grooves per mm and the radius of curvature 1000 mm. Optical mounting is calculated in such a way that the second grating compensates aberration of the first one for one wavelength. Using slight nonequidistancy of grooves we reduce aberrations in narrow region near this wavelength and achieved limit of resolution about 0.015 A for the spectral region of interest: 464.18- 465.15 nm. Diffraction gratings for this spectrometer have been produced mechanically in Sate Vavilov Optical Institute, St. Petersburg, Russia, by EA Yakovlev. Gratings show good spectral and energetic characteristics at previous laboratory tests and will be used in spectrometer, which is under mounting now. Area of these gratings is limited by mechanical way of production. The limit size is 50 by 50 mm. To detect weak signals it could be good to increase the are of gratings. To do it we try to calculate optical mounting of recording of these gratings holography. Since classical method of recording using homocentric beams which go to the grating blank from the same side of it does not provide aberration compensation conditions, we calculated recording mounting using recording in opposite directed beams.

Sokolova, Elena A.

1999-08-01

46

Passive Spectroscopy Bolometers, Grating- And X-Ray Imaging Crystal Spectrometers  

SciTech Connect

This tutorial gives a brief introduction into passive spectroscopy and describes the working principles of bolometers, a high-resolution grating spectrometer, and a novel X-ray imaging crystal spectrometer, which is of particular interest for profile measurements of the ion temperature and plasma rotation velocity on ITER and future burning plasma experiments.

Bitter, M; Hill, K W; Scott, S; Paul, S; Ince-Cushmann, A; Reinke, M; Rice, J; Beiersdorfer, P; Gu, M F; Lee, S G; Broennimann, C; Eikenberry, E F

2007-11-07

47

High resolution interrogation technique based on linear photodiode array spectrometer for fiber Bragg grating sensors  

Microsoft Academic Search

A linear photodiode array spectrometer based, high resolution interrogation technique for fiber Bragg grating sensors is demonstrated. Spline interpolation and Polynomial Approximation Algorithm (PAA) are applied to the data points acquired by the spectrometer to improve the original PAA based interrogation method. Thereby fewer pixels are required to achieve the same resolution as original. Theoretical analysis indicates that if the

Songwei Zhang; Yuliang Liu; Fang Li

2007-01-01

48

The high-resolution cross-dispersed echelle white-pupil spectrometer of the McDonald Observatory 2.7-m telescope  

NASA Astrophysics Data System (ADS)

A new high-resolution cross-dispersed echelle spectrometer has been installed at the coude focus of the McDonald Observatory 2.7-m telescope. Its primary goal was simultaneously to gather spectra over as much of the spectral range 3400 A to 1 micrometer as practical, at a resolution R identical with lambda/Delta lambda which approximately = 60,000 with signal-to-noise ratio of approximately 100 for stars down to magnitude 11, using 1-h exposures. In the instrument as built, two exposures are all that are needed to cover the full range. Featuring a white-pupil design, fused silica prism cross disperser, and folded Schmidt camera with a Tektronix 2048x2048 CCD used at either of two foci, it has been in regularly scheduled operation since 1992 April. Design details and performance are described.

Tull, Robert G.; MacQueen, Phillip J.; Sneden, Christopher; Lambert, David L.

1995-03-01

49

Off-plane x-ray grating spectrometer for the International X-ray Observatory  

NASA Astrophysics Data System (ADS)

A dispersive spectrometer onboard the International X-ray Observatory (IXO) provides a method for high throughput and high spectral resolution at X-ray energies below 1 keV. An off-plane reflection grating array maximizes these capabilities. We present here a mature mechanical design that places the grating array on the spacecraft avionics bus 13.5 m away from the focal plane.

McEntaffer, Randall L.; Murray, Neil J.; Holland, Andrew; Lillie, Chuck; Casement, Suzanne; Dailey, Dean; Johnson, Tim; Cash, Webster; Oakley, Phil

2009-05-01

50

Development of a novel spectrometer for tongue coating analyzer based on volume holography transmissive grating  

NASA Astrophysics Data System (ADS)

Tongue diagnosis (TD) is an important diagnostic methods in the traditional Chinese medicine (TCM). According to the viewpoint of TCM, the changes of the tongue coating (TC) can reflect the pathological state of the patient. And the nature or severity of diseasec can be determined by observing the TC. Over the years, TD is mostly depended on the subjective experience of the Chinese physician. And the diagnostic results will be impacted by.some factors, e.g. the different light sources or environmental brightness. Recently years, the method of digital image processing has been used into the TD. But its application is limited by the complicated algorithm, time-consuming and big error, etc. Therefore, a novel tongue coating analyzer(TCA) is designed in this paper. Meanwhile, a novel spectrometer for TCA based on the volume holography transmissive (VHT) grating is developed. In this spectrometer, since the VHT grating doesn't produce the stray-light due to the absence of the grooves of classical surface-embossed gratings, the VHT grating is used as the diffraction grating instead of the classical plane or concave grating. Experimental results show that the performances of the spectrometer for TCA have been improved by using the VHT grating, optimizing the light-path structure and software algorithm, etc. Compared with the others, this spectrometer for TCA has many advantages, such as, less diffraction, wider spectrum range, higher efficiency and resolution, etc. The spectrum range of the spectrometer for TCA can reach 300-1000nm, its resolution can reach 1nm and the optical density is larger than 3.

Ren, Zhong; Liu, Guodong; Dai, Longmin; Huang, Zhen; Zeng, Lvming

2010-11-01

51

A compact optical spectrometer based on a single-grating Fresnel diffractive optical element  

NASA Astrophysics Data System (ADS)

Recently, we have demonstrated a hybrid diffractive optical element that combines the dispersion function of a grating and the focusing function of a Fresnel lens (G-Fresnel) into a single device. The G-Fresnel promises a low f-number enabling miniaturization of a spectrometer system while maintaining high spectral resolution. A proof-of-concept G-Fresnel based spectrometer is demonstrated, yielding sub-nanometer resolution. Due to its compactness and low-cost fabrication technique, the G-Fresnel based spectrometer has the potential for use in mobile platforms such as lab-on-a-chip microfluidic devices and other mobile spectrometer applications.

Yang, Chuan; Edwards, Perry S.; Shi, Kebin; Liu, Zhiwen

2012-05-01

52

Calibration of a flat field soft x-ray grating spectrometer for laser produced plasmas  

Microsoft Academic Search

We have calibrated the x-ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL

G. V. Brown; M. B. Schneider; H. A. Baldis; P. Beiersdorfer; K. V. Cone; R. L. Kelley; C. A. Kilbourne; E. W. Magee; M. J. May; F. S. Porter

2010-01-01

53

Calibration of a helium-cooled infrared spatial radiometer and grating spectrometer  

Microsoft Academic Search

Methods used by the Space Dynamics Laboratory of Utah State University (SDL\\/USU) to calibrate infrared sensors are described, using the Infrared Background Signature Survey (IBSS) spatial radiometer and grating spectrometer as examples. A calibration equation and a radiometric model are given for each sensor to describe their responsivity in terms of individual radiometric parameters. The calibration equation terms include dark

Larry E. Jacobsen; Steve Sargent; Clair L. Wyatt; Allan J. Steed

1990-01-01

54

The Off-Plane X-ray Grating Spectrometer for the International X-ray Observatory  

NASA Astrophysics Data System (ADS)

The baseline configuration for the International X-ray Observatory (IXO) includes a soft x-ray grating spectrometer as part of its instrument complement to provide a spectral resolution of R >3000 over the 0.3 - 1 keV band with >1000 square cm effective collecting area. Using the current generation of reflection gratings flown on rocket experiments as a point of departure, an Off-Plane X-ray Grating Spectrometer (OP-XGS) is being proposed to the project to meet this need. These rocket experiments have demonstrated R of >100 with wire grid collimators and objective gratings that produce large point spread functions. Prototype gratings fabricated for the IXO project have achieved adequate throughput to obtain the IXO effective area requirement while resolution tests have demonstrated ?/?? > 200 when used with a 3 arc minute (angular resolution) telescope. When combined with the IXO telescope performance, the resulting spectral resolution is well over the IXO requirement. The OP-XGS will thus provide higher spectral resolution (over a slightly smaller energy range) than the Chandra LETGS instrument but with a larger effective collecting area providing improved sensitivity. The conceptual design and predicted performance of this system is presented here, along with the technology developments that will be needed to achieve the desired performance.

Casement, Suzanne; Johnson, T.; Lillie, C.; McEntaffer, R.; Cash, W.

2009-09-01

55

The Off-Plane X-ray Grating Spectrometer for the International X-ray Observatory  

NASA Astrophysics Data System (ADS)

The baseline configuration for the International X-ray Observatory (IXO) includes a soft x-ray grating spectrometer as part of its instrument complement to provide a spectral resolution of R >3000 over the 0.3 - 1 keV band with >1000 cm2 effective collecting area. An Off-Plane X-ray Grating Spectrometer (OP-XGS) is being proposed to the project to meet this need, using experience gained with the current generation of reflection gratings already flown on rocket experiments. These rocket experiments have demonstrated R of >100 with wire grid collimators and objective gratings that produce large point spread functions. Prototype gratings fabricated for the IXO project have achieved adequate throughput to obtain the IXO effective area requirement while resolution tests have demonstrated ?/?? > 200 when used with a 3 arc minute (angular resolution) telescope. When combined with the IXO telescope performance, the resulting spectral resolution is well over the IXO requirement. The conceptual design, two trade options, and predicted performance of this system is presented here, along with the technology developments that will be needed to achieve the desired performance.

Casement, L. Suzanne; Johnson, T. P.; Lillie, C.; McEntaffer, R.; Cash, W.

2010-01-01

56

High resolution hadamard transform spectrometer.  

PubMed

The ir spectrometer described employs alkaline halide lenses, an echelle grating, and a cryogenically cooled doped germanium bolometer as a detector. It is provided for two possible modes of operation: one is a single slit or conventional scan, the other is a multiplex or Hadamard scan. Signal strength, noise characteristics, scanning time, and available computer facilities determine the mode of operation. Sample spectra are presented. PMID:20111540

Hansen, P; Strong, J

1972-03-01

57

Compact grating spectrometer with an InSb array detector (Poster)  

NASA Astrophysics Data System (ADS)

A compact cooled grating spectrometer was built and has currently been put into use on several telescopes for near-infrared spectrophotometric observations. The spectrometer with the resolving power between 150 and 300 has been installed in an HD-3 dewar, utilizing an InSb array detector with eight elements. The detectivity when attached to a 2-m class telescope is characterized by 3 ? detection limits of about 1×10-20W cm-2 in the K-band and 6×10-20W cm-2 in the L-band by the typical integration time of 300 sec.

Suto, H.; Mizutani, K.; Maihara, T.; Nakajima, T.

58

Calibration of a high resolution grating soft x-ray spectrometer.  

PubMed

The calibration of the soft x-ray spectral response of a large radius of curvature, high resolution grating spectrometer (HRGS) with a back-illuminated charge-coupled device detector is reported. The instrument is cross-calibrated for the 10-50 A? waveband at the Lawrence Livermore National Laboratory electron beam ion trap (EBIT) x-ray source with the EBIT calorimeter spectrometer. The HRGS instrument is designed for laser-produced plasma experiments and is important for making high dynamic range measurements of line intensities, line shapes, and x-ray sources. PMID:21034013

Magee, E W; Dunn, J; Brown, G V; Cone, K V; Park, J; Porter, F S; Kilbourne, C A; Kelley, R L; Beiersdorfer, P

2010-10-01

59

A Near-Infrared Spectrometer Based on Novel Grating Light Modulators  

PubMed Central

A near-infrared spectrometer based on novel MOEMS grating light modulators is proposed. The spectrum detection method that combines a grating light modulator array with a single near-infrared detector has been applied. Firstly, optics theory has been used to analyze the essential principles of the proposed spectroscopic sensor. Secondly, the grating light modulators have been designed and fabricated by micro-machining technology. Finally, the principles of this spectroscopic sensor have been validated and its key parameters have been tested by experiments. The result shows that the spectral resolution is better than 10 nm, the wavelength deviation is less than 1 nm, the deviation of the intensity of peak wavelength is no more than 0.5%, the driving voltage of grating light modulators array device is below 25 V and the response frequency of it is about 5 kHz. With low cost, satisfactory precision, portability and other advantages, the spectrometer should find potential applications in food safety and quality monitoring, pharmaceutical identification and agriculture product quality classification.

Wei, Wei; Huang, Shanglian; Wang, Ning; Jin, Zhu; Zhang, Jie; Chen, Weimin

2009-01-01

60

Developments of the off-plane x-ray grating spectrometer for IXO  

Microsoft Academic Search

The International X-ray Observatory (IXO) is a collaborative effort between NASA, ESA, and JAXA. The IXO science goals are heavily based on obtaining high quality X-ray spectra. In order to achieve this goal the science payload will incorporate an array of gratings for high resolution, high throughput spectroscopy at the lowest X-ray energies, 0.3 - 1.0 keV. The spectrometer will

R. L. McEntaffer; N. J. Murray; A. D. Holland; J. Tutt; S. J. Barber; R. Harriss; T. Schultz; S. Casement; C. Lillie; D. Dailey; T. Johnson; R. Danner; W. Cash; B. Zeiger; A. Shipley; M. Page; D. Walton; P. Pool; J. Endicott; D. Willingale

2010-01-01

61

Science Simulations For The X-ray Grating Spectrometer Onboard The International X-ray Observatory  

Microsoft Academic Search

The International X-ray Observatory (IXO) is a collaborative effort between NASA, ESA, and JAXA. The IXO science goals are heavily based on obtaining high quality X-ray spectra. In order to achieve this goal the science payload will incorporate an array of gratings for high resolution, high throughput spectroscopy at the lowest X-ray energies, 0.3 - 1.0 keV. The spectrometer will

Randall L. McEntaffer; W. Cash; S. Casement; C. Lillie; A. Holland; N. Murray; M. Page

2010-01-01

62

Polychromator five-channel x-ray\\/EUV spectrometer with imaging transmission grating for plasma diagnostics  

Microsoft Academic Search

A new multichannel x-ray\\/extreme ultra violet (EUV) spectrometer is developed for monitoring the time history of x-ray\\/EUV spectral line intensities from a hot plasma to estimate an electron density and temperature of plasmas. Each independently controlled channel includes a crystal (or multilayer mirror) and a fast x-ray diode. At the same time, an imaging transmission grating is applied to study

Dmitry Fedin; Victor L. Kantsyrev; Bruno S. Bauer; Alla Shlyaptseva; Igor Brytov

1999-01-01

63

Impurity analysis of NSTX using a transmission grating-based imaging spectrometer  

NASA Astrophysics Data System (ADS)

A transmission grating-based imaging spectrometer has recently been installed and operated on the National Spherical Torus Experiment (NSTX) at PPPL. This paper describes the spectral and spatial characteristics of impurity emission under different operating conditions of the experiment—neutral beam heated, ohmic heated and RF heated plasma. A typical spectrum from each scenario is analyzed to provide quantitative estimates of impurity fractions in the plasma.

Kumar, Deepak; Finkenthal, Michael; Stutman, Dan; Bell, Ronald E.; Clayton, Daniel J.; Diallo, Ahmed; LeBlanc, Ben P.; Podesta, Mario; Tritz, Kevin

2012-06-01

64

Development of a Novel Breast Cancer Detector based on Improved Holography Concave Grating Imaging Spectrometer  

NASA Astrophysics Data System (ADS)

Breast cancer can be detected by B-mode ultrasonic imaging, X-mammography, CT imaging, and MRI. But some drawbacks existed in these methods, their applications was limited in some certain. So, a novel high resolution breast cancer detector (BCD) is developed in this paper. Meanwhile, an improved holography concave grating imaging spectrometer (HCGIS) is designed. In this HCGIS, the holography concave grating is used as the diffraction grating. Additionally, CCD with combined image acquisition (IAQ) card and the 3D scan platform are used as the spectral image acquisition component. This BCD consists of the light source unit, light-path unit, check cavity, splitting-light unit, spectrum acquisition and imaging unit, signal processing unit, computer and data analysis software unit, etc. Experimental results show that the spectral range of the novel BCD can reach 300-1000 nm, its wavelength resolution can reach 1nm, and this system uses the back-split-light technology and the splitting-light structure of holography concave grating. Compared with the other instruments of breast cancer detection, this BCD has many advantages, such as, compacter volume, simpler algorithm, faster processing speed, higher accuracy, cheaper cost and higher resolution, etc. Therefore, this BCD will have the potential values in the detection of breast disease.

Ren, Zhong; Liu, Guodong; Zeng, Lvming; Huang, Zhen

2011-01-01

65

Calibration of a flat field soft x-ray grating spectrometer for laser produced plasmas  

SciTech Connect

We have calibrated the x-ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL and at both the Omega and Omega EP lasers at the University of Rochester's Laboratory for Laser Energetics. The bandwidth of the VSG spans the range of {approx}6-60 A. The calibration results presented here include the VSG's dispersion and quantum efficiency. The dispersion is determined by measuring the x rays emitted from the hydrogenlike and heliumlike ions of carbon, nitrogen, oxygen, neon, and aluminum. The quantum efficiency is calibrated to an accuracy of 30% or better by normalizing the x-ray intensities recorded by the VSG to those simultaneously recorded by an x-ray microcalorimeter spectrometer.

Park, J.; Cone, K. V. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); University of California, Davis, One Shields Avenue, Davis, California 95616 (United States); Brown, G. V.; Schneider, M. B.; Beiersdorfer, P.; Magee, E. W.; May, M. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); Baldis, H. A. [University of California, Davis, One Shields Avenue, Davis, California 95616 (United States); Kelley, R. L.; Kilbourne, C. A.; Porter, F. S. [NASA Goddard Space Flight Center, Greenbelt, Maryland 20770 (United States)

2010-10-15

66

[Central wavelength shift analysis between laboratory and field spectral calibrations of grating based imaging spectrometer].  

PubMed

Spectral calibration must be carried out in order to determine its central wavelength and half-wave band width of each pixel before the usage of imaging spectrometer. But it was found out that these parameters vary as environment changes. The present paper studies the effect based on test field data. The authors analyzed the optical structure and compared the working environmental parameters. Then a theoretical model is established and the influences of vibration, distortion and temperature parameters are evaluated. The theoretical model and the caculation results are in good consistency, which testifies the theoretical model. This research will shed some light on the high accuracy spectral calibration of the grating based imaging spectrometer and its manufacture. PMID:24159894

Wang, Ming-Zhi; Yan, Lei; Yang, Bin; Gou, Zhi-Yang

2013-08-01

67

Production of high-order micromachined silicon echelles on optically flat substrates  

NASA Astrophysics Data System (ADS)

Infrared spectrometers using silicon immersion gratings and prisms can have substantial performance advantages over conventional instruments. The immersion gratings and grisms share a common geometry: prism-shaped pieces of silicon with blazed grooves along one side. The grooves can either be machined directly into substrates or the grooves can be machined into thin wafers which are then bonded to flat-surfaced prisms. Chemical micromachining currently is the best method of ruling grooves directly into silicon surfaces. The tolerances for near-IR diffraction gratings make direct machining of the grooves onto one surface of a bulky, prism-shaped substrate very difficult. We encountered a number of issues that we had to resolve when we tried to etch precisely positioned grooves into massive pieces of silicon: silicon substrate purity, lithography mask alignment, photoresist thickness uniformity, temperature control, wet etching vs. reactive-ion etching. We have successfully manufactured 7 line / mm gratings on 15 mm thick substrates. We performed optical tests with these gratings used as front-surface devices to determine efficiency and diffraction limited performance. Our echelle gratings have 70\\% efficiency in 365th-368th order at 632.8 nm. Testing shows that the grating preserves a diffraction-limited point-spread function making them good dispersing elements for applications requiring high spectral resolving power.

Ershov, Oleg A.; Jaffe, Daniel T.; Marsh, Jasmina P.; Keller, Luke D.

2001-11-01

68

A Tower Concept for the Off-Plane X-ray Grating Spectrometer for the International X-ray Observatory  

Microsoft Academic Search

An Off-Plane X-ray Grating Spectrometer (OP-XGS) concept is being developed to meet the needs of the International X-ray Observatory (IXO). The OP-XGS will provide the required spectral resolution of R >3000 over the 0.3 - 1 keV band with >1000 cm2 effective collecting area, using experience gained with the current generation of reflection gratings already flown on rocket experiments. We

L. Suzanne Casement; R. McEntaffer; W. Cash; T. Johnson; C. Lillie

2010-01-01

69

A tower concept for the off-plane x-ray grating spectrometer for the International X-ray Observatory  

Microsoft Academic Search

An Off-Plane X-ray Grating Spectrometer (OP-XGS) concept is being developed to meet the needs of the International X-ray Observatory (IXO). The OP-XGS will provide the required spectral resolution of R >3000 over the 0.3 - 1 keV band with >1000 cm2 effective collecting area, using experience gained with the current generation of reflection gratings already flown on rocket experiments. We

Suzanne Casement; Randall L. McEntaffer; Webster Cash; Tim Johnson; Charles Lillie; Dean Dailey

2010-01-01

70

Broadband FUV imaging spectrometer: advanced design with a single toroidal uniform-line-space grating  

NASA Astrophysics Data System (ADS)

Performances of a far-ultraviolet (FUV) imaging spectrometer in an advanced design are presented with a toroidal uniform-line-space (TULS) grating. It provides high spatial resolution and spectral resolution for a broadband and a wide field of view. A particular analysis for the grating aberrations, including all the high-order coefficients neglected by previous existing designs, was generated for indicating their significance. The analysis indicates that these high-order off-axis aberrations would have a remarkable influence on the design results. The transcendental equations composed of these aberration coefficients do not have analytic solutions in algebra. To solve the problem, the past designs always do some simplified calculation which only suits a narrow field of view and waveband. Thus, the optimization of the genetic algorithm is introduced to propose reasonable ranges of optical parameters. Then ZEMAX software is used to obtain the final optical system from these ranges. By comparing different design results of the same example, our advanced TULS design performs better than conventional TULS design and spherical varied-line-space grating design, and as well as the toroidal varied-line-space design. It is demonstrated that aberrations are minimized when the TULS design is operated by our method. The advanced design is low-cost, easy to fabricate, and more suitable for FUV observations.

Yu, Lei; Wang, Shu-Rong; Qu, Yi; Lin, Guan-Yu

2011-08-01

71

Electromagnetic versus scalar theory for modeling diffraction gratings: is electromagnetic modeling necessary for practical applications?  

Microsoft Academic Search

A critical analysis of grating behavior is presented over the entire spectrum, from millimeter waves to X rays. It concerns bare gratings used in resonance domain, VUV and XUV gratings used under near normal incidence, soft X-rays gratings used under grazing incidence, multilayer gratings and echelles for X rays, infrared and visible echelles, and transmission gratings. Polarization effects are pointed

Michel Neviere

1995-01-01

72

Design and simulation of arrayed waveguide grating (AWG) for micro-Raman spectrometer  

NASA Astrophysics Data System (ADS)

Micro Raman spectrometer has broad applications for monitoring harmful chemicals in food, water and environment. Arrayed waveguide grating (AWG) is a promising device to build a dispersive micro Raman spectrometer. Comparing with the widely used demultiplexer in optical communication, AWG in spectrometer is unique due to its broad spectral range and low insert loss. In this paper, a computer algorithm routine was explored to accomplish the design of a broadband, arbitrary AWG structure. First, the focal length, length increment of adjacent waveguide and diffraction order of an AWG were figured out by a MATLAB program, the coordinates was then input into a VBScript program to generate the layout, and the layout was analyzed in OptiwaveBPM software for optical characterization. The proposed MATLAB and VBScript program was verified by the design and simulation of a 800-1000 nm range, 40 channels asymmetric AWG, a spectral resolution of 5 nm was demonstrated with insert loss of 5.03-7.16 dB. In addition, an approach to realize multimode input was introduced to reduce the optical coupling loss. Multimode light beam was firstly converted to a series of single mode beams by the methods proposed by S. G. Leon-Saval et al. in 2005. Next, these single mode beams were coupled into the input star coupler of an AWG. As a proof of this concept, a three inputs, 20 channel, 850-950 nm spectral range AWG was simulated, and merits and drawbacks of this approach were discussed.

Cheng, Yaqin; Deng, Shengfeng; Xu, Yingchao; Lu, Miao

2012-10-01

73

High Resolution X-Ray Spectroscopy of zeta Puppis with the XMM-Newton Reflection Grating Spectrometer.  

National Technical Information Service (NTIS)

We present the first high resolution X-ray spectrum of the bright O4Ief supergiant star Puppis, obtained with the Reflection Grating Spectrometer on- board XMM-Newton. The spectrum exhibits bright emission lines of hydrogen-like and helium-like ions of ni...

S. M. Kahn M. A. Leutenegger J. Cottam G. Rauw J. M. Vreux A. J. F. denBoggende R. Mewe M. Guedel

2000-01-01

74

A soft x-ray transmission grating imaging-spectrometer for the National Ignition Facility  

SciTech Connect

A soft x-ray transmission grating spectrometer has been designed for use on high energy-density physics experiments at the National Ignition Facility (NIF); coupled to one of the NIF gated x-ray detectors (GXD) it records sixteen time-gated spectra between 250 and 1000eV with 100ps temporal resolution. The trade-off between spectral and spatial resolution leads to an optimized design for measurement of emission around the peak of a 100-300eV blackbody spectrum. Performance qualification results from the NIF, the Trident Laser Facility and VUV beamline at the National Synchrotron Light Source (NSLS), evidence a <100{micro}m spatial resolution in combination with a source-size limited spectral resolution that is <10eV at photon energies of 300eV.

Moore, A S; Guymer, T M; Kline, J L; Morton, J; Taccetti, M; Lanier, N E; Bentley, C; Workman, J; Peterson, B; Mussack, K; Cowan, J; Prasad, R; Richardson, M; Burns, S; Kalantar, D H; Benedetti, L R; Bell, P; Bradley, D; Hsing, W; Stevenson, M

2012-05-01

75

Multiwavelength campaign on Mrk 509. II. Analysis of high-quality Reflection Grating Spectrometer spectra  

NASA Astrophysics Data System (ADS)

Aims: We study the bright Seyfert 1 galaxy Mrk 509 with the Reflection Grating Spectrometers (RGS) of XMM-Newton, using for the first time the RGS multi-pointing mode of XMM-Newton to constrain the properties of the outflow in this object. We obtain very accurate spectral properties from a 600 ks spectrogram of Mrk 509 with excellent quality. Methods: We derive an accurate relative calibration for the effective area of the RGS and an accurate absolute wavelength calibration. We improve the method for adding time-dependent spectra and enhance the efficiency of the spectral fitting by two orders of magnitude. Results: Taking advantage of the spectral data quality when using the new RGS multi-pointing mode of XMM-Newton, we show that the two velocity troughs previously observed in UV spectra are resolved.

Kaastra, J. S.; de Vries, C. P.; Steenbrugge, K. C.; Detmers, R. G.; Ebrero, J.; Behar, E.; Bianchi, S.; Costantini, E.; Kriss, G. A.; Mehdipour, M.; Paltani, S.; Petrucci, P.-O.; Pinto, C.; Ponti, G.

2011-10-01

76

AEGIS: An Astrophysics Experiment for Grating and Imaging Spectroscopy---a Soft X-ray, High-resolution Spectrometer  

NASA Astrophysics Data System (ADS)

AEGIS is a concept for a high-resolution soft X-ray spectroscopic observatory developed in response to NASA's request for definitions of the next X-ray astronomy mission. At a small fraction of the cost of the once-planned International X-ray Observatory (IXO), AEGIS has capabilities that surpass IXO grating spectrometer requirements, and which are far superior to those of existing soft X-ray spectrometers. AEGIS incorporates innovative technology in X-ray optics, diffraction gratings and detectors. The mirror uses high area-to-mass ratio segmented glass architecture developed for IXO, but with smaller aperture and larger graze angles optimized for high-throughput grating spectroscopy with low mass and cost. The unique Critical Angle Transmission gratings combine low mass and relaxed figure and alignment tolerances of Chandra transmission gratings but with high diffraction efficiency and resolving power of blazed reflection gratings. With more than an order of magnitude better performance over Chandra and XMM grating spectrometers, AEGIS can obtain high quality spectra of bright AGN in a few hours rather than 10 days. Such high resolving power allows detailed kinematic studies of galactic outflows, hot gas in galactic haloes, and stellar accretion flows. Absorption line spectroscopy will be used to study large scale structure, cosmic feedback, and growth of black holes in thousands of sources to great distances. AEGIS will enable powerful multi-wavelength investigations, for example with Hubble/COS in the UV to characterize the intergalactic medium. AEGIS will be the first observatory with sufficient resolution below 1 keV to resolve thermally-broadened lines in hot ( 10 MK) plasmas. Here we describe key science investigations enable by Aegis, its scientific payload and mission plan. Acknowledgements: Support was provided in part by: NASA SAO contract SV3-73016 to MIT for the Chandra X-ray Center and Science Instruments; NASA grant NNX08AI62G; and the MKI Instrumentation Development Fund.

Huenemoerder, David; Bautz, M. W.; Davis, J. E.; Heilmann, R. K.; Houck, J. C.; Marshall, H. L.; Neilsen, J.; Nicastro, F.; Nowak, M. A.; Schattenburg, M. L.; Schulz, N. S.; Smith, R. K.; Wolk, S.; AEGIS Team

2012-01-01

77

Spectroscopic comparison between 1200 grooves/mm ruled and holographic gratings of a flat-field spectrometer and its absolute sensitivity calibration using bremsstrahlung continuum  

NASA Astrophysics Data System (ADS)

A flat-field extreme ultraviolet (EUV) spectrometer with a varied line spacing groove grating (1200 grooves/mm at grating center) has been developed to study the emission spectra from highly ionized medium Z impurities in large helical device (LHD). It covers a wavelength range of 50-500 A? using a mechanically ruled grating, which was later replaced by a newly developed laminar-type holographic grating for comparative studies. Differences in spectral resolution, intensities of higher order spectra, and sensitivities of the spectrometer were studied between the two gratings by observing the emission spectra of LHD plasmas. Although the achieved resolution was alike between them, i.e., ??~0.24 A? at 200 A?, the holographic grating was much superior in suppressing the higher order light than the ruled grating. The relative sensitivity between the two gratings was evaluated using continuum radiation from LHD plasmas. As a result, it was found that the holographic grating has a flat response in the full wavelength range, but the sensitivity of the ruled grating drops sharply below 200 A?. A new technique for the absolute calibration of the EUV holographic grating spectrometer was tried by combining the continuum radiation with a branching ratio of C IV lines (3p-3s: 5800 A?/3p-2s: 312 A?), and an accurate absolute sensitivity has been successfully obtained.

Chowdhuri, Malay Bikas; Morita, Shigeru; Goto, Motoshi; Nishimura, Hiroaki; Nagai, Keiji; Fujioka, Shinsuke

2007-02-01

78

The Upgraded Fiber Optic Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

The Upgraded Fiber Optic Echelle (UFOE) is a fiber-fed, white pupil echelle spectrograph to be implemented at the Hobby-Eberly Telescope (HET) in the spring of 1997. It will serve as the commissioning spectrograph until HET facility instruments come on line in early 1998. This instrument is a quick, cost effective upgrade of the Fiber Optic Echelle, resident at KPNO for a decade. The UFOE will be capable of R = 13,900 (Nyquist limited 2 pixels/resel), with complete spectral coverage from 530 nm to 850 nm and about 90% coverage to 900 nm with adequate order separation. It utilizes a 2.5 meter radius 400 mm diameter spherical mirror to reimage an ``average'' pupil between the echelle and the cross-dispersing grating onto the entrance pupil of a 200 mm f/2 camera lens. Due to the reduction of vignetting made possible with the pupil mirror, it is estimated that the UFOE will have an efficiency of 13% on the sky when used on the HET, whereas the FOE had an efficiency of 8%. This efficiency, combined with the 9 meter aperture of the HET, should allow a limiting magnitude of V = 18.9 for a 3000 second exposure with S/N = 30 per 1/2 resel. This spectrograph has been designed and constructed at Penn State and we present results of characterization of image quality, vignetting, and focal plane characteristics.

Harlow, J. J. B.; Ramsey, L. W.; Andersen, D. R.; Fleig, J. D.; Rhoads, B. T.; Engel, L. G.

1996-12-01

79

Design for an aberration-corrected concave grating for a mid-infrared long-slit spectrometer.  

PubMed

A new design for an aberration-corrected concave grating for the spectral region near 10 microm is presented. It was designed for use in the ground-based astronomical medium-resolution (lambda/Dlambda approximately 100) Mid-Infrared Camera and Spectrometer (MICS). It provides a flat focal plane for a wide spectral range (7.5-13.5 microm) with small aberrations, permitting efficient long-slit observations in the mid-infrared region. It permits a simple design of the spectrometer without collimator and camera mirrors, which is quite advantageous for cryogenic instruments. The grating has variable spacing grooves to reduce aberrations. In addition, the grating surface figure is designed to be toroidal and in the direction perpendicular to the grooves, aspherical, to suppress the aberrations further over a wide spectral range. The angle of the grooves is also varied to yield better efficiency near the blaze angle. The grating was fabricated by high-quality ultraprecision machining, which made these features possible. Test observations confirmed that the designed spectral resolution was achieved. PMID:18345038

Onaka, T; Miyata, T; Kataza, H; Okamoto, Y

2000-04-01

80

Grating spectrometer installation for electron cyclotron emission measurements on the DIII-D tokamak using circular waveguide and synchronous detection  

Microsoft Academic Search

The grating spectrometer installation on the DIII-D tokamak uses fundamental circular waveguide propagating the TE11 lowest-order mode followed by oversized circular guide carrying the low-loss TE01 mode. The short section of fundamental guide permits use of an electronic chopper operating at 100 kHz for both calibration and plasma operation. By using ac-coupled amplifiers tuned to the chopping frequency, the background

John Lohr; Gary Jahns; Charles Moeller; Ron Prater

1986-01-01

81

Off-plane x-ray grating spectrometer camera for IXO  

NASA Astrophysics Data System (ADS)

The International X-ray Observatory (IXO) is a merger of the former ESA XEUS and NASA Constellation-X missions, with additional collaboration from JAXA, proposed for launch ~2020. IXO will address the leading astrophysical questions in the 'hot universe' through its breakthrough capabilities in X-ray spectroscopy. The mission covers the 0.1 to 40 keV energy range, complementing the capabilities of the next generation observatories, such as ALMA, LSST, JWST and 30 meter ground-based telescopes. An X-ray Grating Spectrometer is baselined to provide science in the energy range 0.3-1.0 keV at a spectral resolution of E/?E > 3,000 with an effective area greater than 1,000 cm2. This will require an array of soft X-ray enhanced CCDs operating at a modest frame rate to measure the diffracted light in both position and energy. Here we describe the baseline camera for the Off-plane XGS instrument using mature CCD technology.

Murray, Neil J.; Holland, Andrew D.; Harriss, Richard D.; Tutt, James H.; Barber, Simeon J.; Pool, Peter; Endicott, James; Burt, David; Walton, Dave; Page, Mat; McEntaffer, Randall L.; Schultz, Ted; Cash, Webster C.; Lillie, Chuck; Casement, Suzanne

2010-07-01

82

Plane-grating flat-field soft x-ray spectrometer  

NASA Astrophysics Data System (ADS)

We describe a soft x-ray spectrometer covering the 120-800 eV range. It is intended for resonant inelastic x-ray scattering experiments performed at third generation synchrotron radiation (SR) facilities and has been developed with SOLEIL, the future French national SR source in mind. The Hettrick-Underwood principle is at the heart of the design using a combination of varied line-spacing plane grating and spherical-mirror to provide a flat-field image. It is slitless for optimum acceptance. This means the source size determines the resolving power. A spot size of <=5 ?m is planned at SOLEIL which, according to simulations, should ensure a resolving power >=1000 over the whole energy range. A 1024×1024 pixel charge-coupled device (CCD) with a 13 ?m×13 ?m pixel size is used. This is an improvement on the use of microchannel-plate detectors, both as concerns efficiency and spatial resolution. Additionally spectral line curvature is avoided by the use of a horizontal focusing mirror concentrating the beam in the nondispersing direction. It allows for readout using a binning mode to reduce the intrinsically large CCD readout noise. Preliminary results taken at beamlines at Elettra (Trieste) and at BESSY (Berlin) are presented.

Hague, C. F.; Underwood, J. H.; Avila, A.; Delaunay, R.; Ringuenet, H.; Marsi, M.; Sacchi, M.

2005-02-01

83

Improving the spectral resolution of soft x-ray flat-field spectrometer with multi-area gratings  

NASA Astrophysics Data System (ADS)

The ideal focal curve for the soft x-ray flat-field spectrometer is a straight line, but the real one is not, thus the inconformity of aberrations between different wavelengths in the working waveband is inevitable. In order to further reduce aberrations and improve spectral resolutions, multi-area gratings (divided perpendicular the direction of grating grooves) are devised. Firstly, the grating is divided into three areas, and the spectral aberrations for these areas are analyzed by means of ray tracing. Then, diffraction efficiencies for the areas with worse aberrations should be reduced to lower the proportion regional aberrations contributing to the overall aberration, therefore better spectral image could be obtained and the spectral resolution would be improved. Theoretical analysis demonstrates that: using multi-area grating, the spectral resolutions at wavelength of 0.8 and 1.1nm are increased from 123 and 333 to 401 and 671, respectively. At the same time, the spectral resolutions at other wavelengths are not reduced.

Chen, Huoyao; Liu, Zhengkun; Wang, Qingbo; Fu, Shaojun

2013-08-01

84

Design of a novel multi-spectral imaging spectrometer for breast cancer detector based on VHT grating  

NASA Astrophysics Data System (ADS)

The ultrasonic imaging, X-mammography, CT imaging and MRI can be applied into the breast cancer diagnosis(BCD). But some factors such as the spatial resolution, contrast and price-performance ratio (PPR) limit their applications. So, a novel BCD technology, that is, multi-spectral imaging is adopted into this paper. It can get more information of the breast tumor and higher identity because it combines the advantages of the spectroscopy and the imaging technology. And in this paper, the multi-spectral light source induced the breast cancer imaging detector(BCID) is designed, the spectrum can cover from the UV to NIR. Meanwhile, a custom-built multi-spectral imaging spectrometer (MSIS) is also developed. And, in order to overcome the stray-light of the light-route system and improve the resolution and light-passing efficiency of the system, the novel volume holography transmissive (VHT) grating instead of the plane or concave grating is used as the diffraction grating in this MSIS. Experimental result show that the novel BCD technology is feasible, it can offer not only the spectral information but also the image of the tumor. The spectrum resolution of the MSIS for BCID based on VHT grating can reach 2nm. Compared with the others, this BCID has more compact structure, faster speed, higher PPR and higher resolution and accuracy. Therefore, this BCID has the potential value in the field of the BCD.

Ren, Zhong; Wu, Yan; Liu, Guodong; Huang, Zhen; Zeng, Lvming

2011-06-01

85

Design and Operation of a Frequency Doubled Nd:YAG Thomson Scattering System with Transmission Grating ICCD Spectrometer  

NASA Astrophysics Data System (ADS)

A novel Thomson scattering system has been deployed on the Pegasus Toroidal Experiment. It provides a relatively low-cost, simplified design. Scattering is achieved using a 7 ns, 2 J frequency doubled Nd:YAG laser operating at 532 nm. The laser focuses to ˜3 mm diameter within the plasma via a 7 m beam-line. The beam-line contains cameras as beam finders and remotely adjustable mirrors for shot-to-shot alignment. A custom multi-element lens collects scattered photons from 15 cm < Rmaj< 85 cm with 1.2 cm radial resolution. Eight fiber optic bundles provide 8 spatial points for sampling the laser or background light. Each set of 8 channels is measured in a single spectrometer that utilizes a high efficiency (˜80%) volume phase holographic grating and a high quantum efficiency (> 40%) image intensified CCD (ICCD) camera. Three spectrometers provide a total of 24 channels. Two interchangeable gratings exist to cover low (Te = 10--100 eV) and high (Te = 0.10--1 keV) electron temperature regimes on Pegasus. The spectrometer is optimized for ne from mid-10^18 to mid-10^19 m-3. The signal-to-noise expected is ˜0.5 of an equivalent system using Nd:YAG at 1064 nm and avalanche photodiode detectors.

Schoenbeck, N. L.; Dowd, A. S.; Fonck, R. J.; Schlossberg, D. J.; Winz, G. R.

2012-10-01

86

Applications of Layered Synthetic Microstructures in Vacuum Ultraviolet and Soft X-Ray Grating Spectrometers.  

National Technical Information Service (NTIS)

Potential multilayer grating applications for the wavelength region from 6 to 350 A are discussed. Multilayer bandwidth and efficiency as affected by stack construction as well as the effects of roughness and corrections to Bragg's law are considered. Gra...

J. C. Rife

1988-01-01

87

Integrated x-ray testing of the electro-optical breadboard model for the X-ray Multimirror Mission (XMM) reflection grating spectrometer  

Microsoft Academic Search

X-ray calibration of the Electro-Optical Breadboard Model (EOBB) of the XMM Reflection Grating Spectrometer has been carried out at the Panter test facility in Germany. The EOBB prototype optics consisted of a four-shell grazing incidence mirror module followed by an array of eight reflection gratings. The dispersed x-rays were detected by an array of three CCDs. Line profile and efficiency

Jay V. Bixler; Henry J. Aarts; Wolfgang Burkert; Antonius J. den Boggende; G. Branduardi-Raymont; Heinrich W. Braeuninger; Albert C. Brinkman; William W. Craig; Todd A. Decker; Luc Dubbeldam; Christian Erd; Charles J. Hailey; Jan-Willem den Herder; Fred A. Jansen; Steven M. Kahn; Piet A. de Korte; C. W. Mauche; Frits B. Paerels; K. Thomsen

1994-01-01

88

The development of the Reflection Grating Spectrometer on board the XMM-Newton Observatory and its application to the study of accretion-powered sources  

NASA Astrophysics Data System (ADS)

The Reflection Grating Spectrometer on board the European Space Agency's XMM-Newton Observatory is the main subject of the thesis. It was designed to provide high-throughput, high-resolution spectroscopy in the soft X-ray band of 5 to 35 Å. The primary optical component is the Reflection Grating Array. The individual gratings were extensively calibrated at Columbia University's Nevis Laboratories. The grating array was assembled at Nevis and then calibrated as part of the integrated spectrometer at the Panter X-ray Test Facility. A description of the instrument calibration will be presented. The spectrometer is characterized by a full physical model. The physical model of the spectral reflectivity of the gratings will be described. It is based on the vector solution to Maxwell's equations, and it successfully reproduces the ground calibration data. The grating model is included with the physical models of each component along the optical path to construct the effective area model of the full spectrometer. The effective area model and comparisons with the ground and in-flight calibration data will also be described. The Reflection Grating Spectrometer can be used for high-resolution spectroscopy of X-ray emitting plasmas in a range of astophysical settings. The discrete features in the observed spectra are sensitive to the physical conditions of the emitting plasma. These features can therefore be used to quantitatively measure the temperature, density, velocity, and geometry of the material. This thesis will describe the application of high-resolution spectroscopy to the study of accretion-powered sources. The spectral analysis of two low-mass X-ray binaries will be presented. The first is EXO 0748-67, which was observed with XMM-Newton . The second is 4U 1822-37, which was observed with the Chandra X-ray Observatory.

Cottam, Jean

2001-09-01

89

A tower concept for the off-plane x-ray grating spectrometer for the International X-ray Observatory  

NASA Astrophysics Data System (ADS)

An Off-Plane X-ray Grating Spectrometer (OP-XGS) concept is being developed to meet the needs of the International X-ray Observatory (IXO). The OP-XGS will provide the required spectral resolution of R >3000 over the 0.3 - 1 keV band with >1000 cm2 effective collecting area, using experience gained with the current generation of reflection gratings already flown on rocket experiments. We have developed several potential configurations that meet or exceed these requirements. This paper will focus on the mechanical design and requirements for one of these configurations, the "tower" concept. This configuration mounts the grating modules to the instrument platform via a tower, allowing direct alignment with the camera module. This reduces the complexity of the alignment problem while also minimizing the overall mass of the XGS. We have developed an initial interface concept and resource requirements for this option to be reviewed by the mission teams for design drivers. We contrast the resource requirements for this concept with those required for other concepts which have been reviewed by the OP-XGS team. Further, we have identified those portions of the tower design concept that will require potential technology demonstration to reach TRL 6 prior to the Preliminary Design Review.

Casement, Suzanne; McEntaffer, Randall L.; Cash, Webster; Johnson, Tim; Lillie, Charles; Dailey, Dean

2010-07-01

90

A Tower Concept for the Off-Plane X-ray Grating Spectrometer for the International X-ray Observatory  

NASA Astrophysics Data System (ADS)

An Off-Plane X-ray Grating Spectrometer (OP-XGS) concept is being developed to meet the needs of the International X-ray Observatory (IXO). The OP-XGS will provide the required spectral resolution of R >3000 over the 0.3 - 1 keV band with >1000 cm2 effective collecting area, using experience gained with the current generation of reflection gratings already flown on rocket experiments. We have developed several potential configurations that meet or exceed these requirements and the optical modeling of these designs is presented by Dr. Webster Cash elsewhere at this conference. This paper will focus on the mechanical design and requirements for one of these configurations, the "tower” concept. This configuration mounts the grating modules to the instrument platform via a tower, allowing direct alignment with the camera module. This reduces the complexity of the alignment problem while also minimizing the overall mass of the XGS. We have developed an initial interface concept and resource requirements for this option to be reviewed by the mission teams for design drivers. We contrast the resource requirements for this concept with those required for other concepts which have been reviewed by the OP-XGS team. Further, we have identified those portions of the tower design concept that will require potential technology demonstration to reach TRL 6 prior to sensor Preliminary Design Review.

Casement, L. Suzanne; McEntaffer, R.; Cash, W.; Johnson, T.; Lillie, C.

2010-02-01

91

The CESAR Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

CESAR (Compact Echelle Spectrograph for Aeronomic Research) is an NSF MRI-funded instrument being constructed in the Molecular Physics Laboratory at SRI International. This spectrograph is patterned after instruments in use at the Keck telescopes on Mauna Kea, which generate sky spectra that have proven to be of great aeronomical value. CESAR is designed to be re-locatable, with initial measurements planned for high latitudes, in contrast to the Keck equatorial site. CESAR is to be operated remotely, continuously collecting data in real time. Initial measurements have been carried out with a laboratory N2 discharge, generating an aurora-like spectrum. The N2 1PG system was recorded at a resolution close to the design figure of 20,000, and the spectrum has been accurately simulated. The work was supported by NSF grant ATM-0723232.

Grill, M.; Kendall, E. A.; Slanger, T. G.

2011-12-01

92

Design and Construction of a Medium Resolving, Power Scanning, Grating Spectrometer.  

National Technical Information Service (NTIS)

A scanning Ebert-Fastie spectrometer was designed and built for the Optical Physics and Sensors Laboratory of the Naval Postgraduate School. Optical design was done with two commercially available optical design software packages, OSLO LT by Sinclair Opti...

J. E. Hassett

1999-01-01

93

Colorado High-resolution Echelle Stellar Spectrograph (CHESS)  

NASA Astrophysics Data System (ADS)

We discuss the design of a new high-efficiency, high-resolution far ultraviolet echelle spectrograph. Our project concentrates on utilizing new technologies for gratings and detectors to reduce the impact of scattered light and maximize quantum efficiency over a large bandpass. This program will enable advances in a vast number of astrophysical subjects. Topics ranging from protoplanetary disks to the intergalactic medium can be addressed by incorporating such a spectrograph into a future, long-duration mission.

Beasley, Matthew; Burgh, Eric; France, Kevin

2010-07-01

94

A study of electron-multiplying CCDs for use on the International X-ray Observatory off-plane x-ray grating spectrometer  

Microsoft Academic Search

CCDs are regularly used as imaging and spectroscopic devices on space telescopes at X-ray energies due to their high quantum efficiency and linearity across the energy range. The International X-ray Observatory's X-ray Grating Spectrometer will also look to make use of these devices across the energy band of 0.3 keV to 1 keV. At these energies, when photon counting, the

James H. Tutt; Andrew D. Holland; Neil J. Murray; David J. Hall; Randall L. McEntaffer; James Endicott; Mark Robbins

2010-01-01

95

Normal-incidence efficiencies of multilayer-coated laminar gratings for the extreme-ultraviolet imaging spectrometer on the solar-B mission.  

PubMed

The normal-incidence efficiencies of two laminar gratings and the reflectances of two parabolic mirrors with matching multilayer coatings were measured by monochromatic synchrotron radiation and were compared with modeling calculations. These optics were developed for the Extreme-Ultraviolet Imaging Spectrometer to be launched on the Japanese Solar-B mission. Each optic has two sectors coated with Mo/Si multilayers that reflect the 17-21-nm and 25-29-nm wave bands at normal incidence. The measured peak grating efficiencies are in the 8%-12% range and are in good agreement with efficiency calculations that account for the effects of groove profile and the microroughness as determined by atomic force microscopy. PMID:15015527

Seely, John F; Brown, Charles M; Windt, David L; Donguy, Soizik; Kjornrattanawanich, Benjawan

2004-03-01

96

A Spatial Heterodyne Spectrometer for Plasma Spectroscopy  

NASA Astrophysics Data System (ADS)

Spatial Heterodyne Spectrometer (SHS) designs will revolutionize interferometric spectroscopy in the VUV. Advantages of interferometric spectrometers include: (1) a very high spectral resolving power with a large etendue, (2) excellent absolute wavenumber accuracy, (3) extremely broad spectral coverage, and (4) high data collection rates. Interferograms from a conventional Fourier transform spectrometer (Michelson interferometer) are recorded as a function of time using a single channel detector while moving a mirror. Interferograms from an SHS are spread in space across a detector array. The lack of moving parts means that an SHS is compatible with low duty cycle, transient sources common in the VUV. Our SHS has a CaF2 beamsplitter and a matched pair of very coarse (23.2 groove/mm) echelle gratings blazed for 63.5 . Key mechanical components have temperature compensated designs and many parts, including the entire optical bread board, are made of Invar for long term phase stability. The 96 mm wide gratings are compatible with a theoretical limit-of-resolution of 0.058 cm-1 (inverse maximum path difference of 2 x 9.6 cm x sin 63.5 ) using a symmetric interferogram. The quality of interferograms recorded with a low resolution test camera indicated that the optics and mountings is satisfactory. First results with the full resolution 4 Mega-pixel VUV compatible CCD camera will be reported.

Lawler, J. E.; Labby, Z.; Roesler, F. L.; Harlander, J.

2006-10-01

97

A radial velocity spectrometer for the Automated Planet Finder Telescope at Lick Observatory  

NASA Astrophysics Data System (ADS)

The Ken and Gloria Levy Spectrometer is being constructed at the Instrument Development Laboratory (Technical Facilities) of UCO/ Lick Observatory for use on the 2.4 meter Automated Planet Finder Telescope at Mt. Hamilton. The mechanical design of the instrument has been optimized for precision Doppler measurements. A key component of the design is the space-frame structure that contains passive thermal compensation. Determinate hexapod structures are used to mount the collimator, prism, and echelle grating. In this paper we describe the instrument mechanical design and some features that will help it detect rocky planets in the habitable zone.

Radovan, Matthew V.; Cabak, Gerald F.; Laiterman, Lee H.; Lockwood, Christopher T.; Vogt, Steven S.

2010-07-01

98

The opto-mechanical design of the Colorado High-resolution Echelle Stellar Spectrograph (CHESS)  

NASA Astrophysics Data System (ADS)

We present the Colorado High-resolution Echelle Stellar Spectrograph (CHESS) sounding rocket payload. The design uses a mechanical collimator made from a grid of square tubing, an objective echelle grating, a holographically-ruled cross-disperser, a new 40 mm MCP with a cross strip anode or a delta-doped 3.5k x 3.5k CCD detector. The optics are suspended using carbon fiber rods epoxied to titanium inserts to create a space frame structure. A preliminary design is presented.

Kane, Robert; Beasley, Matthew; Green, James; Burgh, Eric; France, Kevin

2011-09-01

99

VIRTIS: Visible Infrared Thermal Imaging Spectrometer for the Rosetta mission  

NASA Astrophysics Data System (ADS)

The visible infrared thermal imaging spectrometer (VIRTIS) is one of the principal payloads to be launched in 2003 on ESA's Rosetta spacecraft. Its primary scientific objective s are to map the surface of the comet Wirtanen, monitor its temperature, and identify the solids and gaseous species on the nucleus and in the coma. VIRTIS will also collet data on two asteroids, one of which has been identified as Mimistrobell. The data is collected remotely using a mapping spectrometer co-boresighted with a high spectral resolution spectrometer. The mapper consists of a Shafer telescope matched to an Offner grating spectrometer capable of gathering high spatial, medium spectral resolution image cubes in the 0.25 to 5 micrometers waveband. The high spectral resolution spectrometer uses an echelle grating and a cross dispersing prism to achieve resolving powers of 1200 to 300 in the 1.9 to 5 micrometers band. Both sub-systems are passively cooled to 130 K and use two Sterling cycle coolers to enable two HgCdTe detector arrays to operate at 70 K. The mapper also uses a silicon back-side illuminated detector array to cover the ultra-violet to near-infrared optical band.

Reininger, Francis M.; Coradini, Angioletta; Capaccioni, Fabrizio; Capria, M. T.; Cerroni, Priscilla; de Sanctis, M. C.; Magni, G.; Drossart, P.; Barucci, M. A.; Bockelee-Morvan, D.; Combes, Jean-Michel; Crovisier, J.; Encrenaz, T.; Reess, J.; Semery, A.; Tiphene, Didier; Arnold, Gabriele; Carsenty, Uri; Michaelis, H.; Mottola, S.; Neukum, G.; Peter, G.; Schade, Ulrich; Taylor, Fredric W.; Calcutt, S. B.; Vellacott, Tim; Venters, P.; Watkins, R. E.; Bellucci, Giancarlo; Formisano, Vittorio; Angrilli, Francesco; Bianchini, Gianandrea; Saggin, Bortolino; Bussoletti, E.; Colangeli, L.; Mennella, Vito; Fonti, S.; Bibring, J.-P.; Langevin, Yves; Schmitt, B.; Combi, M.; Fink, U.; McCord, Thomas B.; Ip, Wing; Carlson, Robert W.; Jennings, Donald E.

1996-11-01

100

Externally Dispersed Interferometry with the Lick Observatory Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

We demonstrate stellar and solar measurements of full-bandwidth echelle spectra using an externally dispersed interferometer (EDI). Spectral resolution of ~120k has been obtained using the ~60k resolution CAT facility at the Lick Observatory. The EDI is a series combination of a fixed delay interferometer and a grating spectrograph that increases the spectrograph's effective resolution by factors of 2 to 3. EDI uses a heterodyning effect to shift the input spectrum's high spectral resolution information to lower spatial frequencies that are less sensitive to the resolution limit caused by the spectrograph slit size and by the Nyquist limit of the detector. The resolution-boosted spectra is obtained by numerically reversing the heterodyning effect and combining these data with the ordinary spectrum simultaneously acquired within the EDI data. The interferometer fringes imprinted on the spectrum are exactly periodic in frequency space and acts as a fiducial net that uniformly covers the entire echelle bandwidth. Instrumental distortions that deviate the stellar signal also deviate these fiducial fringes, so the measurement, in comparison to a classical echelle data, is extremely robust to beam profile errors. Our method uses a uniform-phase interferometer fringe at the spectrograph entrance slit. Therefore the spectrograph may use either a 2d-echelle or slit-imaging format. The EDI has applications in Doppler radial velocimetry and high resolution spectroscopy. Work was partially supported by CalSpace/Lockheed, and NASA SARA research grants NAG5-9091 and NAG5-3051. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Erskine, D. J.; Edelstein, J.

2002-12-01

101

Buckling failure of the automated planet finder spectrometer determinate spaceframe  

NASA Astrophysics Data System (ADS)

The Ken and Gloria Levy Spectrometer is now operational at a new 2.4 meter telescope on Mt. Hamilton. Together the spectrometer and telescope comprise the Automated Planet Finder (APF), a radial velocity instrument. A catastrophic failure occurred during transit as the instrument was being shipped to the observatory. Several struts buckled in the space frame that supported the echelle grating. This event has caused UCO/Lick to re-evaluate design methodology and how engineering safety factors apply to this type of structure. This paper describes the shipping container design, events during shipment, the failure mechanism, testing and analysis of a remedy, and its implementation. We also suggest design changes to prevent similar failures in the future.

Radovan, Matthew V.; Cabak, Gerald F.

2012-09-01

102

Spectroscopic evaluation of three different gratings used for a flat-field extreme ultraviolet spectrometer to monitor ?n=1 transitions from medium-Z impurities in 10-30 A?  

NASA Astrophysics Data System (ADS)

Spectral characteristics of varied line spacing 2400 grooves/mm gratings used for a flat-field extreme ultraviolet spectrometer have been evaluated to monitor ?n=1 (n=2-3) transitions from medium-Z impurities in 10-30 A?, where many spectral lines from metallic impurities closely exist. For this purpose emission spectra of the ?n=1 transitions from partially L-shell-ionized Ti and Fe have been measured in large helical device. At first, a ruled and a holographic grating were utilized for the comparative study. Both gratings suppressed higher order light effectively but spectral sensitivity was much higher for the holographic grating. The ruled grating, however, attained better spectral resolution (0.083 A? at 18.97 A?) in the 10-100 A? range compared to that (0.130 A?) of the holographic grating. After that a recently developed new holographic grating with different laminar shapes and line spacings has attempted to improve the spectral resolution. As a result, it has considerably improved the spectral resolution in the 10-30 A? range, i.e., ~0.090 A?. However, it is found that the experimentally obtained spectral resolution is quit poor compared to the computationally simulated one, suggesting a technical difficulty in manufacturing exactly the varied line spacing of the holographic grating at such a short wavelength range.

Chowdhuri, Malay Bikas; Morita, Shigeru; Goto, Motoshi; Sasai, Hiroyuki

2008-10-01

103

TRAFICOS - an Echelle Zeeman spectrograph  

NASA Astrophysics Data System (ADS)

We describe the TRAnsportable FIbre COupled echelle Spectrograph (TRAFICOS) equipped with a Zeeman analyzer and manufactured mainly for the observation of stellar magnetic fields. The spectrograph, designed at the Astrophysikalisches Institut Potsdam and constructed at the Th{u}ringer Landessternwarte Tautenburg, is laid out in a quasi-Littrow configuration. The part attached to the Nasmyth focus of the 2 m telescope contains the telescope adapter for the fibre input and output of the star and calibration light, the cases for the flatfield and the wavelength calibration, and the Zeeman analyzer. The optical scheme and the reduction software are mentioned in some details and the first results of the determination of the magnetic field and radial velocity of several stars are given showing the performance of the device in comparison with existing data.

Hildebrandt, G.; Scholz, G.; Rendtel, J.; Woche, M. Lehmann, H.

1997-08-01

104

High-Resolution Spectroscopy of the X-Ray-photoionized Wind in Cygnus X-3 with the Chandra High-Energy Transmission Grating Spectrometer.  

PubMed

We present a preliminary analysis of the 1-10 keV spectrum of the massive X-ray binary Cygnus X-3, obtained with the high-energy transmission grating spectrometer on the Chandra X-Ray Observatory. The source reveals a richly detailed discrete emission spectrum, with clear signatures of photoionization-driven excitation. Among the spectroscopic novelties in the data are the first astrophysical detections of a number of He-like "triplets" (Si, S, Ar) with emission-line ratios characteristic of photoionization equilibrium, fully resolved narrow radiative recombination continua of Mg, Si, and S, the presence of the H-like Fe Balmer series, and a clear detection of an approximately 800 km s-1 large-scale velocity field as well as an approximately 1500 km s-1 FWHM Doppler broadening in the source. We briefly touch on the implications of these findings for the structure of the Wolf-Rayet wind. PMID:10770708

Paerels; Cottam; Sako; Liedahl; Brinkman; van Der Meer RL; Kaastra; Predehl

2000-04-20

105

Grating spectrometer system for beam emission spectroscopy diagnostics using high-energy negative-ion-based neutral beam injection on LHD  

SciTech Connect

A beam emission spectroscopy (BES) system was developed for density gradient and fluctuation diagnostics in the Large Helical Device (LHD). In order to cover the large Doppler shift of the H{alpha} beam emission because of the high-energy negative-ion-based neutral beam atom (acceleration voltage V{sub acc}=90-170 kV) and the large motional Stark splitting due to the large vxB field (magnetic field B=3.0 T), a grating spectrometer was used instead of a conventional interference filter system. The reciprocal linear dispersion is about 2 nm/mm, which is sufficient to cover the motional Stark effect spectra using an optical fiber with a diameter of 1 mm.

Kado, S. [School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Oishi, T. [Graduate School/School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yoshinuma, M.; Ida, K. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

2010-10-15

106

Fabrication and testing of a silicon immersion grating for infrared spectroscopy  

SciTech Connect

Recent advances in silicon micromachining techniques (e.g. anisotropic etching) allow the fabrication of very coarse infrared echelle gratings. When used in immersion mode, the dispersion is increased proportionally to the refractive index. This permits a very significant reduction in the overall size of a spectrometer while maintaining the same resolution. We have fabricated a right triangular prism (30{times}60{times}67 mm with a rectangular entrance face 30{times}38 mm) from silicon with a grating etched into the face of the hypotenuse. The grating covers an area of 32 mm by 64 mm and has a 97.5 PM periodicity with a blaze angle of 63.4{sup o}. The groove surfaces are very smooth with a roughness of a few manometers. Random defects in the silicon are the dominant source of grating scatter ({approx} 12% at 3.39 {mu}m). We measure a grating ghost intensity of 1.2%. The diffraction peak is quite narrow, slightly larger than the Airy disc diameter at F/12. However due to wavefront aberrations, perhaps 15--20% of the diffracted power is in the peak with the rest distributed in a diameter roughly five times the Airy disc.

Kuzmenko, P.J.; Ciarlo, D.R.; Stevens, C.G.

1994-07-25

107

Data Pipelines for the TRES Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

An IRAF-based processing pipeline has been written to reduce spectra from the Smithsonian Astrophysical Observatory's TRES (Tillinghast Reflector Echelle Spectrograph) two-fiber echelle spectrograph on Mt. Hopkins in Arizona. A modular system was written in IRAF so that the same software could be used at the telescope for quick-look processing and later with more accuracy for scientific processing. IRAF tasks developed for the SAO FAST long-slit and Hectospec multi-fiber spectrographs, as well as NOAO-developed echelle tasks, were adapted for this instrument.

Mink, D. J.

2011-07-01

108

High-resolution spectrometer: solution to the axial resolution and ranging depth trade-off of SD-OCT  

NASA Astrophysics Data System (ADS)

We demonstrate a cross-dispersed spectrometer for Spectral Domain Optical Coherence Tomography (SD-OCT). The resolution of a conventional SD-OCT spectrometer is limited by the available sizes of the linear array detectors. The adverse consequences of this finite resolution is a trade-off between achieving practical field of view (i.e. ranging depth) and maintaining high axial resolution. Inspired by spectrometer designs for astronomy, we take advantage of very high pixel-density 2D CCD arrays to map a single-shot 2D spectrum to an OCT A-scan. The basic system can be implemented using a high-resolution Echelle grating crossed with a prism in a direction orthogonal to the dispersion axis. In this geometry, the interferometric light returning from the OCT system is dispersed in two dimensions; the resulting spectrum can achieve more pixels than a traditional OCT spectrometer (which increases the ranging depth) and maintains impressive axial resolution because of the broad bandwidth of the detected OCT light. To the best of our knowledge, we present the first demonstration of OCT data using an Echelle-based cross-dispersed spectrometer. Potential applications for such a system include high-resolution imaging of the retina or the anterior segment of the eye over extended imaging depths and small animal imaging.

Marvdashti, Tahereh; Lee, Hee Yoon; Ellerbee, Audrey K.

2013-03-01

109

Study of keV radiation properties of Mo and Ti X-pinch plasma sources using a pinhole transmission grating spectrometer  

NASA Astrophysics Data System (ADS)

The properties of keV x-ray radiations from Mo and Ti X-pinch plasma sources at the current of 800 kA were investigated by a pinhole transmission grating spectrometer. The spectrometer was characterized by a high linear dispersion rate (2.9 A?/mm), and from its time-integrated diffraction images, rich information about the X-pinch sources (e.g., source number, source size, and absolute spectra) could be obtained. Multiple hot spots were produced in all the Mo tests with loads made of two or four 25 ?m wires with or without a shunt wire, and obvious increases both in the radiation intensity and in the source size around the spectral region of 2.6 keV were observed. In Ti X-pinch tests, a single keV x-ray burst with a source size of ~200 ?m and a time duration of ~200 ps in full width at half maximum was obtained using a load made of two 50 ?m wires plus a shunt wire. The intensity of x-rays decreased sharply from ~1011 photon eV-1 sr-1 at 1 keV to ~108 photon eV-1 sr-1 at 4 keV. The energy-dependent source size in the band of 1-4 keV is less than 100 ?m and seemed to shrink quickly as x-ray energy increases.

Li, Jing; Deng, Jian-Jun; Xie, Wei-Ping; Huang, Xian-Bin; Yang, Li-Bing; Zhou, Shao-Tong; Zhu, Xiao-Li; Duan, Shu-Chao; Zhang, Si-Qun; Dan, Jia-Kun

2010-07-01

110

On-chip interrogation of a silicon-on-insulator microring resonator-based ethanol vapor sensor with an arrayed waveguide grating (AWG) spectrometer  

NASA Astrophysics Data System (ADS)

Silicon -on -insulator (SOI) optical microring resonators fabricated with the standard CMOS fabrication technology have recently gained considerable attention for energy efficient, compact and low cost biomedical and environmental sensing applications. High sensitivity to the surrounding refractive index variations, high compactness, direct wavelength multiplexing capabilities, simplicity, and the promise for mass fabrication are among the interesting features supported by SOI microring resonators. On the other hand, despite the strong case for microring resonators for sensing, there exist some issues which need to be addressed in order to ensure the feasibility of such sensors. One major limitation currently is the cost of optical sources and /or spectrum analyzers required to drive and interrogate these sensors. Either expensive light sources or spectrum analyzers are usually used with sensors built around microring resonators. An attractive approach to address this problem is the use of on-chip spectrometers along with cheap broadband light sources. We experimentally demonstrate on-chip interrogation of an SOI microring resonator based gas sensor with a compact Arrayed Waveguide Grating (AWG) spectrometer. We have designed and fabricated a 200GHz AWG with strongly overlapping output channels, and used it to interrogate the wavelength shift from a ring resonator based ethanol vapor sensor on the same chip. Ethanol vapor concentrations in 100-1000ppm range are readily detected by monitoring the intensity ratio between two adjacent AWG channels to which the microring resonance overlaps. Such an integrated sensor-interrogator approach is presented as an alternative to the current costly and off-chip read-out systems used for ring resonator based sensors.

Yebo, Nebiyu A.; Bogaerts, Wim; Hens, Zeger; Baets, Roel

2012-02-01

111

A study of electron-multiplying CCDs for use on the International X-ray Observatory off-plane x-ray grating spectrometer  

NASA Astrophysics Data System (ADS)

CCDs are regularly used as imaging and spectroscopic devices on space telescopes at X-ray energies due to their high quantum efficiency and linearity across the energy range. The International X-ray Observatory's X-ray Grating Spectrometer will also look to make use of these devices across the energy band of 0.3 keV to 1 keV. At these energies, when photon counting, the charge generated in the silicon is close to the noise of the system. In order to be able to detect these low energy X-ray events, the system noise of the detector has to be minimised to have a sufficient signal-to-noise-ratio. By using an EM-CCD instead of a conventional CCD, any charge that is collected in the device can be multiplied before it is read out and as long as the EM-CCD is cool enough to adequately suppress the dark current, the signal-to-noise ratio of the device can be significantly increased, allowing soft X-ray events to be more easily detected. This paper will look into the use of EM-CCDs for the detection of low energy X-rays, in particular the effect that using these devices will have on the signal to noise ratio as well as any degradation in resolution and FWHM that may occur due to the additional shot noise on the signal caused by the charge packet amplification process.

Tutt, James H.; Holland, Andrew D.; Murray, Neil J.; Hall, David J.; McEntaffer, Randall L.; Endicott, James; Robbins, Mark

2010-07-01

112

Calibration and characterization of HETG grating elements at the MIT X-Ray Grating Evaluation Facility  

Microsoft Academic Search

The high energy transmission grating spectrometer (HETGS) of the Advanced X-Ray Astrophysics Facility (AXAF) will include 336 gratings, of period 2000 angstrom and 4000 angstrom. The flight gratings have entered production, and preliminary tests for verification and calibration have begun. We present the current status of the x-ray tests at MIT, focusing on diffraction efficiency measurements and a grating tilt

Kathryn A. Flanagan; Daniel Dewey; Leonard Bordzol

1995-01-01

113

Far-ultraviolet imaging spectrograph and scanning grating spectrometers for the Remote Atmospheric and Ionospheric Detection System  

SciTech Connect

The Remote Atmospheric and Ionospheric Detection System (RAIDS) experiment is an optical remote sensing platform consisting of eight sensors, (spectrographs, spectrometers, and photometers) covering the wavelength range 550 to 8744 [angstrom]. RAIDS employs a mechanical scan platform to view the Earth's limb and measure line-of-sight column emission from tangent altitudes from 50 to 750 km. These measurements provide vertical profiles of atmospheric dayglow and nightglow from the mesosphere to the upper regions of the F-region ionosphere. RAIDS will be flown on the National Oceanographic and Atmospheric Administration (NOAA) J weather satellite through the auspices of the US Air Force Space Test Program. The RAIDS wavelength and altitude coverage allows remote sensing of the major and many minor constituents in the thermosphere and ionosphere. These measurements will be used as part of a proof of concept for remote sensing of ionospheric and neutral density profiles. The RAIDS database will be used to study composition, thermal structure, and couplings between the mesosphere, thermosphere, thermal structure, and couplings between the mesosphere, thermosphere, and ionosphere. RAIDS is a joint venture of the Naval Research Laboratory (NRL) and the Aerospace Corporation. The authors describe the subset of RAIDS instruments developed at NRL covering the far to near UV regions (1,300 to 4,000 [angstrom]).

McCoy, R.P.; Meier, R.R.; Wolfram, K.D.; Picone, J.M.; Thonnard, S.E.; Fritz, G.G.; Morrill, J.S. (Naval Research Lab., Washington, DC (United States). E.O. Hulburt Center for Space Research); Hardin, D.A. (Computational Physics Inc., Annandale, VA (United States)); Christensen, A.B.; Kayser, D.C.; Pranke, J.B.; Straus, P.R. (Aerospace Corp., Los Angeles, CA (United States). Space and Environment Technology Center)

1994-02-01

114

Far-ultraviolet imaging spectrograph and scanning grating spectrometers for the Remote Atmospheric and Ionospheric Detection System  

NASA Astrophysics Data System (ADS)

The Remote Atmospheric and Ionospheric Detection System (RAIDS) experiment is an optical remote sensing platform consisting of eight sensors, (spectrographs, spectrometers, and photometers) covering the wavelength range 550 to 8744 angstroms. RAIDS employs a mechanical scan platform to view the Earth's limb and measure line-of-sight column emission from tangent altitudes from 50 to 750 km. These measurements provide vertical profiles of atmospheric dayglow and nightglow from the mesosphere to the upper regions of the F-region ionosphere. RAIDS will be flown on the National Oceanographic and Atmospheric Administration (NOAA) J weather satellite through the auspices of the U.S. Air Force Space Test Program. The RAIDS wavelength and altitude coverage allows remote sensing of the major and many minor constituents in the thermosphere and ionosphere. These measurements will be used as part of a proof of concept for remote sensing of ionospheric and neutral density profiles. The RAIDS database will be used to study composition, thermal structure, and couplings between the mesosphere, thermosphere, and ionosphere. RAIDS is a joint venture of the Naval Research Laboratory (NRL) and The Aerospace Corporation. We describe the subset of RAIDS instruments developed at NRL covering the far to near UV regions (1300 to 4000 angstroms).

McCoy, Robert P.; Meier, Robert R.; Wolfram, Kenneth D.; Picone, J. M.; Thonnard, Stefan E.; Fritz, Gilbert G.; Morrill, Jeff S.; Hardin, David A.; Christensen, Andrew B.; Kayser, David C.; Pranke, James B.; Straus, Paul R.

1994-02-01

115

Multilayer-coated micro-grating array for x-ray phase-contrast imaging  

Microsoft Academic Search

X-ray imaging techniques based on grating interferometers rely on transmission gratings to detect x-ray refraction and scattering in a sample. Gratings periods below 2 microns are challenging to realize due to the high aspect ratio of the structures. We propose a method to fabricate transmission gratings with sub-micron periods over centimeter areas by multilayer coating of a staircase (echelle) substrate.

Susanna K. Lynch; Chian Liu; Lahsen Assoufid; Nicole Y. Morgan; Dumitru Mazilu; Eric Bennett; Camille K. Kemble; Han H. Wen

2011-01-01

116

The Accretion Disk Corona and Disk Atmosphere of 4U 1624-490 as Viewed by the Chandra-High Energy Transmission Grating Spectrometer  

NASA Astrophysics Data System (ADS)

We present a detailed spectral study (photoionization modeling and variability) of the "Big Dipper" 4U 1624-490 based on a Chandra-High Energy Transmission Grating Spectrometer (HETGS) observation over the ~76 ks binary orbit of 4U 1624-490 . While the continuum spectrum can be modeled using a blackbody plus power law, a slightly better fit is obtained using a single ? = 2.25 power-law partially (71%) covered by a local absorber of column density N_H Local=8.1_{-0.6}^{+0.7}× 10^{22} cm^{-2}. The data show a possible quasi-sinusoidal modulation with period 43+13 -9 ks that might be due to changes in local obscuration. Photoionization modeling with the XSTAR code and variability studies of the observed strong Fe XXV and Fe XXVI absorption lines point to a two-temperature plasma for their origin: a highly ionized component of ionization parameter ?hot ? 104.3 erg cm s-1 (T ~ 3.0 × 106 K) associated with an extended accretion disk corona of radius R ~ 3 × 1010 cm, and a less-ionized more variable component of ? ? 103.4 erg cm s-1 (T ~ 1.0 × 106 K) and ? ? 10^{3.1} erg cm s^{-1} (T ~ 0.9 × 106 K) coincident with the accretion disk rim. We use this, with the observed Fe XXV and Fe XXVI absorption line variations (in wavelength, strength, and width) to construct a viewing geometry that is mapped to changes in plasma conditions over the 4U 1624-490 orbital period.

Xiang, Jingen; Lee, Julia C.; Nowak, Michael A.; Wilms, Jörn; Schulz, Norbert S.

2009-08-01

117

Linear wavelength spectrometer  

Microsoft Academic Search

Generally, a spectrometer uses a diffraction grating to spread the spectral components of a light incident on the diffraction grating on a one-dimensional detector. The detector is composed of pixels linearly distributed along a line. However, the diffracted light is not spread linearly on the detector which means that the wavelength on pixel 1 is not linearly correlated with the

Simon Thibault

2001-01-01

118

GHRS Cycle 5 Echelle Wavelength Monitor  

NASA Astrophysics Data System (ADS)

This proposal defines the spectral lamp test for Echelle A. It is an internal test which makes measurements of the wavelength lamp SC2. It calibrates the carrousel function, Y deflections, resolving power, sensitivity, and scattered light. The wavelength calibration dispersion constants will be updated in the PODPS calibration data base. This proposal defines the spectral lamp test for Echelle B. It is an internal test which makes measurements of the wavelength lamp SC2. It calibrates the carrousel function, Y deflections, resolving power, sensitivity, and scattered light. The wavelength calibration dispersion constants will be updated in the PODPS calibration data base. It will be run every 4 months. The wavelengths may be out of range according to PEPSI or TRANS. Please ignore the errors.

Soderblom, David

1995-07-01

119

High-resolution UV echelle spectrograph for environmental sensing  

NASA Astrophysics Data System (ADS)

Resonance Raman spectroscopy is an enhanced Raman technique that can be used to selectively identify a particular analyte in complex matrices. Resonance Raman requires the excitation laser to overlap with an absorption band of the analyte of interest. Since analytes have diverse absorption spectra, dilute concentrations may be detected when resonantly enhanced. A significant portion of interesting molecules absorb only in the UV; unfortunately current UV Raman instrumentation for scientifically desirable spectral resolution is large and costly. In the area of Homeland Defense, explosives, nerve agents, amino acid residues (for toxin analysis) and nucleic acids (for DNA detection and identification of bacteria) are all enhanced using UV laser sources. EIC Laboratories has developed a more user-friendly UVRRS spectrograph that is based upon the use of an echelle grating. The spectrograph has a footprint of 7" x 11" and is capable of providing 4 cm-1 resolution over a fairly wide spectral range. The spectrograph design and spectra from analytes of particular relevance will be presented.

Clauson, Susan L.; Christesen, Steven D.; Spencer, Kevin M.

120

URSIES: an Ultravariable Resolution Single Interferometer Echelle Scanner.  

PubMed

A Fabry-Perot interferometer in a Ramsay mount is used in tandem with an echelle Hilger monochromator with pinholes instead of slits. The instrument, URSIES, is enclosed within a pressure chamber filled with Freon. Photoelectric pulse counting techniques and pressure scanning are used to record the spectrum. This design has four basic advantages: (1) The resolution of the scanner is variable from 5.0 A to 0.005 A, and the effective wavelength range is quite broad, from 3500 A to 13,000 A. (2) A light gain of ten over conventional grating scanners at resolutions of 0.1 A or better is achieved. (3) Very low levels of light from outside the wavelength passband reach the detector; for a resolution of 0.03 A at 6000 A this level is 5%. (4) There are very low levels of scattered light from the pinholes when extended sources are observed. The scattered light from the instrument at the edge of the solar disk is found to be less than 1% from 4000 A to 11,000 A. Measurements demonstrating these advantages are discussed. PMID:20119110

Wyller, A A; Fay, T

1972-05-01

121

The Spectrometer  

ERIC Educational Resources Information Center

|In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating), and I began to realize that inside was some familiar old…

Greenslade, Thomas B., Jr.

2012-01-01

122

The Spectrometer  

ERIC Educational Resources Information Center

In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating), and I began to realize that inside was some familiar old…

Greenslade, Thomas B., Jr.

2012-01-01

123

The Spectrometer  

NASA Astrophysics Data System (ADS)

In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating1), and I began to realize that inside was some familiar old technology. In this paper I would like to discuss its ancestors.

Greenslade, Thomas B.

2012-03-01

124

Development of Infrared Spectrometers in Recent Years.  

National Technical Information Service (NTIS)

The paper outlines the technical development of infrared spectrometers, with emphasis on the characteristics and useful values of modern wide-angle prisms, simplified prisms, light filter-grating instruments, and prism-grating instruments. In addition, th...

Cheng I-Shan

1969-01-01

125

Silicon anamorphic gratings for IR high-resolution spectroscopy with future giant telescopes  

NASA Astrophysics Data System (ADS)

Future 30m telescopes provide enormous challenges for IR high resolution spectrograph design. The spectrograph collimated beam size will reach ~ 400 mm in order to reach R ~ 25,000 under 0.4 arcsec seeing-limited images. This beam size will push an IR spectrograph volume larger than that of the giant optical echelle spectrograph at 10m telescopes, e.g. the Keck HIRES is 6×6×4 m3 (Vogt et al. 1994). The cost would be enormous considering the entire instrument must be cooled to cryogenic temperatures to be feasible. Here we propose a new kind of IR spectrometer using silicon anamorphic immersion gratings as the main disperser. By operating silicon immersion gratings in an anamorphic immersion mode, the increase in spectral resolving power can be up to a factor of n2 or ~12 times at Brewster"s angle (Dekker 1987). Hence, to reach the same spectral resolution, the collimated beam size is reduced to ~33mm in diameter, which makes the design of the instrument relatively easy. The recent breakthrough in silicon immersion grating technology at Penn State has allowed us to routinely fabricate high quality silicon grisms and immersion gratings with sizes of up to 2 inches, <1% integrated scattered light, and diffraction-limited performance thanks to newly developed techniques. Silicon anamorphic immersion gratings with etched dimensions of ~4 inches are being developed at Penn State. The first grating will be available for testing in late 2002. Currently, industry can supply up to 12 inch diameter silicon ingots. We plan to develop a new tool to handle this large grating size in our state-of-the-art nanofabrication facility. A silicon anamorphic grating of this size can provide a seeing-limited (0.4 arcsec) spectral resolution of R ~ 30,000 or diffraction-limited spectral resolution of R ~ 750,000 at 2.2 microns. In this paper, technical issues related to the design of an anamorphic grating spectrograph are discussed.

Ge, Jian; Bernecker, John L.; McDavitt, Daniel L.; Miller, Shane

2003-01-01

126

Post - SM4 Flux Calibration of the STIS Echelle Modes  

NASA Astrophysics Data System (ADS)

Like all STIS spectroscopic modes, STIS echelle modes show a wavelength dependent decline in detector sensitivity with time. The echelle sensitivity is further affected by a time-dependent shift in the blaze function. To better correct the effects of the echelle sensitivity loss and the blaze function changes, we derive new baselines for echelle sensitivities from post-HST Servicing Mission 4 observations of the standard star G191-B2B. We present how these baseline sensitivities compare to pre-failure trends.

Bostroem, Azalee; Aloisi, A.; Bohlin, R. C.; Proffitt, C. R.; Osten, R. A.; Lennon, D.

2010-07-01

127

The GMT-CFA-CARNEGIE-CATOLICA LARGE EARTH FINDER (G-CLEF): A Fiber-fed, Optical Echelle Spectrograph For The Giant Magellan Telescope  

NASA Astrophysics Data System (ADS)

The GMT-CfA-Carnegie-Catolica Large Earth Finder (G-CLEF) is a fiber-fed optical echelle spectrograph in concept design study phase for first light at the Giant Magellan Telescope. G-CLEF is designed to be a multipurpose echelle spectrograph that operates in a number of modes so as to enable precision radial velocity (RV) measurements, detailed abundance studies, isotopic abundance measurements and probe the IGM and ISM at high Z. Four resolution modes are implemented with image and pupil slicing. Extremely precise RV will be achieved by vacuum enclosing the spectrograph, with advanced fiber scrambling and state-of-the-art calibrators, especially ultra stabilized etalons and possibly laser frequency combs. The optical design is a asymmetric white pupil design with two camera arms splitting the 350 nm - 950 nm passband into red and blue channels. G-CLEF will have an extremely large, mosaiced echelle grating and volume phase holograph cross dispersers.

Szentgyorgyi, Andrew; Furesz, G.; Frebel, A.; Geary, J.; Evans, I.; Norton, T.; Hertz, E.; DePonte Evans, J.; Jordan, A.; Guzman, D.; Epps, H.; Barnes, S.; Crane, J.

2011-01-01

128

The Limitations of Precise Echelle Data Reduction  

NASA Astrophysics Data System (ADS)

The most complicated task in echelle data reduction is the removal of the blaze function. The usual way of doing this is the division by the extracted profile of flat field other star or the theoretical model. Such unblazing however is good only as a first approximation. There still remain residual structures giving after merging of orders wavy patterns in continuum shape. Their size - up to the 5% of continuum level - prevents the detailed study of line profile changes and can introduce considerable errors into equivalent width measurement especially on shallow wide lines or on resonance lines with wide wings spread over several echelle orders. The inconsistencies seem to be dependent on the physical state of the instrument (fiber bending temperature) and on the observing environment but due to their random behaviour a time consuming individual treatment of each spectrum is required to achieve reliable results. We give examples of such perturbed data from HEROS spectrograph obtained by an automatic pipeline as well as the overview of our attempts to improve the merging of orders manually.

Skoda, Petr; Slechta, Miroslav

129

Multilayer-coated micro-grating array for x-ray phase-contrast imaging  

NASA Astrophysics Data System (ADS)

X-ray imaging techniques based on grating interferometers rely on transmission gratings to detect x-ray refraction and scattering in a sample. Gratings periods below 2 microns are challenging to realize due to the high aspect ratio of the structures. We propose a method to fabricate transmission gratings with sub-micron periods over centimeter areas by multilayer coating of a staircase (echelle) substrate. The advantage of this approach is the high aspect ratio of multilayer coating and the large area of the echelle substrate. The staircase pattern is etched on the surface of a silicon wafer through anisotropic etching. Multiple layers are deposited on the horizontal surfaces of the stairs by magnetron sputtering in a single run. The layers alternate between two materials of different absorption coefficients or refractive indices. The layer thickness d is designed to be (stair height)/2N, where 2N is the total number of layers. The incident xray beam is parallel to the layers and oblique to the wafer surface. Each stair of the echelle substrate forms a micro grating of period 2d, and the array of micro gratings together act as a single grating over a large area given the right continuity conditions. The grating period potentially can be below 100 nm. We present theoretical description of wave diffraction by the grating array, and results of the first fabrication test with magnetron sputtering deposition.

Lynch, Susanna K.; Liu, Chian; Assoufid, Lahsen; Morgan, Nicole Y.; Mazilu, Dumitru; Bennett, Eric; Kemble, Camille K.; Wen, Han H.

2011-05-01

130

Echelle Spectrophotometry of the Orion Nebula  

NASA Astrophysics Data System (ADS)

We present echelle spectroscopy in the 3550 to 7010 A range for two positions of the Orion Nebula. The data were obtained with the 2.1-m telescope at Observatorio Astronomico Nacional in San Pedro Martir, Baja California. We have measured the intensities of several permitted lines of C(+) , N(+) , N(++) , O(0) , O(+) , Ne(0) , Si(+) , Si(++) which are excited by recombination and fluorescence. We have determined the electron temperature, the electron density and the ionic abundances using different intensity ratios. In particular the O(++) /H(+) abundance obtained by recombination lines is 40% higher than that obtained using forbidden [O III] lines. Moreover the C(++) /H(+) value derived from the recombination C II 4267 line is a factor of two higher than that derived in previous work for the same zone using C III] 1906+1909 collisionally excited lines. We estimate that a moderate value of t(2) = 0.025 +/- 0.015 can account for these discrepancies.

Peimbert, M.; Esteban, C.; Torres-Peimbert, S.; Escalante, V.

1996-12-01

131

Wavelength Calibration of the Hamilton Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

We present the wavelength calibration of the Hamilton Echelle Spectrograph at Lick Observatory. The main problem with the calibration of this spectrograph arises from the fact that thorium lines are absent in the spectrum of the presumed ThAr hollow-cathode lamp now under operation; numerous unknown strong lines, which have been identified as titanium lines, are present in the spectrum. We estimate the temperature of the lamp's gas which permits us to calculate the intensities of the lines and to select a large number of relevant Ti I and Ti II lines. The resulting titanium line list for the Lick hollow-cathode lamp is presented. The wavelength calibration using this line list was made with an accuracy of about 0.006 Å.

Pakhomov, Yu. V.; Zhao, G.

2013-10-01

132

Grating imaging scanning lithography for fabrication of large sized grating  

NASA Astrophysics Data System (ADS)

Diffraction grating is a high-resolution dispersion optical element. It has been widely used as the key component in optical spectroscopy, telecommunication multiplexing and laser systems, etc. Recently there is a growing demand for large-sized diffraction gratings in spectrometers industry, laser fusion facility, and its fabrication method is also a hot topic now. To fabricate large sized gratings, we have developed a grating imaging scanning lithography system. In this technology, the phase grating with jagged edge is used to generate diffractive beams and the spatial filter is used to select +/-1 order diffractive beams. Then two-beam interference on the substrate forms the grating fringes. At the same time, a 4f-system is used to form an identical image with clear boundary in the interference area. A high precision twodimensional mobile station, which enables the accurate positioning and move of the substrate, is utilized for complementary cyclical scanning, thus the image stitching errors are effectively eliminated. With this technology, we have fabricated a grating with period of 20?m and size of 100mm×100mm. In this paper the grating imaging scanning lithography procedure is described step by step. The principles and the experimental results are also explained in detail. With the characteristics of a simple structure, high energy utilization and stability, this new lithography technology should be an efficient way to fabricate large sized grating in the future.

Yu, Bin; Jia, Wei; Zhou, Changhe

2012-11-01

133

Performance of a laser frequency comb calibration system with a high-resolution solar echelle spectrograph  

NASA Astrophysics Data System (ADS)

Laser frequency combs (LFC) provide a direct link between the radio frequency (RF) and the optical frequency regime. The comb-like spectrum of an LFC is formed by exact equidistant laser modes, whose absolute optical frequencies are controlled by RF-references such as atomic clocks or GPS receivers. While nowadays LFCs are routinely used in metrological and spectroscopic fields, their application in astronomy was delayed until recently when systems became available with a mode spacing and wavelength coverage suitable for calibration of astronomical spectrographs. We developed a LFC based calibration system for the high-resolution echelle spectrograph at the German Vacuum Tower Telescope (VTT), located at the Teide observatory, Tenerife, Canary Islands. To characterize the calibration performance of the instrument, we use an all-fiber setup where sunlight and calibration light are fed to the spectrograph by the same single-mode fiber, eliminating systematic effects related to variable grating illumination.

Doerr, H.-P.; Kentischer, T. J.; Steinmetz, T.; Probst, R. A.; Franz, M.; Holzwarth, R.; Udem, Th.; Hänsch, T. W.; Schmidt, W.

2012-09-01

134

New On-Orbit Sensitivity Calibrationfor All STIS Echelle Modes  

NASA Astrophysics Data System (ADS)

On-orbit sensitivities for the 32 medium- and high-resolution STIS echelle secondarymodes were determined for the rst time using observations of the fundamental DAwhite dwarf standard star G191-B2B. Revised on-orbit sensitivities for the 12 mediumandhigh-resolution echelle prime modes based on observations of the same standardstar are also presented. We review the procedures and assumptions used to derive theadopted throughputs and implement them into the pipeline.

Aloisi, Alessandra; Bohlin, Ralph; Quijano, Jessica Kim

2007-01-01

135

High performance gratings for space applications  

NASA Astrophysics Data System (ADS)

Different earth-observation and scientific space missions have the need for special spectrometer gratings. As satellite instruments typically operate close to the technologically accessible limits also the realization of the respective gratings is extremely demanding. Critical parameters are the diffraction efficiency and its polarization dependency, the wavefront error introduced by the grating, stray-light performance, and usability in a space environment. We show that it is necessary to include technological considerations into the design and specification of the grating in order to achieve the optimal performance of the complete optical system. We demonstrate this approach by two examples. The first one is the design and fabrication of the grating for the Radial-Velocity-Spectrometer of the GAIA-mission of the ESA using a novel approach based on an effective medium sub-structure within one grating period. The second example is a high dispersion NIR-spectrometer grating for an earth observation mission. Such gratings are typically realized as immersed structures in order to maximize the dispersion. We show that the same optical performance can be achieved with gratings operating in the resonance domain which can be realized by electron-beam lithography as well.

Zeitner, U. D.; Michaelis, D.; Kley, E.-B.; Erdmann, M.

2010-04-01

136

Varied line-space grating for flat spectral response of coupling to single-mode fiber.  

PubMed

We use a planar linear grating with varied line-space grooves to introduce a tailored one-dimensional phase variation profile that results in an aberrated point-spread function at the focal plane. A design procedure for the period chirp map for such gratings is developed. As an example, we present theoretical and experimental results on a mechanically ruled, varied line-space echelle grating in single-mode fiber-coupled optical multiplexers in the wavelength region of 1545 nm. The varied line-space grating changes the multiplexer's Gaussian spectral response function to a flat-top dependence with reduced sensitivity to source laser wavelength drift. PMID:17268556

Huang, X-P; Spuler, Scott M; Sappey, Andrew D

2007-01-10

137

Parabolic telescope and spectrometer combination  

NASA Astrophysics Data System (ADS)

The properties of a nonfocusing collimating parabolic telescope are studied in detail by a ray-tracing method. The best optical quality with respect to coma and astigmatism is calculated for rays close to the optical axis of the telescope. For rectangular fields of view the borders are not sharp because of the aberration. A combination of a parabolic telescope and an echelle-type spectrometer gives very high spectral resolution. Wadsworth, Ebert-Fastie, and other types of spectrometers are equally well suited to be combined with this telescope. For some cases spot diagrams demonstrate the optical performance. In addition, diffraction by the aperture and its implications are discussed.

Schmidtke, G.; Henneberg, P.; Hager, K.-H.; Busch, F.; Reinhardt, D.

1980-06-01

138

Parabolic telescope and spectrometer combination.  

PubMed

The properties of a nonfocusing collimating parabolic telescope are studied in detail by a ray-tracing method. The best optical quality with respect to coma and astigmatism is calculated for rays close to the optical axis of the telescope. For rectangular fields of view the borders are not sharp because of the aberration. A combination of a parabolic telescope and an echelle-type spectrometer gives very high spectral resolution. Wadsworth, Ebert-Fastie, and other types of spectrometers are equally well suited to be combined with this telescope. For some cases spot diagrams demonstrate the optical performance. In addition, diffraction by the aperture and its implications are discussed. PMID:20221130

Schmidtke, G; Henneberg, P; Hager, K H; Busch, F; Reinhardt, D

1980-06-01

139

Planar waveguide spectrometer  

SciTech Connect

An integrated optic consisting of buried diffraction gratings and a planar waveguide was developed as an internal reflectance element for broad-band spectroscopic analysis of liquids. Polystyrene or tantalum pentoxide waveguides were deposited over a pair of diffraction gratings etched into the surface of a glass slide. Multiwavelength light was focused through the substrate onto the first grating. Component wavelengths were coupled into the waveguide and spatially dispersed by the second grating after propagating through the waveguide. A silicon photodiode array detector was used to collect the spectra data. Our goal is to produce a compact, rapid spectrometer having no moving parts that can take advantage of fiber optics and fast array detectors in the visible and near-infrared regions for industrial process control. The thin planar waveguide provides enhanced sensitivity to analyze weaker absorptions in the near-infrared. 10 refs., 5 figs.

Goldman, D.S.; White, P.L.; Anheier, N.C.

1990-07-01

140

Study of the image quality and stray light in the critical design phase of the Compact Echelle Spectrograph for Aeronomical Research (CESAR))  

NASA Astrophysics Data System (ADS)

The success of the high resolution nightglow studies conducted with the Keck telescopes on Mauna Kea and the Very Large Telescopes in Chile led to the design of the Compact Echelle Spectrograph for Aeronomical Research (CESAR). This is an echelle spectrograph with grating post-dispersion that will be dedicated to nightglow studies at high spectral resolution (R ~ 20000) between 300-1000 nm, and that will be easily deployable at different sites. The development of CESAR is conducted by SRI International, and INO is involved in the optical design and integration of the spectrograph camera, whose all-spherical form is based on the camera of the HIRES spectrograph at the Keck I telescope. The detailed optical design is used to calculate the position of the spectral elements on the detector, predict their image quality, and estimate the level of stray light. This paper presents the methodology used in these analyses.

Lavigne, Jean-François; Doucet, Michel; Wang, Min; Lacoursière, Jean; Grill, Martin; Melchiorri, Riccardo; Slanger, Tom G.; Kendall, Elizabeth

2010-07-01

141

A soft X-ray study of type I active galactic nuclei observed with Chandra high-energy transmission grating spectrometer  

NASA Astrophysics Data System (ADS)

We present the results of a uniform analysis of the soft X-ray spectra of 15 type I active galactic nuclei (AGN) observed with the high-resolution X-ray gratings onboard Chandra. We found that 10 out of the 15 AGN exhibit signatures of an intrinsic ionized absorber. The absorbers are photoionized and outflowing, with velocities in the range ~101 - 103 km s-1. The column density of the warm absorbing gas is ~1020-23 cm-2. Nine out of the 10 AGN exhibiting warm absorption are best fitted by multiple ionization components and three out of the 10 AGN require multiple kinematic components. The warm absorbing gas in our AGN sample has a wide range of ionization parameter, spanning roughly four orders of magnitude (? ~ 100-4 erg cm s-1) in total, and often spanning three orders of magnitude in the same gas. Warm absorber components with ionization parameter ? < 10 generate an unresolved transition array due to Fe in seven out of the 10 AGN exhibiting warm absorption. These low ionization state absorbers may also carry away the largest mass outflows from the AGN. The mass outflow rate depends critically on the volume filling factor of the gas, which cannot yet be directly measured. However, upper limits on the mass outflow rates for filling factors of unity can be much greater than the expected accretion rate on to the central supermassive black hole and filling factors as small as 1 per cent can give outflow rates comparable to the accretion rate. There appears to be a gap in the outflow velocities in our sample between ~300 and 500 km s-1, the origin of which is not clear. The outflow components with velocities below this gap tend to be associated with lower column densities than those with velocities above the gap.

McKernan, B.; Yaqoob, T.; Reynolds, C. S.

2007-08-01

142

Development of the Colorado High-resolution Echelle Stellar Spectrograph (CHESS)  

NASA Astrophysics Data System (ADS)

A key astrophysical theme that will drive future UV/optical space missions is the life cycle of cosmic matter, from the flow of intergalactic gas into galaxies to the formation and evolution of exoplanetary systems. Spectroscopic systems capable of delivering high resolution with low backgrounds will be essential to addressing these topics. Towards this end, we are developing a rocket-borne instrument that will serve as a pathfinder for future high-sensitivity, highresolution UV spectrographs. The Colorado High-resolution Echelle Stellar Spectrograph (CHESS) will provide 2 km s-1 velocity resolution (R = 150,000) over the 100 - 160 nm bandpass that includes key atomic and molecular spectral diagnostics for the intergalactic medium (H I Lyman-series, O VI, N V, and C IV), exoplanetary atmospheres (H I Lyman-alpha, O I, and C II), and protoplanetary disks (H2 and CO electronic band systems). CHESS uses a novel mechanical collimator comprised of an array of 10 mm x 10 mm stainless steel tubes to feed a low-scatter, 69 grooves mm-1 echelle grating. The cross-disperser is a holographically ruled toroid, with 351 grooves mm-1. The spectral orders can be recorded with either a 40 mm cross-strip microchannel plate detector or a 3.5k x 3.5k ?-doped CCD. The microchannel plate will deliver 30 ?m spatial resolution and employs new 64 amp/axis electronics to accommodate high count rate observations of local OB stars. CHESS is scheduled to be launched aboard a NASA Terrier/Black Brant IX sounding rocket from White Sands Missile Range in the summer of 2013.

France, Kevin; Beasley, Matthew; Kane, Robert; Nell, Nicholas; Burgh, Eric B.; Green, James C.

2012-09-01

143

[Design method of convex master gratings for replicating flat-field concave gratings].  

PubMed

Flat-field concave diffraction grating is the key device of a portable grating spectrometer with the advantage of integrating dispersion, focusing and flat-field in a single device. It directly determines the quality of a spectrometer. The most important two performances determining the quality of the spectrometer are spectral image quality and diffraction efficiency. The diffraction efficiency of a grating depends mainly on its groove shape. But it has long been a problem to get a uniform predetermined groove shape across the whole concave grating area, because the incident angle of the ion beam is restricted by the curvature of the concave substrate, and this severely limits the diffraction efficiency and restricts the application of concave gratings. The authors present a two-step method for designing convex gratings, which are made holographically with two exposure point sources placed behind a plano-convex transparent glass substrate, to solve this problem. The convex gratings are intended to be used as the master gratings for making aberration-corrected flat-field concave gratings. To achieve high spectral image quality for the replicated concave gratings, the refraction effect at the planar back surface and the extra optical path lengths through the substrate thickness experienced by the two divergent recording beams are considered during optimization. This two-step method combines the optical-path-length function method and the ZEMAX software to complete the optimization with a high success rate and high efficiency. In the first step, the optical-path-length function method is used without considering the refraction effect to get an approximate optimization result. In the second step, the approximate result of the first step is used as the initial value for ZEMAX to complete the optimization including the refraction effect. An example of design problem was considered. The simulation results of ZEMAX proved that the spectral image quality of a replicated concave grating is comparable with that of a directly recorded concave grating. PMID:19839358

Zhou, Qian; Li, Li-Feng

2009-08-01

144

Spatial heterodyne spectrometer for FLEX  

NASA Astrophysics Data System (ADS)

A spatial heterodyne spectrometer (SHS) has significant advantages for high spectral resolution imaging over narrow pre-selected bands compared to traditional solutions. Given comparable optical étendue at R~6500, a field-widened SHS will have a throughput-resolution product ~170 x larger than an air-spaced etalon spectrometer, and ~1000 x larger than a standard grating spectrometer. The monolithic glass Michelson design and lack of moving parts allows maximum stability of spectral calibration over the mission life. For these reasons, SHS offers considerable advantages for the core spectrometer instrument in the European Space Agency's (ESA) Fluorescence Explorer (FLEX) mission.

Scott, Alan; Zheng, Sheng-Hai; Brown, Stephen; Bell, Andrew

2007-10-01

145

Fiber grating sensors  

Microsoft Academic Search

We review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period-based grating sensors, fiber grating laser-based systems, and interferometric sensor systems based on grating reflectors

Alan D. Kersey; Michael A. Davis; Heather J. Patrick; Michel LeBlanc; K. P. Koo; C. G. Askins; M. A. Putnam; E. Joseph Friebele

1997-01-01

146

Thin substrate grating array for sounding rocket and satellite payloads  

NASA Astrophysics Data System (ADS)

This paper presents critical engineering aspects of a grating array for a sub-orbital rocket payload to make spectral observations in the soft X-ray regime. The off-plane grating mount is a natural solution to maximize throughput and resolution in the 1/4 keV to 1 keV range while minimizing envelope and mass. Replicated radial groove gratings are matched to the convergence angle of the telescope beam to limit aberrations. These lightweight gratings are mounted and aligned in an array which is not only efficient for rocket payloads, but can also be made suitable for the X-ray Grating Spectrometer on Constellation X.

Shipley, Ann; McEntaffer, Randall L.

2008-08-01

147

The Polychromator: A programmable MEMS diffraction grating for synthetic spectra  

SciTech Connect

The authors report here the design, fabrication and demonstration of an electrostatically actuated MEMS diffractive optical device, the Polychromator grating. The Polychromator grating enables a new type of correlation spectrometer for remote detection of a wide range of chemical species, offering electronic programmability, high specificity and sensitivity, fast response and ruggedness. Significant results include: (1) The first demonstrations of user-defined synthetic spectra in the 3-5 {micro}m wavelength regime based upon controlled deflection of individual grating elements in the Polychromator grating; (2) The first demonstration of gas detection by correlation spectroscopy using synthetic spectra generated by the Polychromator grating.

HOCKER,G.B.; YOUNGNER,D.; BUTLER,MICHAEL A.; SINCLAIR,MICHAEL B.; PLOWMAN,THOMAS E.; DEUTSCH,E.; VOLPICELLI,A.; SENTURIA,S.; RICCO,A.J.

2000-04-17

148

Chemical composition of the Orion nebula derived from echelle spectrophotometry  

Microsoft Academic Search

We present echelle spectroscopy in the 3500- to 7060-Å range for two positions of the Orion nebula. The data were obtained using the 2.1-m telescope at Observatorio Astrónmico Nacional in San Pedro Mártir, Baja California. We have measured the intensities of about 220 emission lines, in particular 81 permitted lines of C+, N+, N++, 0°, 0+, Ne0, Si+, Si++ and

C. Esteban; M. Peimbert; S. Torres-Peimbert; V. Escalante

1998-01-01

149

X-ray Diffraction Gratings for Astrophysics  

NASA Astrophysics Data System (ADS)

Over the past year, we have celebrated the tenth anniversary of the Chandra and XMM-Newton X-ray observatories. Both carry powerful, novel diffraction grating spectrometers, which have opened true X-ray spectroscopy for astrophysics. I will describe the design and operation of these instruments, as the background to some of the beautiful results they have produced. But these designs do not exhaust the versatility and essential simplicity of diffraction grating spectrometers, and I will discuss applications for the International X-ray Observatory IXO.

Paerels, Frits

2010-12-01

150

Fabrication of high-energy x-ray transmission gratings for the Advanced X-ray Astrophysics Facility (AXAF)  

Microsoft Academic Search

The High Energy Transmission Grating spectrometer (HETG) on the Advanced X-ray Astrophysics Facility (AXAF) requires the fabrication and assembly of hundreds of large area (approximately equals 6 cm(superscript 2)), low-distortion, ultra-fine-period transmission gratings efficient in the 0.4-10 keV band ((lambda) equals 1.2-30 angstroms). The spectrometer requires two types of gratings: Medium Energy Gratings (MEG), which have a period of 0.4

Mark L. Schattenburg; Richard J. Aucoin; Robert C. Fleming; Irving Plotnik; Jeanne Porter; Henry I. Smith

1994-01-01

151

Super-smooth x-ray reflection grating fabrication  

Microsoft Academic Search

Blazed, grazing incidence x-ray reflection gratings are an important component of modern high resolution spectrometers and related x-ray optics. These have traditionally been fabricated by diamond scribing in a ruling engine, or more recently by interferometric lithography followed by ion etching. These traditional methods result in gratings which suffer from a number of deficiencies, including high surface roughness and poor

A. E. Franke; M. L. Schattenburg; Eric M. Gullikson; J. Cottam; S. M. Kahn; A. Rasmussen

1997-01-01

152

Temporal Dispersion of a Spectrometer  

SciTech Connect

The temporal dispersion of an optical spectrometer has been characterized for a variety of conditions related to optical diagnostics to be fielded at the National Ignition Facility (e.g., Full-Aperture Backscatter Station, Thomson Scattering). Significant time smear is introduced into these systems by the path length difference through the spectrometer. The temporal resolution can be calculated to depend only on the order of the grating, wavelength, and the number of grooves illuminated. To enhance the temporal dispersion, the spectral gratings can be masked limiting the number of grooves illuminated. Experiments have been conducted to verify these calculations. The size and shape of masks are investigated and correlated to the exact shape of the temporal instrument function, which is required when interpreting temporally resolved data. The experiments used a 300fs laser pulse and a picosecond optical streak camera to determine the temporal dispersion. This was done for multiple spectral orders, gratings, and optical masks.

Visco, A; Drake, R P; Froula, D H; Glenzer, S H

2008-05-08

153

Atmospheric chemistry suite (ACS): a set of infrared spectrometers for atmospheric measurements on board ExoMars trace gas orbiter  

NASA Astrophysics Data System (ADS)

The ACS package for ExoMars Trace Gas Orbiter is a part of Russian contribution to ExoMars ESA-Roscosmos mission. On the Orbiter it complements NOMAD investigation and is intended to recover in much extent the science lost with the cancellation of NASA MATMOS and EMCS infrared sounders. ACS includes three separate spectrometers, sharing common mechanical, electrical, and thermal interfaces. NIR is a versatile spectrometer for the spectral range of 0.7-1.6 ?m with resolving power of ~20000. It is conceived on the principle of RUSALKA/ISS or SOIR/Venus Express experiments combining an echelle spectrometer and an AOTF (Acousto-Optical Tuneable Filter) for order selection. Up to 8 diffraction orders, each 10-20 nm wide can be measured in one sequence record. NIR will be operated principally in nadir, but also in solar occultations, and possibly on the limb. MIR is a high-resolution echelle instrument exclusively dedicated to solar occultation measurements in the range of 2.2-4.4 ?m targeting the resolving power of 50000. The order separation is done by means of a steerable grating cross-disperser, allowing instantaneous coverage of up to 300-nm range of the spectrum for one or two records per second. MIR is dedicated to sensitive measurements of trace gases, approaching MATMOS detection thresholds for many species. TIRVIM is a 2- inch double pendulum Fourier-transform spectrometer for the spectral range of 1.7-17 ?m with apodized resolution varying from 0.2 to 1.6 cm-1. TIRVIM is primarily dedicated to monitoring of atmospheric temperature and aerosol state in nadir, and would contribute in solar occultation to detection/reducing of upper limits of some components absorbing beyond 4 ?m, complementing MIR and NOMAD. Additionally, TIRVIM targets the methane mapping in nadir, using separate detector optimized for 3.3-?m range. The concept of the instrument and in more detail the optical design and the expected parameters of its three parts, channel by channel are described.

Korablev, Oleg; Grigoriev, Alexei V.; Trokhimovsky, Alexander; Ivanov, Yurii S.; Moshkin, Boris; Shakun, Alexei; Dziuban, Ilia; Kalinnikov, Yurii K.; Montmessin, Franck

2013-09-01

154

Post-Servicing Mission 4 Flux Calibration of the STIS Echelle Modes  

NASA Astrophysics Data System (ADS)

STIS echelle modes show a wavelength-dependent decline in sensitivity with time. While this trend is observed in all STIS spectroscopic modes, the echelle sensitivity is further affected by a time-dependent shift in the blaze function. To improve the echelle flux calibration, new baselines for the echelle sensitivities are derived from post-Servicing Mission 4 (SM4) observations of the Hubble Space Telescope standard star G191-B2B. We present how these baseline sensitivities compare to pre-failure trends. Specifically, where the new results differ from expectations and discuss anomalous results found in E140H monitoring observations are highlighted.

Azalee Bostroem, K.; Aloisi, A.; Proffitt, C.; Osten, R.; Bohlin, R.

2011-01-01

155

Design and simulation of microspectrometer based on torsional MEMS grating  

NASA Astrophysics Data System (ADS)

Micro-opto-electro-mechanical systems (MOEMS) has prominent advantages over conventional optical devices, such as smaller, lighter, more stable, lower cost and power consumption. It has been widely applied in the last few years. This paper presents a micro spectrometer based on torsional MEMS grating with micromachining process. As a diffractive component in the micro spectrometer, the torsional MEMS grating is actuated by electrostatic force to scan the spectrum. In contrast to common linear detector arrays with stationary diffraction grating and non-fixed grating rotated by stepper motor to scan spectrum used in most micro spectrometer, MEMS-based spectrometer is dynamically controllable, and has no mechanical moving parts with small size. ZEMAX is used for design, optimization, and simulation analysis of the micro spectrometer with multi-configurations in the cross Czerny-Turner optical system. The results indicate that torsional MEMS grating operates at a torsion angle of +/-3 degree, the spectrometer can scan spectral range of 800-1600nm in NIR (near infrared), spectral resolution is around 10 nm, and the whole spectrometer has a volume of 80mm×55mm×30mm. The study provides an initial theoretical foundation for the further development and design.

Yan, Bin; Yuan, Weizheng; Sun, Ruikang; Qiao, Dayong; Yu, Yiting; Li, Taiping

2010-05-01

156

Development of the 2nd Generation Redshift(z) and Early Universe Spectrometer and the Detailed Study of Far-IR Fine-Structure Lines in High-z Galaxies  

NASA Astrophysics Data System (ADS)

The 2nd generation Redshift(z) and Early Universe Spectrometer (ZEUS-2), is a long-slit echelle grating spectrometer ( 1000) for observations at submillimeter wavelengths from 200 to 850 ?m. Its design is optimized for the detection of redshifted far-infrared spectral lines from galaxies in the early universe. Combined with its exquisite sensitivity, broad wavelength coverage, and large 2.5%) instantaneous bandwidth, ZEUS-2 is uniquely suited for studying galaxies between 0.2 and 5—spanning the peaks in both the star formation rate and AGN activity in the universe. ZEUS-2 saw first light at the Caltech Submillimeter Observatory (CSO) in the spring of 2012 and was commissioned on the Atacama Pathfinder Experiment (APEX) this past November. Here we report on the instrument development and performance as well as initial scientific results from the APEX commissioning. We also discuss our ZEUS-1 (the first generation Redshift(z) and Early Universe Spectrometer) detections of the [NII] 122 ?m and [OIII] 88 ?m lines from starburst galaxies at redshifts between ~2.5 and 4. These are the first high-z detections of these lines and they are examples of work we plan to continue with ZEUS-2. As such, they demonstrate the potential of ZEUS-2 for increasing our understanding of galaxies and galaxy evolution over cosmic time.

Ferkinhoff, Carl; Brisbin, D.; Nikola, T.; Parshley, S.; Stacey, G. J.; Hailey-Dunsheath, S. J.; Irwin, K. D.; Cho, H.; Niemack, M.; Benford, D. J.; Staguhn, J.; Phillips, T. G.; Falgarone, E.

2013-01-01

157

V1647 Orionis: Keck/NIRSPEC 2 ?m Echelle Observations  

NASA Astrophysics Data System (ADS)

We present new Keck II NIRSPEC high-spectral resolution 2 ?m echelle observations of the young eruptive variable star V1647 Orionis. This star went into outburst in late 2003 and faded to its pre-outburst brightness after approximately 26 months. V1647 Orionis is the illuminating star of McNeil's Nebula and is located near M 78 in the Lynds 1630 dark cloud. Our spectra have a resolving power of approximately 18,000 and allow us to study in detail the weak absorption features present on the strong near-IR veiled continuum. An analysis of the echelle orders containing Mg I (2.1066 ?m) and Al I (2.1099 ?m), Br? (2.1661 ?m), the Na I doublet (2.206 and 2.209 ?m), and the CO overtone bandhead (2.2935 ?m) gives us considerable information on the physical and geometric characteristics of the regions producing these spectral features. We find that, at high spectral resolution, V1647 Orionis in quiescence resembles a significant number of FU Orionis type eruptive variables and does not appear similar to the quiescent EX Lupi variables observed. This correspondence is discussed and implications for the evolutionary state of the star are considered.

Aspin, Colin; Greene, Thomas P.; Reipurth, Bo

2009-02-01

158

Full image spectral analysis of elemental emissions from an echelle spectrograph  

SciTech Connect

A new algorithm compares the background corrected echelle emission image obtained from reference standards to images of unknowns for quantitative elemental analyses. Wavelength was not used in the calculations but instead pixel position and intensity. The data reduction solution was unique to the particular detector/spectrometer. The approach was found useful for several types of images including ICP, DCP and glow discharge images. The analysis scheme required that the emission pattern of standards and background be held in memory. A dual weighting scheme was used that decreased the importance of pixels in high background areas and enhanced the importance of signals from pixels where the standards had emissions. Threshold values were used to limit the calculations to signals in the linear range of the electronics. Logarithmic weighting, (by taking the square root), was found to work well for weighting pixels from the standards. This assured that minor emissions had some influence on the data fit. In the program the best-fit scalar was determined using simple iterative guess, change and test approaches. The test looked for the minimum least square residual value in the areas of the flagged pixels.

Spencer, W.A.

2000-01-27

159

PEPSI: the Potsdam Echelle Polarimetric and Spectroscopic Instrument for the LBT  

NASA Astrophysics Data System (ADS)

We present the status of PEPSI, the bench-mounted fibre-fed and stabilized "Potsdam Echelle Polarimetric and Spectroscopic Instrument" for the 2×8.4m Large Binocular Telescope in southern Arizona. PEPSI is under construction at AIP and is scheduled for first light in 2009/10. Its ultra-high-resolution mode will deliver an unprecedented spectral resolution of approximately R=310,000 at high efficiency throughout the entire optical/red wavelength range 390-1050nm without the need for adaptive optics. Besides its polarimetric Stokes IQUV mode, the capability to cover the entire optical range in three exposures at resolutions of 40,000, 130,000 and 310,000 will surpass all existing facilities in terms of light-gathering-power times spectral-coverage product. A solar feed will make use of the spectrograph also during day time. As such, we hope that PEPSI will be the most powerful spectrometer of its kind for the years to come.

Strassmeier, K. G.; Woche, M.; Ilyin, I.; Popow, E.; Bauer, S.-M.; Dionies, F.; Fechner, T.; Weber, M.; Hofmann, A.; Storm, J.; Materne, R.; Bittner, W.; Bartus, J.; Granzer, T.; Denker, C.; Carroll, T.; Kopf, M.; DiVarano, I.; Beckert, E.; Lesser, M.

2008-08-01

160

ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations  

Microsoft Academic Search

ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will combine the efficiency of modern echelle spectrograph design with extreme radial-velocity precision. It will be installed on ESO's VLT in order to achieve a gain of two magnitudes with respect to its predecessor HARPS, and the instrumental radialvelocity precision will be improved to reach cm\\/s level. Thanks to

Francesco A. Pepe; Stefano Cristiani; Rafael Rebolo Lopez; Nuno C. Santos; Antonio Amorim; Gerardo Avila; Willy Benz; Piercarlo Bonifacio; Alexandre Cabral; Pedro Carvas; Roberto Cirami; João Coelho; Maurizio Comari; Igor Coretti; Vincenzo de Caprio; Hans Dekker; Bernard Delabre; Paolo di Marcantonio; Valentina D'Odorico; Michel Fleury; Ramón García; José Miguel Herreros Linares; Ian Hughes; Olaf Iwert; Jorge Lima; Jean-Louis Lizon; Gaspare Lo Curto; Christophe Lovis; Antonio Manescau; Carlos Martins; Denis Mégevand; André Moitinho; Paolo Molaro; Mario Monteiro; Manuel Monteiro; Luca Pasquini; Christoph Mordasini; Didier Queloz; José L. Rasilla; José M. Rebordão; Samuel Santana Tschudi; Paolo Santin; Danuta Sosnowska; Paolo Spanò; Fabio Tenegi; Stéphane Udry; Eros Vanzella; Matteo Viel; Maria Rosa Zapatero Osorio; Filippo Zerbi

2010-01-01

161

Fabrication of low straylight holographic gratings for space applications  

NASA Astrophysics Data System (ADS)

The main challenges of fabricating diffraction gratings for use in earth monitoring spectrometers are given by the requirements for low stray light, high diffraction efficiency and a low polarization sensitivity. Furthermore the use in space also requires a high environmental stability of these gratings. We found that holography in combination with ion beam plasma etching provides a way to obtain monolithic, robust fused silica gratings which are able to meet the above mentioned requirements for space applications. Holography accompanied by plasma etching allows the fabrication of a wide range of different grating profiles to optimize the efficiency including the polarization behavior according to a wealth of applications. Typical profile shapes feasible are blazed gratings, sinusoidal profiles and binary profiles and this allows to tailor the efficiency and polarization requirements exactly to the spectral range of the special application. Holographic gratings can be fabricated on plane and also on curved substrates as core components of imaging spectrometers. In this paper we present our grating fabrication flow for the example of plane blazed gratings and we relate the efficiency and stray light measurement results to certain steps of the process. The holographic setup was optimized to minimize stray light and ghosting recorded by the photoresist during the exposure. Low wave front deviations require the use of highly accurate grating substrates and high precision optics in the holographic exposure.

Steiner, Reinhard; Pesch, Alexander; Erdmann, Lars H.; Burkhardt, Matthias; Gatto, Alexandre; Wipf, Robert; Diehl, Torsten; Vink, H. J. P.; van den Bosch, B. G.

2013-09-01

162

Critical-angle Transmission Grating Development for AXSIO  

NASA Astrophysics Data System (ADS)

Large area, high resolving power spectroscopy in the soft x-ray band can at present only be achieved with a state-of-the-art diffraction grating spectrometer. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Several new mission concepts containing CAT grating based spectrometers such as AXSIO promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit. The CAT grating principle has previously been demonstrated with x rays using small wet-etched samples. We report the latest progress in the fabrication and testing of large (32x32 mm2) CAT grating prototypes with an integrated hierarchy of low-obstruction support structures. The gratings are fabricated from silicon-on-insulator wafers using advanced lithography and highly anisotropic dry and wet etching techniques. We present our latest grating fabrication results.

Bautz, Mark W.; Heilmann, R. K.; Schattenburg, M.; Marshall, H. L.; Huenemoerder, D.; Dewey, D.; Schulz, N. S.; Davis, J. E.

2013-04-01

163

Critical-Angle Transmission Grating Development for AXSIO  

NASA Astrophysics Data System (ADS)

Large area, high resolving power spectroscopy in the soft x-ray band can only be achieved with a state-of-the-art diffraction grating spectrometer. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Since the demise of IXO there are no soft x-ray spectroscopy missions in the pipeline, but several new mission concepts containing CAT grating based spectrometers such as AXSIO promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit. The CAT grating principle has previously been demonstrated with x rays using small wet-etched samples. We report the latest progress in the fabrication and testing of large (32x32 mm^2) CAT grating prototypes with an integrated hierarchy of low-obstruction support structures. The gratings are fabricated from silicon-on-insulator wafers using advanced lithography and highly anisotropic dry and wet etching techniques. We present our latest grating fabrication results.

Heilmann, Ralf K.; Bruccoleri, A.; Mukherjee, P.; Schattenburg, M. L.; Bautz, M. W.; Huenemoerder, D.; Davis, J. E.; Dewey, D.; Marshall, H. L.; Schulz, N. S.

2013-01-01

164

Fiber grating spectra  

Microsoft Academic Search

In this paper, we describe the spectral characteristics that can be achieved in fiber reflection (Bragg) and transmission gratings. Both principles for understanding and tools for designing fiber gratings are emphasized. Examples are given to illustrate the wide variety of optical properties that are possible in fiber gratings. The types of gratings considered include uniform, apodized, chirped, discrete phase-shifted, and

T. Erdogan

1997-01-01

165

Optimum design of a holographic parallel flat-field grating  

NASA Astrophysics Data System (ADS)

To widen the working waveband, a new holographic parallel flat-field grating (HPFG) with two sub-gratings lying parallel on the same substrate is designed. Grating parameters of the two gratings, one for 2~5 nm and the other for 5~30 nm, are optimized based on the aberration theory of concave grating. The radius tolerances of curvature of the substrate are also analyzed. Ray-traced spectral images indicate that errors cased by ±1% deviation of radius can be offset by shifting the detector position within 2.5 mm. Finally, we analyze the spectral image-focusing properties. Theoretical spectral resolution of this new HPFG is pretty much the same as that of existing holographic flat-field grating. The simulation results demonstrate that our work probably can be used in the compact spectrometers with a broad spectral region and moderately high resolution.

Wang, Qing-bo; Liu, Zheng-kun; Chen, Huo-yao; Fu, Shao-jun

2013-08-01

166

Materials and fabrication issues for large machined germanium immersion gratings  

NASA Astrophysics Data System (ADS)

LLNL has successfully fabricated small (1.5 cm2 area) germanium immersion gratings. We studied the feasibility of producing a large germanium immersion grating by means of single point diamond flycutting. Our baseline design is a 63.4° blaze echelle with a 6 cm beam diameter. Birefringence and refractive index inhomogeneity due to stresses produced by the crystal growth process are of concern. Careful selection of the grating blank and possibly additional annealing to relieve stress will be required. The Large Optics Diamond Turning Machine (LODTM) at LLNL is a good choice for the fabrication. It can handle parts up to 1.5 meter in diameter and 0.5 meter in length and is capable of a surface figure accuracy of better than 28 nm rms. We will describe the machine modifications and the machining process for a large grating. A next generation machine, the Precision Optical Grinder and Lathe (POGAL), currently under development has tighter specifications and could produce large gratings with higher precision.

Kuzmenko, Paul J.; Davis, Pete J.; Little, Steve L.; Hale, Layton C.

2006-07-01

167

The Echelon-cross-Echelle Spectrograph for SOFIA  

NASA Astrophysics Data System (ADS)

The Echelon-cross-Echelle Spectrograph (EXES), one of the first generation instruments for the Statospheric Observatory for Infrared Astronomy (SOFIA) will provide a unique tool for examining the ISM and star formation. The EXES high spectral resolution mode, R ? 120 000 from 4.5 ?m to 28.3 ?m, is designed for line observations of gas-phase molecules. The improved atmospheric transmission guaranteed by SOFIA will make observations of molecules such as H2O and CH4 fairly routine. EXES will also have medium and low resolution modes to enable a wide range of science projects. EXES is a PI instrument open for collaborative proposals following the model of the successful TEXES instrument (Lacy et al. 2002). It is currently scheduled for first science flights on SOFIA in 2013.

Richter, M. J.; Seifahrt, A.; McKelvey, M.; Zell, P.

2011-11-01

168

Development of Multiple-Element Flame Emission Spectrometer Using CCD Detection  

ERIC Educational Resources Information Center

|The full wavelength coverage of charge coupled device (CCD) detector when coupled with an echelle spectrography, the system allows for simultaneously multiple element spectroscopy to be performed. The multiple-element flame spectrometer was built and characterized through the analysis of environmentally significant elements such as Ca, K, Na, Cu,…

Seney, Caryn S.; Sinclair, Karen V.; Bright, Robin M.; Momoh, Paul O.; Bozeman, Amelia D.

2005-01-01

169

Surface Plasmon Based Spectrometer  

NASA Astrophysics Data System (ADS)

A spectrometer that uses surface plasmon excitation in thin metal films to separate light into its component wavelengths is described. The use of surface plasmons as a dispersive medium sets this spectrometer apart from prism, grating, and interference based variants and allows for the miniaturization of this device. Theoretical and experimental results are presented for two different operation models. In the first case surface plasmon tunneling in the near field is used to provide transmission spectra of different broad band-pass, glass filters across the visible wavelength range with high stray-light rejection at low resolution as well as absorption spectra of chlorophyll extracted from a spinach leaf. The second model looks at the far field components of surface plasmon scattering.

Wig, Andrew; Passian, Ali; Boudreaux, Philip; Ferrell, Tom

2008-03-01

170

Varied line-space gratings: past, present and future  

SciTech Connect

A classically ruled diffraction grating consists of grooves which are equidistant, straight and parallel. Conversely, the so-called ''holographic'' grating (formed by the interfering waves of coherent visible light), although severely constrained by the recording wavelength and recording geometry, has grooves which are typically neither equidistant, straight nor parallel. In contrast, a varied line-space (VLS) grating, in common nomenclature, is a design in which the groove positions are relatively unconstrained yet possess sufficient symmetry to permit mechanical ruling. Such seemingly exotic gratings are no longer only a theoretical curiosity, but have been ruled and used in a wide variety of applications. These include: (1) aberration-corrected normal incidence concave gratings for Seya-Namioka monochromators and optical de-multiplexers, (2) flat-field grazing incidence concave gratings for plasma diagnostics, (3) aberration-corrected grazing incidence plane gratings for space-borne spectrometers, (4) focusing grazing incidence plane grating for synchrotron radiation monochromators, and (5) wavefront generators for visible interferometry of optical surfaces (particularly aspheres). Future prospects of VLS gratings as dispersing elements, wavefront correctors and beamsplitters appear promising. The author discusses the history of VLS gratings, their present applications, and their potential in the future. 61 refs., 24 figs.

Hettrick, M.C.

1985-08-01

171

High-throughput accurate-wavelength lens-based visible spectrometer  

NASA Astrophysics Data System (ADS)

A scanning visible spectrometer has been prototyped to complement fixed-wavelength transmission grating spectrometers for charge exchange recombination spectroscopy. Fast f/1.8 200 mm commercial lenses are used with a large 2160 mm-1 grating for high throughput. A stepping-motor controlled sine drive positions the grating, which is mounted on a precision rotary table. A high-resolution optical encoder on the grating stage allows the grating angle to be measured with an absolute accuracy of 0.075 arc sec, corresponding to a wavelength error <=0.005 A?. At this precision, changes in grating groove density due to thermal expansion and variations in the refractive index of air are important. An automated calibration procedure determines all the relevant spectrometer parameters to high accuracy. Changes in bulk grating temperature, atmospheric temperature, and pressure are monitored between the time of calibration and the time of measurement to ensure a persistent wavelength calibration.

Bell, Ronald E.; Scotti, Filippo

2010-10-01

172

Novel immersion grating, VPH grating, and quasi-Bragg grating  

NASA Astrophysics Data System (ADS)

We have successfully fabricated germanium immersion gratings with resolving power of 45,000 at 10 ?m by using a nano precision 3D grinding machine and ELID (ELectrolytic In-process Dressing) method. However the method spends large amount of machine times. We propose grooves shape with a new principle for a solid grating, which achieves high performance and lower cost. We have developed volume phase holographic (VPH) grisms with zinc selenide (ZnSe) prisms for spectrograph of the Subaru Telescope and the other telescopes. While a VPH grism with high index prisms achieves higher dispersion, diffraction efficiency of VPH grating decreases toward higher orders. A "quasi-Bragg grating" which inherits advantage of a VPH grating achieves high diffraction efficiency toward higher orders. Wavelength tuners with a pair of counter-rotation prisms for a VPH and quasi-Bragg grating obtain high diffraction efficiency over wide wavelength range. The novel immersion grating, VPH grism with high index prisms, quasi-Bragg grating and wavelength tuners dramatically reduce volumes of astronomical spectrographs.

Ebizuka, Noboru; Oka, Keiko; Yamada, Akiko; Kashiwagi, Masako; Kodate, Kashiko; Kawabata, Koji S.; Uehara, Mariko; Nagashima, Chie; Ichiyama, Kotaro; Ichikawa, Takashi; Shimizu, Tomoyuki; Morita, Shinya; Yamagata, Yutaka; Omori, Hitoshi; Tokoro, Hitoshi; Hirahara, Yasuhiro; Sato, Shuji; Iye, Masanori

2006-07-01

173

Photoacoustic spectrometer for ozone detection  

NASA Astrophysics Data System (ADS)

A high-resolution external laser photoacoustic spectrometer has been developed. The spectrometer was used to analyze the absorption transitions of the ozone in coincidence with the CO2 laser emission and to evaluate its limit of sensitivity. A CO2 laser and a photoacoustic resonant cell, totally built in project, formed the spectrometer. The CO2 laser operates in 80 CW transitions distributed in the regular bands with power of up to 15W, tuned by a diffraction grating. The cell has frequency resonance of longitudinal mode close to 1600 Hz. The cell is equipped with two small electret microphones and ZnSe windows in Brewster angle. The quality factor of the cell was measured about 30 through the ozone absorption in resonance with the 9P14 line of CO2 laser. The spectrometer sensitivity limit was preliminary evaluated for ozone detection around 100 ppb.

Telles, Edjar M.; Bezerra, Edson; Scalabrin, Artemio

2001-08-01

174

The GMT-CfA, Carnegie, Catolica, Chicago Large Earth Finder (G-CLEF): a general purpose optical echelle spectrograph for the GMT with precision radial velocity capability  

NASA Astrophysics Data System (ADS)

The GMT-CfA, Carnegie, Catolica, Chicago Large Earth Finder (G-CLEF) is a fiber fed, optical echelle spectrograph that has undergone conceptual design for consideration as a first light instrument at the Giant Magellan Telescope. GCLEF has been designed to be a general-purpose echelle spectrograph with precision radial velocity (PRV) capability. We have defined the performance envelope of G-CLEF to address several of the highest science priorities in the Decadal Survey1. The spectrograph optical design is an asymmetric, two-arm, white pupil design. The asymmetric white pupil design is adopted to minimize the size of the refractive camera lenses. The spectrograph beam is nominally 300 mm, reduced to 200 mm after dispersion by the R4 echelle grating. The peak efficiency of the spectrograph is >35% and the passband is 3500-9500Å. The spectrograph is primarily fed with three sets of fibers to enable three observing modes: High-Throughput, Precision-Abundance and PRV. The respective resolving powers of these modes are R~ 25,000, 40,000 and 120,000. We also anticipate having an R~40,000 Multi-object Spectroscopy mode with a multiplex of ~40 fibers. In PRV mode, each of the seven 8.4m GMT primary mirror sub-apertures feeds an individual fiber, which is scrambled after pupil-slicing. The goal radial velocity precision of G-CLEF is ?V <10 cm/sec radial. In this paper, we provide a flowdown from fiducial science programs to design parameters. We discuss the optomechanical, electrical, structural and thermal design and present a roadmap to first light at the GMT.

Szentgyorgyi, A.; Frebel, A.; Furesz, G.; Hertz, E.; Norton, T.; Bean, J.; Bergner, H.; Crane, J.; Evans, J.; Evans, I.; Gauron, T.; Jordán, A.; Park, S.; Uomoto, A.; Barnes, S.; Davis, W.; Eisenhower, M.; Epps, H.; Guzman, D.; McCracken, K.; Ordway, M.; Plummer, D.; Podgorski, W.; Weaver, D.

2012-09-01

175

Dual band hyperspectral imaging spectrometer  

Microsoft Academic Search

A temporally and spatially non-scanning imaging spectrometer covering two separate spectral bands in the visible region using computed tomographic imaging techniques is described. The computed tomographic techniques allow for the construction of a three-dimensional hyperspectral data cube (x, y, lambda) from the two-dimensional input in a single frame time. A computer generated holographic dispersive grating is used to disperse the

John Paul Hartke

2005-01-01

176

Bragg Grating Simulation Software.  

National Technical Information Service (NTIS)

This document is a user manual for a software application that predicts the complex reflection spectrum of fibre Bragg gratings, given user defined input parameters. The software is designed primarily to complement the joint DSTO/ Swinburne grating writin...

C. Brooks C. Davis

2008-01-01

177

Interaction between luminance gratings and disparity gratings  

Microsoft Academic Search

It was shown from geometry and photographic measurement that the shading pattern for a sinusoidal corrugated surface of frequency f approximates to a luminance-deé ned grating of frequency f, 2f or f C 2f in specié c relative phase. It was coné rmed that a luminance grating modié es the appearance of a suprathreshold stereoscopic corrugated surface, suggesting an interaction

Michael Wright; Tim Ledgeway

2004-01-01

178

Analysis of nonuniform gratings  

Microsoft Academic Search

It has been shown earlier that the launching of gap solitons into nonuniform nonlinear Bragg gratings can be significantly easier than for uniform nonlinear Bragg gratings. In this paper we examine a variety of simple nonuniform Bragg gratings and compare their suitability for the launching process, by studying the positions of the zeros of the reflection spectrum.

Neil G. R. Broderick; C. Martijn de Sterke

1995-01-01

179

Catwalk grate lifting tool  

DOEpatents

A device is described for lifting catwalk grates comprising an elongated bent member with a handle at one end and a pair of notched braces and a hook at the opposite end that act in conjunction with each other to lock onto the grate and give mechanical advantage in lifting the grate. 10 figs.

Gunter, L.W.

1992-08-11

180

Transmission Grating Measurements of Undulator K  

SciTech Connect

This study was undertaken to understand the practicalities of determine K differences in the undulator modules by measuring single-shot x-ray spectra of the spontaneous radiation with a transmissive grating spectrometer under development to measure FEL spectra. Since the quality of the FEL is dependent on a uniform K value in all the undulator modules, being able to measure the relative undulator K values is important. Preliminary results were presented in a presentation, 'Use of FEL Off-Axis Zone Plate Spectrometer to Measure Relative K by the Pinhole/Centroid Method', at the 'LCLS Beam-Based Undulator K Measurements Workshop' on November 14, 2005 (UCRL-PRES-217281). This study applies equally well to reflective gratings of the appropriate period and inclinations.

Bionta, R. M.

2010-12-01

181

First science observations with the ACES echelle spectrograph  

NASA Astrophysics Data System (ADS)

The use of spectrographs with telescopes having high order adaptive optics (AO) systems offers the possibility of achieving near diffraction-limited spectral resolution with ground-based telescopes, as well as important advantages for instrument design. The use of an optical fiber to couple the instrument to the telescope affords additional advantages such as flexibility in the placement of the instrument and improved homogeneity of the input illumination function. In the case of Steward Observatory's Adaptively Coupled Echelle Spectrograph (ACES), the instrument is normally coupled to the telescope with an 8 micron diameter near single-mode optical fiber, although the instrument can be used at fixed focus locations without the fiber for telescopes so equipped. The use of a fiber coupler results in the phenomenon known as 'modal noise', where the transmission of multiple modes in the fiber leads to a wavelength-dependent variation in illumination that limits flat fielding precision. We have largely eliminated this effect through the use of an automated fiber stretcher device. We report here on improvements to the fiber feed optics and on interim observations made with the instrument at a conventional telescope not equipped with adaptive optics.

Reynolds, Robert O.; Lloyd-Hart, Michael

2004-09-01

182

AVES: an adaptive optics visual echelle spectrograph for the VLT  

NASA Astrophysics Data System (ADS)

We present the preliminary study of a low cost, high performance spectrograph for the VLT, for observations in the V, R and I bands. This spectrograph is meant for intermediate (R equals 16,000) resolution spectroscopy of faint (sky and/or detector limited) sources, with particular emphasis on the study of solar-type (F-G) stars belonging to the nearest galaxies and to distant (or highly reddened) galactic clusters. The spectrograph is designed to use the adaptive optics (AO) systems at the VLT Telescope. Even if these AO systems will not provide diffraction limited images in the V, R and I bands, the photon concentration will still be above approximately 60% of the flux in an 0.3 arcsecond aperture for typical Paranal conditions. This makes the construction of a compact, cheap and efficient echelle spectrograph possible. AVES will outperform comparable non adaptive optic instruments by more than one magnitude for sky- and/or detector-limited observations, and it will be very suitable for observations in crowded fields.

Pasquini, Luca; Delabre, Bernard; Avila, Gerardo; Bonaccini, Domenico

1998-07-01

183

A new stellar spectrometer based on a linear CCD array  

Microsoft Academic Search

A spectrometer for measuring the energy distribution in stellar spectra in the wavelength range from 0.4 to 1.0 micron is presented. Spectra are registered by means of a linear CCD array. The optical scheme with cross dispersion is applied in the spectrometer, which makes it possible to observe a stellar spectrum in two orders of grating: the first order has

A. G. Zuev; G. V. Kir'ian; V. S. Korepanov; M. I. Rybakov; N. A. Sokolov

1991-01-01

184

Design And Operation of the Pioneer Venus Orbiter Ultraviolet Spectrometer  

Microsoft Academic Search

The University of Colorado's Ultraviolet Spectrometer instrument carried on the Pioneer Venus Orbiter spacecraft is a 125 mm f\\/5 Ebert-Fastie design with a 250-mm Cassegrainian telescope. The instrument has extensive logic to control the grating motor drive and to adapt the basic spectrometer to the constraints and opportunities of the mission. Success has been achieved in reconciling the confficting requirements

A. I. F. Stewart

1980-01-01

185

Performance of volume phase holographic transmission grating recorded in DCG for PGP  

Microsoft Academic Search

The volume phase holographic (VPH) transmission grating recorded in dichromate gelatin (DCG) with a specific spectral coverage from 420 nm to 760 nm is designed for a novel prism-grating-prism imaging spectrometer. Based on the Rigorous Coupled-Wave Analysis, its performances are predicted and analyzed. The grating is manufactured and its properties are measured experimentally. The diffraction efficiency over the spectral range,

Ming Li; Minxue Tang; Haohan Xia; Chunhuan Fang; Jianhong Wu; Xunjie Zhao

2010-01-01

186

Slow-light enhanced spectrometers on chip  

NASA Astrophysics Data System (ADS)

We propose using slow light structures to greatly enhance the spectral performance of on-chip spectrometers. We design a calzone photonic crystal line-defect waveguide which can have large group index over a certain wavelength range. An arrayed waveguide gratings (AWGs) is studied as an example, and the performance of such a slow-light AWG is analyzed numerically.

Shi, Zhimin; Boyd, Robert W.

2011-06-01

187

Correlation spectrometer  

DOEpatents

A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

Sinclair, Michael B. (Albuquerque, NM); Pfeifer, Kent B. (Los Lunas, NM); Flemming, Jeb H. (Albuquerque, NM); Jones, Gary D. (Tijeras, NM); Tigges, Chris P. (Albuquerque, NM)

2010-04-13

188

CD Spectrometer  

NSDL National Science Digital Library

In this activity, learners use a compact disc to make a spectrometer, an instrument used to measure properties of light. Learners use their spectrometer to view a continuous spectrum produced by fluorescent light. This lesson guide also includes instructions on how to build a spectroscope from a cereal box.

Doherty, Paul

2000-01-01

189

The Constellation-X RGS options: raytrace modeling of the off-plane gratings  

NASA Astrophysics Data System (ADS)

The Reflection Grating Spectrometer of the Constellation-X mission has two strong candidate configurations. The first configuration, the in-plane grating (IPG), is a set of reflection gratings similar to those flown on XMM-Newton and has grooves perpendicular to the direction of incident light. In the second configuration, the off-plane grating (OPG), the grooves are closer to being parallel to the incident light, and diffract along a cone. It has advantages of higher packing density, and higher reflectivity. Confinement of these gratings to sub-apertures of the optic allow high spectral resolution. We have developed a raytrace model and analysis technique for the off-plane grating configuration. Initial estimates indicate that first order resolving powers in excess of 1000 (defined with half-energy width) are achievable for sufficiently long wavelengths (? >= 12Å), provided separate accommodation is made for gratings in the subaperture region farther from the zeroth order location.

Flanagan, Kathryn A.; Davis, John E.; Heilmann, Ralf K.; Levine, Alan M.; McGuirk, Michael; Ricker, George R.; Schattenburg, Mark L.; Wise, Michael; Rasmussen, Andrew; Bookbinder, Jay A.; Freeman, Mark D.; Gaetz, Terrance J.; Jerius, Diab; Nguyen, Dan; Podgorski, William A.; Reid, P. B.; Cash, Webster C.; Shipley, Ann F.; Gallagher, Dennis J.; Huang, Pei; Jordan, Steve P.

2004-10-01

190

The design and simulation of single detector MIR spectrometer based on MEMS scanning mirror  

Microsoft Academic Search

Infrared (IR) spectrometers are very important optical equipments that can be used in industry, science, medicine, agriculture, biology and food safety etc., and the market is growing. However, most traditional IR spectrometers, such as Fourier transform spectrometer (FTS) that based on Michelson interferometer principle and scanning monochromator that based on grating scanning, are expensive, relative large volume, and stationary, which

Zhong-Wei Zhang; Zhi-Yu Wen; Tian-Ling Zeng; Kang-Lin Wei

2011-01-01

191

Galileo Ultraviolet Spectrometer experiment  

NASA Astrophysics Data System (ADS)

The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113-432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg x 0.1 deg for illuminated disk observations and 1 deg x 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg x 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170-432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.

Hord, C. W.; McClintock, W. E.; Stewart, A. I. F.; Barth, C. A.; Esposito, L. W.; Thomas, G. E.; Sandel, B. R.; Hunten, D. M.; Broadfoot, A. L.; Shemansky, D. E.

1992-05-01

192

Cascaded interferometric imaging spectrometer  

NASA Astrophysics Data System (ADS)

We present what we believe to be a novel method for order sorting a Fabry-Perot interferometer using a Fourier transform spectrometer (FTS) in tandem. We demonstrate how the order sorting is achieved using a model instrument response as an example of an instrument working in the 5-25 ?m band, although the method is generally applicable at all wavelengths. We show that an instrument of this type can be realized with a large bandwidth, a large field of view, and good transmission efficiency. These attributes make this instrument concept a useful technique in applications where true imaging spectroscopy is required, such as mapping large astronomical sources. We compare the performance of the new instrument to grating and standard FTS instruments in circumstances where the measurement is background and detector noise limited. We use a figure of merit based on the field of view and speed of detection and find that the new system has a speed advantage over a FTS with the same field of view in all circumstances. The instrument will be faster than a grating instrument with the same spectral resolution once the field of view is >13 times larger under high background conditions and >50 times larger with detector performances that match the photon noise from Zodiacal light.

Swinyard, Bruce; Ferlet, Marc

2007-09-01

193

Cascaded interferometric imaging spectrometer.  

PubMed

We present what we believe to be a novel method for order sorting a Fabry-Perot interferometer using a Fourier transform spectrometer (FTS) in tandem. We demonstrate how the order sorting is achieved using a model instrument response as an example of an instrument working in the 5-25 microm band, although the method is generally applicable at all wavelengths. We show that an instrument of this type can be realized with a large bandwidth, a large field of view, and good transmission efficiency. These attributes make this instrument concept a useful technique in applications where true imaging spectroscopy is required, such as mapping large astronomical sources. We compare the performance of the new instrument to grating and standard FTS instruments in circumstances where the measurement is background and detector noise limited. We use a figure of merit based on the field of view and speed of detection and find that the new system has a speed advantage over a FTS with the same field of view in all circumstances. The instrument will be faster than a grating instrument with the same spectral resolution once the field of view is >13 times larger under high background conditions and >50 times larger with detector performances that match the photon noise from Zodiacal light. PMID:17805378

Swinyard, Bruce; Ferlet, Marc

2007-09-01

194

Performance characterization of the reflection grating arrays (RGA) for the RGS experiment aboard XMM  

NASA Astrophysics Data System (ADS)

The Reflection Grating Spectrometer (RGS) aboard XMM is a large collecting area, dispersive soft x-ray spectrometer providing high resolution and a bandpass of 5-35 angstrom. We have built and characterized the two, nearly identical, flight model reflection grating arrays for the RGS instrument. Precision alignment and assembly of 182 grating elements into each array was performed at Columbia Astrophysics/Nevis Laboratory, and end-to-end X-ray calibration and testing were performed at the MPE-Panter facility. Preliminary results from the calibration are summarized, and reconciliation of those results with baseline optical design, simulations and error budgets are discussed.

Rasmussen, Andrew; Cottam, Jean; Decker, Todd A.; Kahn, Steven M.; Spodek, Joshua; Stern, M.; Erd, Christian; den Boggende, Antonius J.; Brinkman, Albert C.; den Herder, Jan-Willem; Paerels, Frits B.; Vries, C. D.

1998-11-01

195

An imaging spectrometer for astronomy  

NASA Astrophysics Data System (ADS)

An imaging spectrometer is described that can analyze all of the elements of astronomical images by means of a multilens array that isolates contiguous points of the image. The 'integral field' device is based on the use of a Fabry-Perot in cross dispersion with a grating yielding high resolution for a large spectral grating range. The device also employs techniques based on the principle of channeled spectra and the use of an insect-eye lens in conjunction with an interferometer. The spectra are arranged in different inclined rows to optimize coverage, and 400 spectra can be obtained with a 2000 x 2000-pixel receptor during 40-channel screening with a resolution of about 30,000 and a 200 nm range. The device is shown to have the same Doppler shift for each Fabry-Perot scanning step and a high number of channeled elements, which makes the device suitable for measuring radial velocities by means of correlation techniques.

Le Coarer, Etienne; Georgelin, Yvon; Monnet, Guy

1992-07-01

196

SCINTILLATION SPECTROMETER  

DOEpatents

A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitting substances in tissue. The spectrometer includes a collimator having a plurality of apertures that are hexagonal in cross section. Two crystals are provided: one is activated to respond to incident rays from the collimator; the other is not activated and shields the first from external radiation.

Bell, P.R.; Francis, J.E.

1960-06-21

197

Dual waveband compact catadioptric imaging spectrometer  

SciTech Connect

A catadioptric dual waveband imaging spectrometer that covers the visible through short-wave infrared, and the midwave infrared spectral regions, dispersing the visible through shortwave infrared with a zinc selenide grating and midwave infrared with a sapphire prism. The grating and prism are at the cold stop position, enabling the pupil to be split between them. The spectra for both wavebands are focused onto the relevant sections of a single dual waveband detector. Spatial keystone distortion is controlled to less than one tenth of a pixel over the full wavelength range, facilitating the matching of the spectra in the midwave infrared with the shorter wavelength region.

Chrisp, Michael P.

2012-12-25

198

Overall Philosophy of the Echelle Spectrographs for the Anglo Australian Telescope and William Herschel Telescope  

Microsoft Academic Search

Two large echelle spectrographs are under construction which will provide essentially identical spectra at observatories in the northern and southern hemisphere. Observers will see the same software for instrument control and data reduction at both observatories, and on the UK STARLINK network. This paper considers how such an instrument fits whithin the overall system, and draws conclusions which are relevant

D. D. Walker

1988-01-01

199

Image quality with array spectrometers  

NASA Astrophysics Data System (ADS)

We present data on the image quality achieved with the near IR array spectrometer cooled grating spectrometer 4 (CGS4) on the UK IR telescope (UKIRT) on Mauna Kea. A design spot size of 30 micrometers was specified for CGS4, to maintain acceptable image quality with both the 58 by 62 pixel array with which it is currently equipped and the 256 by 256 array which CGS4 was also designed to accommodate. Details are given of the design, construction and alignment method which allow linear tolerances of 50 micrometers and angular tolerances of 25 mrad to be met and maintained at cryogenic temperatures. The instrumental flexure is also discussed. Both laboratory spectra and those taken at the telescope illustrate that design spot sizes of 30 micrometers have been achieved in the near IR. It will be demonstrated that the theoretical resolution of the instrument is attained for resolving powers from approximately 200 to 20,000.

Ramsay Howat, Suzanne K.; Wright, Gillian S.; Mountain, C. Matt; Montgomery, David; Atad-Ettedgui, Eli I.

1994-06-01

200

New family of reflective spectrometers  

NASA Astrophysics Data System (ADS)

Three kinds of spectrometers based on off-axis Schmidt and Schmidt-Cassegrain cameras are presented; they have been used for several instruments studies, mainly for European Space Agency and Agenzia Spaziale Italiana. Both dispersive prism and grating based configurations have interesting characteristics, such as: simplicity, low cost, high efficiency, small volume and weight, very low sensitivity to polarization and great flexibility also in multichannel (wavebands) configurations. The image quality is high, even with low relative apertures and great fields of view, allowing a very good correction of smile and keystone. The compensation of the slit curvature induced by a prism disperser is also demonstrated. This family of spectrometers was the topic of three patents, belonging to Selex-Galileo, while the intellectual property belongs to A. Romali et al.

Romoli, Andrea; Simonetti, Francesca; Gambicorti, Lisa; Marchi, Alessandro Zuccaro

2011-01-01

201

XMM (X-ray Multi-Mirror Mission) space telescope: Development plan for the lightweight replicated x-ray gratings  

Microsoft Academic Search

An approach and development plan for the production of replicated variable line spacing x-ray reflection gratings on lightweight substrates is described. The gratings will be arrayed in spectrometers to analyze the soft x-rays gathered by the telescopes flown around the European Space Agency (ESA) X-ray Multi-Mirror Mission'' (XMM). The mission requires about 750 gratings to form 3 arrays. Each array

R. C. Montesanti; D. P. Atkinson; D. F. Edwards; J. L. Klingmann

1990-01-01

202

Off-plane grazing incidence Constellation-X grating calibrations using polarized synchrotron radiation and PCGRATE code calculations  

Microsoft Academic Search

Efficiency measurements of a grazing-incidence diffraction grating, planned for the Constellation-X Reflection Grating Spectrometer (RGS), were performed using polarized synchrotron radiation at the NRL Brookhaven beamline X24C. The off-plane TM and TE efficiencies of the 5000 groove\\/mm MIT test grating, patterned on a silicon wafer, were measured and compared to the efficiencies calculated using the PCGRATE-SX code. The calculated and

J. F. Seely; L. I. Goray; Benjawan Kjornrattanawanich; J. M. Laming; G. E. Holland; K. A. Flanagan; R. K. Heilmann; C.-H. Chang; M. L. Schattenburg; A. P. Rasmussen

2005-01-01

203

Off-Plane Grazing Incidence Constellation-X Grating Calibrations using Polarized Synchrotron Radiation and PCGRATE Code Calculations  

Microsoft Academic Search

Efficiency measurements of a grazing-incidence diffraction grating, planned for the Constellation-X Reflection Grating Spectrometer (RGS), were performed using polarized synchrotron radiation at the NRL Brookhaven beamline X24C. The off-plane TM and TE efficiencies of the 5000 groove\\/mm MIT test grating, patterned on a silicon wafer, were measured and compared to the efficiencies calculated using the PCGRATE-SX code. The calculated and

J. F. Seely; L. I. Goray; Benjawan Kjornrattanawanich; J. M. Laming; G. E. Holland; K. A. Flanagan; R. K. Heilmann; C.-H. Chang; M. L. Schattenburg; A. P. Rasmussenf

204

Performance of volume phase holographic transmission grating recorded in DCG for PGP  

NASA Astrophysics Data System (ADS)

The volume phase holographic (VPH) transmission grating recorded in dichromate gelatin (DCG) with a specific spectral coverage from 420 nm to 760 nm is designed for a novel prism-grating-prism imaging spectrometer. Based on the Rigorous Coupled-Wave Analysis, its performances are predicted and analyzed. The grating is manufactured and its properties are measured experimentally. The diffraction efficiency over the spectral range, the bandwidth, and the angular selectivity of the grating is measured, analyzed and compared with that of the theoretical ones. The results show that by adjusting and controlling the preparation conditions of DCG plates, the exposure time and the post-processing technique of the grating, the VPH transmission grating with high diffraction efficiency approximate to the design requirement can be obtained. The measured peak diffraction efficiency reaches nearly 85% at central wavelength of 590 nm while the average diffraction efficiency is larger than 75% over the required spectral range from 420 nm to 760 nm.

Li, Ming; Tang, Minxue; Xia, Haohan; Fang, Chunhuan; Wu, Jianhong; Zhao, Xunjie

2010-11-01

205

Sub-wavelength grating gradient index mode transformers in high index contrast slab waveguides  

NASA Astrophysics Data System (ADS)

We report on new types of sub-wavelength grating gradient index structures for efficient mode coupling in high index contrast slab waveguides. Using sub-wavelength gratings (SWGs), an adiabatic transition can be formed at the interface between slab waveguides of different core thicknesses. The SWG transition region minimizes both mode mismatch loss and coupling to higher order modes. By creating the adiabatic gradient effective index region in the direction of propagation, we demonstrate that vertical mode size transformation is readily achieved in structures that can be fabricated using a single etch step. Using 3D finite-difference time-domain simulations we study the loss, polarization dependence and the higher order mode excitation for two types (triangular and triangular-transverse) of SWG transition regions between silicon-on-insulator slab waveguides of different core thicknesses. We also demonstrate two solutions to mitigate polarization dependent loss, namely using a partial transverse SWG and a SWG in the region between the triangular teeth. Our mode transformer designs are optimized for applications in polarization compensator in echelle grating and arrayed waveguide grating (AWG) multiplexers and a gradient index interface between the ridge waveguide and the slab combiner region in a curved waveguide grating demultiplexer.

Bock, P. J.; Cheben, P.; Schmid, J. H.; Xu, D.-X.; Janz, S.; Hall, T. J.

2009-02-01

206

Blazed phononic crystal grating  

NASA Astrophysics Data System (ADS)

It is well known that blazed optical diffraction gratings can significantly increase the diffraction efficiency of plane waves for a selected angle of incidence. We show that by combining blazing with a phononic band gap, diffraction efficiency approaching 100% can be achieved for acoustic waves. We obtain experimentally 98% diffraction efficiency with a two-dimensional phononic crystal of rotated steel rods of square cross-section immersed in water. This result opens the way toward the design of efficient phononic crystal gratings.

Moiseyenko, Rayisa P.; Liu, Jingfei; Declercq, Nico F.; Laude, Vincent

2013-01-01

207

Bragg gratings in ORMOCERs  

NASA Astrophysics Data System (ADS)

Two novel holographic recording media based on silica gel methyl methacrylate (MMA) and hydroxy ethyl methacrylate (HEMA) organically modified ceramics (ORMOCERS) are presented and its holographic properties, inferred from the experimental data, are discussed. The recording of holographic gratings of both low-spatial frequency (50 lp/mm) and high-spatial frequency (1400 lp/mm) in a bulk ORMOCER matrix is reported. The gratings were recorded by UV irradiation-induced photopolymerization of the MMA or HEMA monomers embedded in the silica matrix. The Bragg gratings were successfully recorded by interference of two coherent beams of 351.1 nm wavelength. A linearly polarized He-Ne laser beam (632.8 nm) was used for continuous monitoring of the recording process by measurement of the diffraction efficiency and for enhancement of the grating creation process. High diffraction efficiencies (93%) and low absorption and scattering coefficients were measured during the holographic reconstruction by He-Ne laser beam. The most important holographic parameters of the gratings were inferred from the experimental data: diffraction efficiency, angular selectivity, refraction-index modulation amplitude, spectral sensitivity, the Klein-Cook parameter, and the environmental stability of the gratings.

Belenguer, Tomas D.; Cheben, Pavel; Moreno, Eva M.; Nunez, Armonia; Ulibarrena, Manuel; del Monte, Francisco; Levy, David

1997-10-01

208

Laser driven grating linac  

SciTech Connect

The fields induced over a grating exposed to plane parallel light are explored. It is shown that acceleration is possible if either the particles travel skew to the grating lines, or if the radiation is falling at a skew angle onto the grating. A general theory of diffraction in this skew case is given. In one particular case numerical solutions are worked out for some deep grating. It is found that accelerating fields larger even than the initial fields can be obtained, the limit being set by resistive losses on the grating surface. Simple calculations are made to see what accelerating fields might be obtained using CO/sub 2/ lasers. Accelerations of 2 or 20 GeV per meter seem possible depending on whether the grating is allowed to be destroyed or not. Power requirements, injection and focussing are briefly discussed and no obvious difficulties are seen. It is concluded, therefore, that the proposed mechanism should be considered as a good candidate for the next generation of particle accelerators.

Palmer, R B

1980-01-01

209

Off-plane reflection gratings for Constellation-X  

NASA Astrophysics Data System (ADS)

We present the latest design of an off-plane reflection grating array for the Constellation-X X-ray Grating Spectrometer. The off-plane design can easily demonstrate the baseline requirements of resolution, R > 1250 and throughput, effective area > 1000 cm2 from 0.3 - 1.0 keV. Furthermore, the flexibility of the design allows for several avenues for optimization of these factors. We consider two configurations, 3 m and 9 m from the focal plane using a 20 m focal length telescope. The trade-offs between the two options are discussed.

McEntaffer, Randall L.; Cash, Webster; Shipley, Ann

2008-08-01

210

Pupil aberrations in Offner spectrometers.  

PubMed

The light path function (LPF) of an Offner spectrometer is presented. The evaluation of the LPF of this spectrometer enables its imaging properties to be studied for arbitrary object and image positions, while avoiding the more complicated analysis of intermediate images generated by the diffraction grating, which is often involved. A power series expansion of the LPF on the grating coordinates directly determines pupil aberrations of the generated spectrum and facilitates the search for configurations with small low-order aberrations. This analysis not only confirms the possibility of reducing low-order aberrations in Rowland-type mounts, namely astigmatism and coma, as predicted in previous studies, but also proves that all third-order terms in the series expansion of the aberration function can be canceled at the image of the design point and for the corresponding design wavelength, when the design point is located on a plane orthogonal to the optical axis. Furthermore, fourth-order terms are computed and shown to represent the most relevant contribution to image blurring. Third- and fourth-order aberrations are also evaluated for Rowland mounts with the design point located outside the aforementioned plane. The study described in this manuscript is not restricted to small angles of incidence, and, therefore, it goes beyond Seidel and Buchdahl aberrations. PMID:22472819

González-Núñez, Héctor; Prieto-Blanco, Xesús; de la Fuente, Raúl

2012-04-01

211

Design of a MOEMS-based electromagnetic driven high efficacious phase grating with angle sensor  

NASA Astrophysics Data System (ADS)

A novel design for fabricating the high efficacious rectangular phase grating with angle sensor by MOEMS fabrication process is presented in this paper. The purpose of this design is for increasing the Signal-to-Noise of output signal and reducing the size of near infrared spectrometer by using MOEMS grating. Diffraction efficiency is designed and optimizing at first. We used Fourier optical theory and diffraction optical theory analyzed the diffraction efficiency of the rectangular phase grating, and used the PCgrate simulated the design. After analysis and calculation, we found the best parameter of this grating. According the former design of infrared spectrometer by ZEMAX, the angle resolution of angle sensor is 60mV/°, maximal angle is +/-4.7° and the size of grating is 5x6mm2. Because of the large deflection angle, the electromagnetic force is used for driving this grating. For sensing the grating deflexion angle, we design the angle sensor in the torsion bar of this grating. This sensor is P-type piezoresistive sensor and fabricated on n-(100) high-resistance silicon wafer by boron ion implantation. Analyses stress of torsion bar and piezoresistive angle sensor with Wheatstone bridge theory, the scanning angle ? in a linear relation with output voltages (Vout) of Wheatstone bridge. The size of torsion bar is 2100?mx220?mx75?m, the frequency of first step model is 550Hz. The size of the sensor is 100?mx15?mx0.5?m. Finally, the compatible fabrication process of this device is given. The results of experiments and theory analyzing demonstrate that MOEMS phase grating could work effectively, and angle sensor achieve the real time need. This MOEMS grating is suitable for infrared spectrometer.

Luo, Biao; Wen, Zhi Yu; Chen, Li

2011-06-01

212

Calibration of a High Resolution Soft X-ray Spectrometer  

SciTech Connect

A high resolution grating spectrometer (HRGS) with 2400 line/mm variable line spacing grating for the 10-50 {angstrom} wavelength range has been designed for laser-produced plasma experiments at the Lawrence Livermore National Laboratory (LLNL). The spectrometer has a large radius of curvature, R=44.3 m, is operated at a 2{sup o} grazing angle and can record high signal-to-noise spectra when used with a low-noise, cooled, charge-coupled device detector. The instrument can be operated with a 10-25 {micro}m wide slit to achieve the best spectral resolving power on laser plasma sources, approaching 2000, or in slitless mode with a small symmetrical emission source. Results will be presented for the spectral response of the spectrometer cross-calibrated at the LLNL Electron Beam Ion Trap facility using the broadband x-ray energy EBIT Calorimeter Spectrometer (ECS).

Dunn, J; Beiersdorfer, P; Brown, G V; Magee, E W

2010-01-26

213

Design and operation of the Pioneer Venus Orbiter ultraviolet spectrometer  

Microsoft Academic Search

The University of Colorado's ultraviolet spectrometer instrument carried on the Pioneer Venus Orbiter spacecraft is a 125-mm f\\/5 Ebert-Fastie design with a 250-mm Cassegrain telescope. The instrument has extensive logic to control the grating motor drive and to adapt the basic spectrometer to the constraints and opportunities of the mission. Success has been achieved in reconciling the conflicting requirements of

A. I. F. Stewart

1980-01-01

214

Preliminary design of IGRINS (Immersion GRating INfrared Spectrograph)  

NASA Astrophysics Data System (ADS)

The Korea Astronomy and Space Science Institute (KASI) and the Department of Astronomy at the University of Texas at Austin (UT) are developing a near infrared wide-band high resolution spectrograph, IGRINS. IGRINS can observe all of the H- and K-band atmospheric windows with a resolving power of 40,000 in a single exposure. The spectrograph uses a white pupil cross-dispersed layout and includes a dichroic to divide the light between separate H and K cameras, each provided with a 2kx2k HgCdTe detector. A silicon immersion grating serves as the primary disperser and a pair of volume phased holographic gratings serve as cross dispersers, allowing the high resolution echelle spectrograph to be very compact. IGRINS is designed to be compatible with telescopes ranging in diameter from 2.7m (the Harlan J. Smith telescope; HJST) to 4 - 8 m telescopes. Commissioning and initial operation will be on the 2.7m telescope at McDonald Observatory from 2013.

Yuk, In-Soo; Jaffe, Daniel T.; Barnes, Stuart; Chun, Moo-Young; Park, Chan; Lee, Sungho; Lee, Hanshin; Wang, Weisong; Park, Kwi-Jong; Pak, Soojong; Strubhar, Joseph; Deen, Casey; Oh, Heeyoung; Seo, Haingja; Pyo, Tae-Soo; Park, Won-Kee; Lacy, John; Goertz, John; Rand, Jared; Gully-Santiago, Michael

2010-07-01

215

Vertical angular selectivity and grating degeneracy of volume holographic gratings  

Microsoft Academic Search

The vertical angular selectivity of volume holographic gratings in photorefractive crystals is investigated both theoretically and experimentally. The vertical selective angle and the shape of the grating degeneracy lines are derived by using a simplified geometrical model relating the k-vector sphere to the reference point plane. The study shows that volume gratings have finite selectivity in vertical direction, so that

Quan Yuan; Shiquan Tao; Zuqing Jiang; Xinchang Yang

1996-01-01

216

Nanofabrication advances for high efficiency critical-angle transmission gratings  

NASA Astrophysics Data System (ADS)

We report several break-through nanofabrication developments enabling high efficiency and high resolving power spectrometers in the soft x-ray band. The device is the critical-angle transmission (CAT) grating, which combines the low mass and relaxed alignment tolerances of a transmission grating with the high broad-band efficiency and high diffraction orders of a blazed reflection grating. Past work successfully demonstrated the CAT grating concept; however, the open-area fraction was often less than 20% whilst more than 50% is desired. This presents numerous nanofabrication challenges including a requirement for a freestanding silicon membrane of ultra high-aspect ratio bars at a period of 200 nanometers with minimal cross support blockage. Furthermore, the sidewalls must be smooth to a few nanometers to efficiently reflect soft x-rays. We have developed a complete nanofabrication process for creating freestanding CAT gratings via plasma-etching silicon wafers with a buried layer of SiO2. This removable buried layer enables combining a record-performance plasma etch for the CAT grating with a millimeter-scale honeycomb structural support to create a large-area freestanding membrane. We have also developed a process for polishing sidewalls of plasma-etched ultra-high aspect ratio nanoscale silicon structures via potassium hydroxide (KOH). This process utilizes the anisotropic etch nature of single crystal silicon in KOH. We developed a novel alignment technique to align the CAT grating bars to the {111} planes of silicon within 0.2 degrees, which enables KOH to etch away sidewall roughness without destroying the structure, since the {111} planes etch approximately 100 times slower than the non-{111} planes. Preliminary results of a combined freestanding grating with polishing are presented to enable efficient diffraction of soft x-rays.

Bruccoleri, Alexander R.; Guan, Dong; Heilmann, Ralf K.; Vargo, Steve; DiPiazza, Frank; Schattenburg, Mark L.

2013-09-01

217

Cinematique a grande et moyenne echelles du milieu interstellaire ionise de la galaxie M33  

Microsoft Academic Search

Des observations Fabry-Perot Halpha, en mode balayage, ont ete faites sur deux champs dans le kiloparsec central de la galaxie Messier 33. Ces donnees ont permis d'investiguer le comportement cinematique a grande et a moyenne echelles des complexes gazeux de cette galaxie, menant a plusieurs resultats interessants. Premierement, les effets de la propagation d'une onde de densite sur la morphologie

Steve Godbout

2003-01-01

218

A Goddard High Resolution Spectrograph Atlas of Echelle Observations of the HGMN Star chi LUPI  

Microsoft Academic Search

Observations of the ultra-sharp-lined, chemically peculiar star chi Lupi taken by the Goddard High Resolution Spectrograph in echelle mode are presented. Thirty-six intervals of the spectral region between 1249 and 2688 Å are covered with resolving powers in the range 75,000-93,000. Line identifications are provided, and the observed spectra are compared with synthetic spectra calculated using the SYNTHE program and

J. C. Brandt; S. R. Heap; E. A. Beaver; A. Boggess; K. G. Carpenter; D. C. Ebbets; J. B. Hutchings; M. Jura; D. S. Leckrone; J. L. Linsky; S. P. Maran; B. D. Savage; A. M. Smith; L. M. Trafton; F. M. Walter; R. J. Weymann; C. R. Proffitt; G. M. Wahlgren; S. G. Johansson; H. Nilsson; T. Brage; M. Snow; T. B. Ake

1999-01-01

219

Designing an acousto-optical spectrometer for Guillermo Haro Astrophysical Observatory  

NASA Astrophysics Data System (ADS)

The Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range . Actually, the classical grating spectrometer with mechanically removable optical filters and diffraction gratings is exploited there. Unfortunately, the regular process of changing the diffraction gratings with different resolutions and recalibrating the spectrometer is inconvenient and wastes expensive time for observations. This is why exploiting an acousto-optical cell as a dynamic dispersive element is practically desirable, because potentially it realizes tuning the spectral resolution and the range of observation electronically and excludes filters. Some aspects of inserting just one dynamic acousto-optical diffraction grating instead of a set of the traditional static diffraction gratings are preliminarily considered.

Shcherbakov, Alexandre S.; Arellanes Bernabe, Adan Omar; Chavushyan, Vahram

2013-09-01

220

High Velocity Outflows in AGNs Observed with Gratings  

NASA Astrophysics Data System (ADS)

Several Active Galactic Nuclei (AGNs) have been reported to harbor fast outflows exceeding 10,000 km s-1, which are detected mostly in their low-resolution CCD X-ray spectra. Only few, however, were detected with high-resolution grating spectrometers. Most of the grating detected outflows have been observed multiple times. In these cases, the absorption spectrum changes are indicating that variability is common among these high-velocity winds. In this paper we revisit the grating observations of PG 1211+143, and PDS 456, and report preliminary results on 4C 74.26. We discuss the spectral variability of the first two sources and its implications to the outflows.

Kaspi, Shai; Behar, Ehud

2010-12-01

221

Dipole radiation into grating structures  

Microsoft Academic Search

We present a detailed electromagnetic analysis for the radiation of an electric source located inside grating structures. Our analysis is based on the differential method and uses the scattering-matrix algorithm. We show that gratings that exhibit periodic modulations along two spatial directions (crossed gratings) enable one to couple out the totality of the light emitted by the source into the

Hervé Rigneault; Fabien Lemarchand; Anne Sentenac

2000-01-01

222

Optical system for high resolution spectrometer/monochromator  

DOEpatents

An optical system for use in a spectrometer or monochromator employing a mirror which reflects electromagnetic radiation from a source to converge with same in a plane. A straight grooved, varied-spaced diffraction grating receives the converging electromagnetic radiation from the mirror and produces a spectral image for capture by a detector, target or like receiver.

Hettrick, Michael C. (Berkeley, CA); Underwood, James H. (Walnut Creek, CA)

1988-01-01

223

High accuracy wavelength calibration for a scanning visible spectrometer  

SciTech Connect

Spectroscopic applications for plasma velocity measurements often require wavelength accuracies {<=}0.2 A. An automated calibration, which is stable over time and environmental conditions without the need to recalibrate after each grating movement, was developed for a scanning spectrometer to achieve high wavelength accuracy over the visible spectrum. This method fits all relevant spectrometer parameters using multiple calibration spectra. With a stepping-motor controlled sine drive, an accuracy of {approx}0.25 A has been demonstrated. With the addition of a high resolution (0.075 arc sec) optical encoder on the grating stage, greater precision ({approx}0.005 A) is possible, allowing absolute velocity measurements within {approx}0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.

Scotti, Filippo; Bell, Ronald E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2010-10-15

224

High accuracy wavelength calibration for a scanning visible spectrometer  

NASA Astrophysics Data System (ADS)

Spectroscopic applications for plasma velocity measurements often require wavelength accuracies <=0.2 A?. An automated calibration, which is stable over time and environmental conditions without the need to recalibrate after each grating movement, was developed for a scanning spectrometer to achieve high wavelength accuracy over the visible spectrum. This method fits all relevant spectrometer parameters using multiple calibration spectra. With a stepping-motor controlled sine drive, an accuracy of ~0.25 A? has been demonstrated. With the addition of a high resolution (0.075 arc sec) optical encoder on the grating stage, greater precision (~0.005 A?) is possible, allowing absolute velocity measurements within ~0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.

Scotti, Filippo; Bell, Ronald E.

2010-10-01

225

The evaluation of a deformable diffraction grating for a stigmatic EUV spectroheliometer  

NASA Astrophysics Data System (ADS)

A high-efficiency, extreme ultraviolet (EUV) imaging spectrometer is constructed and tested. The spectrometer employs a concave toroidal grating illuminated at normal incidence in a Rowland circle mounting and has only one reflecting surface. The toroidal grating has been fabricated by a new technique employing an elastically-deformable sub-master grating replicated in a spherical form and then mechanically distorted to produce the desired aspect ratio of the toroidal surface for stigmatic imaging over the selected wavelength range. The fixed toroidal grating used in the spectrometer is then replicated from this surface. Photographic tests and initial photoelectric tests with a two-dimensional, pulse-counting detector system verify the image quality of the toroidal grating at wavelengths near 600 A. The results of these tests and the basic designs of two instruments which could employ the imaging spectrometer for astrophysical investigations in space are described; i.e., a high-resolution EUV spectroheliometer for studies of the solar chromosphere, transition region, and corona; and an EUV spectroscopic telescope for studies of non-solar objects.

Timothy, J. G.

1987-11-01

226

X-ray resolution tests of an off-plane reflection grating for IXO  

NASA Astrophysics Data System (ADS)

We describe the experimental apparatus in use to test an off-plane reflection grating for the soft x-ray (0.3-1.0 keV) bandpass. The grating is a prototype for the X-ray Grating Spectrometer on the International X-ray Observatory (IXO). It has holographically-ruled radial grooves to match the converging beam of a 6.5 m focal length telescope. Laboratory tests are ongoing, with ray tracing indicating that a resolution (?E/E) >3,000 is achievable across the 0.3-1.0 keV bandpass- the requirement to achieve IXO science goals.

Zeiger, Benjamin R.; Shipley, Ann; Cash, Webster; McEntaffer, Randall

2010-07-01

227

Optical grating coupler biosensors  

Microsoft Academic Search

By incorporating a grating in a planar optical waveguide one creates a device with which the spectrum of guided lightmodes can be measured. When the surface of the waveguide is exposed to different solutions, the peaks in the spectrum shift due to molecular interactions with the surface. Optical waveguide lightmode spectroscopy (OWLS) is a highly sensitive technique that is capable

J Vörös; J. J Ramsden; G Csúcs; I Szendr?; S. M De Paul; M Textor; N. D Spencer

2002-01-01

228

Resonantly Enhanced Grating Coupler.  

National Technical Information Service (NTIS)

An apparatus and method for increasing efficiency of grating couplers are disclosed. The apparatus through the use of a defect or a reflective element allows coupling of light around a normal or nearly normal angle with a high efficiency. The method discl...

A. Scherer J. Witzens

2005-01-01

229

Degradation-Free Spectrometers for Solar EUV Measurements: A Progress Report  

NASA Astrophysics Data System (ADS)

Solar EUV observations will be made using two new degradation-free EUV spectrometers on a sounding rocket flight scheduled for Summer 2010. The two instruments, a rare gas photoionization-based Optics-Free Spectrometer (OFS) and a Dual Grating Spectrometer (DGS), are filter-free and optics-free. OFS can measure the solar EUV spectrum with a spectral resolution comparable to that of grating-based EUV spectrometers. The DGS is designed to provide solar irradiance at Lyman-alpha and He II to overlap EUV observations from SOHO/SEM and SDO/EVE. Electronic and mechanical designs for the flight prototype instruments and results of tests performed with the instruments in the laboratory are reported. The spectrometers are being developed and demonstrated as part of the Degradation Free Spectrometers (DFS) project under NASA’s Low Cost Access to Space (LCAS) program and are supported by NASA Grant NNX08BA12G.

Wieman, S. R.; Judge, D. L.; Didkovsky, L. V.

2009-12-01

230

Development of lightweight blazed transmission gratings and large-area soft x-ray spectrographs  

NASA Astrophysics Data System (ADS)

Large area, high resolving power spectroscopy in the soft x-ray band can only be achieved with a state-of-the-art diffraction grating spectrometer, comprised of large collecting-area focusing optics with a narrow point spread function, large-area high-resolving power diffraction gratings, and small pixel, order sorting x-ray detectors. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Several new mission concepts containing CAT grating based spectrometers (AEGIS, AXSIO, SMART-X) promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit related to the detection and characterization of emission and absorption lines, thereby addressing high-priority questions identified in the Astro2010 Decadal Survey "New Worlds New Horizons". We review the current status of CAT grating fabrication, present recent fabrication results, and describe our plans and technology development roadmap for the coming year and beyond.

Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

2013-09-01

231

Binary gratings with random heights  

SciTech Connect

We analyze the far-field intensity distribution of binary phase gratings whose strips present certain randomness in their height. A statistical analysis based on the mutual coherence function is done in the plane just after the grating. Then, the mutual coherence function is propagated to the far field and the intensity distribution is obtained. Generally, the intensity of the diffraction orders decreases in comparison to that of the ideal perfect grating. Several important limit cases, such as low- and high-randomness perturbed gratings, are analyzed. In the high-randomness limit, the phase grating is equivalent to an amplitude grating plus a ''halo.'' Although these structures are not purely periodic, they behave approximately as a diffraction grating.

Rico-Garcia, Jose Maria; Sanchez-Brea, Luis Miguel

2009-06-01

232

Degradation Free Spectrometers for Solar EUV Measurements  

NASA Astrophysics Data System (ADS)

Solar EUV observations will be made using two new degradation-free EUV spectrometers on a sounding rocket flight scheduled for summer 2012. The two instruments, a rare gas photoionization-based Optics-Free Spectrometer (OFS) and a Dual Grating Spectrometer (DGS), are filter-free and optics-free. OFS can measure the solar EUV spectrum with a spectral resolution comparable to that of grating-based EUV spectrometers. The DGS selectable spectral bandwidth is designed to provide solar irradiance in a 10 nm band centered on the Lyman-alpha 121.6 nm line and a 4 nm band centered on the He-II 30.4 nm line to overlap EUV observations from the SDO/EUV Variability Experiment (EVE) and the SOHO/Solar EUV Monitor (SEM). A clone of the SOHO/SEM flight instrument and a Rare Gas Ionization Cell (RGIC) absolute EUV detector will also be flown to provide additional measurements for inter-comparison. Program delays related to the sounding rocket flight termination system, which was no longer approved by the White Sands Missile Range prevented the previously scheduled summer 2011 launch of these instruments. During this delay several enhancements have been made to the sounding rocket versions of the DFS instruments, including a lighter, simplified vacuum housing and gas system for the OFS and an improved mounting for the DGS, which allows more accurate co-alignment of the optical axes of the DGS, OFS, and the SOHO/SEM clone. Details of these enhancements and results from additional lab testing of the instruments are reported here. The spectrometers are being developed and demonstrated as part of the Degradation Free Spectrometers (DFS) project under NASA's Low Cost Access to Space (LCAS) program and are supported by NASA Grant NNX08BA12G.

Wieman, S. R.; Didkovsky, L. V.; Judge, D. L.; McMullin, D. R.

2011-12-01

233

The double grating monochromator's design for pure rotational Raman lidar  

NASA Astrophysics Data System (ADS)

The pure rotational Raman lidar temperature measurement system is usually used for retrieval of atmospheric temperature according to the echo signal ratio of high and low-level quantum numbers of N2 molecules which are consistent with the exponential relationship. An effective method to detect the rotational Raman spectrum is taking a double grating monochromator. In this paper the detection principle and the structure of the dual-grating monochromator are described, with analysis of rotational Raman's Stokes and anti-Stokes spectrums of N2 molecule, the high order and lower order quantum number of the probe spectrum are resolved, then the specific design parameters are presented. Subsequently spectral effect is simulated with Zemax software. The simulation result indicates that under the condition of the probe laser wavelength of 532nm and using double-grating spectrometer which is comprised by two blazed gratings, Raman spectrums of 529.05nm, 530.40nm, 533.77nm, 535.13nm can be separated well, and double-grating monochromator has high diffraction efficiency.

Ge, Xian-ying; Chen, He; Zhang, Yin-chao; Chen, Si-ying; Guo, Pan; Mu, Tao-tao; Bu, Zhi-chao; Yang, Jian

2013-09-01

234

Thin-foil reflection gratings for Constellation-X  

NASA Astrophysics Data System (ADS)

The Reflection Grating Spectrometer (RGS) on Constellation-X is designed to supply astronomers with high spectral resolution in the soft x-ray band from 0.25 to 2 keV. High resolution, large collecting area and low mass at grazing incidence require very flat and thin grating substrates, or thin-foil optics. Thin foils typically have a diameter-to-thickness ratio of 200 or higher and as a result very low stiffness. This poses a number of technological challenges in the areas of shaping, handling, positioning, and mounting of such optics. The most minute forces (gravity sag, friction, thermal mismatch with optic mount, etc.) can lead to intolerable deformations and limit figure metrology repeatability. We present results of our efforts in the manipulation and metrology of suitable grating substrates, utilizing a novel low-stress foil holder with friction-reducing flexures. A large number of reflection gratings is needed to achieve the required collecting area. We have employed nanoimprint lithography (NIL) - which uses imprint films as thin as 100 nm or less - for the high-fidelity and low-stress replication from 100 mm diameter saw-tooth grating masters.

Heilmann, Ralf K.; Akilian, Mireille; Chang, Chih-Hao; Forest, Craig R.; Joo, Chulmin; Lapsa, Andrew; Montoya, Juan C.; Schattenburg, Mark L.

2004-10-01

235

A single-mode Echelle spectrograph: eliminating modal variation, enabling higher precision Doppler study  

NASA Astrophysics Data System (ADS)

An innovative compact - yet high resolution - cross-dispersed echelle spectrograph has been designed, built, and deployed at TSU's 2-meter robotic telescope for initial tests and commissioning. This design is based on a single mode fiber (SMF) and it eliminates mode noise in fiber-fed spectrographs which is important for m/s precision exoplanet Doppler searches. The use of SMFs removes modal variation, makes the design compact and the camera focus slow and stable at the price of lower throughput. This can be improved by using adaptive optics or by placing it in space; the compact design is well suited for such deployment.

Ghasempour, Askari; Kelly, John; Muterspaugh, Matthew W.; Williamson, Michael H.

2012-09-01

236

Elemental abundance analyses with Complejo Astronomico EL Leoncito REOSC echelle spectrograms  

NASA Astrophysics Data System (ADS)

Elemental abundances are derived for four sharp-lined stars, the Mercury-Manganese stars mu Lep, HR 4817, and 28 Her, and 7 Sex, a Population I star with Population II space motions, using REOSC echelle spectrograms obtained at CASLEO to extend previous studies. Comparisons with published equivalent widths indicate that the CASLEO scale is marginally larger than those of DAO Reticon and KPNO CCD spectra. The CASLEO spectrograms have improved the quality of the abundance determinations. New abundances are found for a few elements.

Adelman, S. J.; Pintado, O. I.

1997-10-01

237

Design of Echelle Spectrograph for small telescopes with commercially available components  

NASA Astrophysics Data System (ADS)

We present the design of an echelle spectrograph based on commercially available components. This instrument is an ideal solution to equip small telescopes with low cost but scientifically effective instrumentation. The spectrograph is fiber fed, reaches a resolution of about 8,000, can be located in a gravity invariant and thermally controlled environment and can be used for the long term spectroscopic monitoring of bright objects. The optical design and performances of the instrument are analyzed using Zemax, we present an option for the mechanical design too.

Chacón, Juan A.; Vanzi, Leonardo; Avila, Gerardo

2010-07-01

238

High resolution instrumentation system for fibre-Bragg grating aerospace sensors  

Microsoft Academic Search

A passive technique for high-resolution detection of the wavelength of peak reflection from fibre Bragg grating (FBG) sensors is presented. The approach, based on a de-convolution of the FBG spectrum and the spectrometer resolution, essentially overcomes the low spectral resolution (?0.1 nm) associated with commercial spectrometers employing CCD detection. The performance of two algorithms, the Centroid Detection algorithm (CDA) and

A Ezbiri; S. E Kanellopoulos; V. A Handerek

1998-01-01

239

Asymmetric acoustic gratings  

NASA Astrophysics Data System (ADS)

The unidirectional transmission of acoustic waves is realized by a simple geometrically asymmetric steel grating structure. This exotic phenomenon stems from the one-way diffraction effect induced by the different periods of the slits on the both surfaces of the sample. And the frequency range of unidirectional transmission is simply determined by the structure periods. The experimental results agree well with the theoretical simulation. This remarkable effect is expected potential applications in ultrasonic devices, such as acoustic rectifiers and acoustic diodes.

He, Zhaojian; Peng, Shasha; Ye, Yangtao; Dai, Zhongwei; Qiu, Chunyin; Ke, Manzhu; Liu, Zhengyou

2011-02-01

240

Lipid multilayer gratings.  

PubMed

The interaction of electromagnetic waves with matter can be controlled by structuring the matter on the scale of the wavelength of light, and various photonic components have been made by structuring materials using top-down or bottom-up approaches. Dip-pen nanolithography is a scanning-probe-based fabrication technique that can be used to deposit materials on surfaces with high resolution and, when carried out in parallel, with high throughput. Here, we show that lyotropic optical diffraction gratings--composed of biofunctional lipid multilayers with controllable heights between approximately 5 and 100 nm--can be fabricated by lipid dip-pen nanolithography. Multiple materials can be simultaneously written into arbitrary patterns on pre-structured surfaces to generate complex structures and devices, allowing nanostructures to be interfaced by combinations of top-down and bottom-up fabrication methods. We also show that fluid and biocompatible lipid multilayer gratings allow label-free and specific detection of lipid-protein interactions in solution. This biosensing capability takes advantage of the adhesion properties of the phospholipid superstructures and the changes in the size and shape of the grating elements that take place in response to analyte binding. PMID:20190751

Lenhert, Steven; Brinkmann, Falko; Laue, Thomas; Walheim, Stefan; Vannahme, Christoph; Klinkhammer, Soenke; Xu, Miao; Sekula, Sylwia; Mappes, Timo; Schimmel, Thomas; Fuchs, Harald

2010-02-28

241

Imaging spectrometer for process industry applications  

NASA Astrophysics Data System (ADS)

This paper presents an imaging spectrometer principle based on a novel prism-grating-prism (PGP) element as the dispersive component and advanced camera solutions for on-line applications. The PGP element uses a volume type holographic plane transmission grating made of dichromated gelatin (DCG). Currently, spectrographs have been realized for the 400 - 1050 nm region but the applicable spectral region of the PGP is 380 - 1800 nm. Spectral resolution is typically between 1.5 and 5 nm. The on-axis optical configuration and simple rugged tubular optomechanical construction of the spectrograph provide a good image quality and resistance to harsh environmental conditions. Spectrograph optics are designed to be interfaced to any standard CCD camera. Special camera structures and operating modes can be used for applications requiring on-line data interpretation and process control.

Herrala, Esko; Okkonen, Jukka T.; Hyvarinen, Timo S.; Aikio, Mauri; Lammasniemi, Jorma

1994-11-01

242

Alignment of Liquid Crystals by Surface Gratings.  

National Technical Information Service (NTIS)

Square-wave grating structures with periodicities ranging from 3200 A to 12 micrometers were etched into fused quartz substrates, and the effect of such gratings on liquid crystal alignment was studied. Gratings with periodicities below 4 micrometers appe...

D. C. Shaver

1979-01-01

243

Elliptical varied line-space (EVLS) gratings  

NASA Astrophysics Data System (ADS)

Imaging spectroscopy at wavelengths below 2000 Å offers an especially powerful method for studying many extended high-temperature astronomical objects, like the Sun and its outer layers. But the technology to make such measurements is also especially challenging, because of the poor reflectance of all standard materials at these wavelengths, and because the observation must be made from above the absorbing effects of the Earth's atmosphere. To solve these problems, single-reflection stigmatic spectrographs for XUV wavelengths have bee flown on several space missions based on designs with toroidal uniform line-space (TULS) or spherical varied line-space (SVLS) gratings that operate at near normal-incidence. More recently, three solar EUV/UV instruments have been selected that use toroidal varied line-space (TVLS) gratings; these are SUMI and RAISE, both sounding rocket payloads, and NEXUS, a SMEX satellite-mission. The next logical extension to such designs is the use of elliptical surfaces for varied line-space (EVLS) rulings. In fact, EVLS designs are found to provide superior imaging even at very large spectrograph magnifications and beam-speeds, permitting extremely high-quality performance in remarkably compact instrument packages. In some cases, such designs may be optimized even further by using a hyperbolic surface for the feeding telescope. The optical characteristics of two solar EUV spectrometers based on these concepts are described: EUS and EUI, both being developed as possible instruments for ESA's Solar Orbiter mission by consortia led by RAL and by MSSL, respectively.

Thomas, Roger J.

2004-10-01

244

Electronically Tunable Grating-Gate Terahertz Detectors  

NASA Astrophysics Data System (ADS)

Spectroscopy in the millimeter-wave to THz frequencies has received a great deal of recent interest for security applications and chemical identification. This talk will address detectors that utilize plasmons in high-mobility GaAs/AlGaAs quantum well structures to provide a frequency tunable detector response. In particular, recent advances on the grating-gate detector, including membrane and split-gate versions, will be presented. The discussion will include our understanding of the detection mechanisms involved as well as the noise equivalent powers that have been achieved in the various geometries. Currently, the grating-gate style of detector covers a frequency range from 150GHz to 1THz at temperatures ranging from 4K to 80K, however, the ultimate frequency and temperature limits of these detectors are not currently known. The ability to tune the detector response by simply changing a gate voltage leads to an attractive `spectrometer-on-a-chip' where no moving parts would be needed for THz spectral analysis. To date we have achieved spectral scans from 600GHz to 1THz in 12.5ms with a measured 15GHz minimum linewidth. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Shaner, E. A.; Wanke, M. C.; Lee, Mark; Grine, A. D.; Reno, J. L.; Allen, S. J.

2007-03-01

245

CEBAF superconducting spectrometer design  

Microsoft Academic Search

The CEBAF Experimental Nuclear Physics Program is based upon three independent facilities each with unique capabilities. Hall A consists of a pair of High Resolution Spectrometers (HRS), Hall B features a Large Acceptance Spectrometer (LAS) and Hall C will have a high acceptance, high energy electron spectrometer and matching special purpose hadron spectrometer. The performance and operational of these devices

P. Brindza; J. Alcorn; R. Carlini; L. Harwood; J. Lerose; B. Mecking; J. Mougey; J. O'Meara

1989-01-01

246

Development of an ultrahigh-resolution diffraction grating for soft x-rays  

NASA Astrophysics Data System (ADS)

Resonant Inelastic X-ray Scattering (RIXS) is the one of the most powerful methods for investigation of the electronic structure of materials, specifically of excitations in correlated electron systems. However the potential of the RIXS technique has not been fully exploited because conventional grating spectrometers have not been capable of achieving the extreme resolving powers that RIXS can utilize. State of the art spectrometers in the soft x-ray energy range achieve ~0.25 eV resolution, compared to the energy scales of soft excitations and superconducting gap openings down to a few meV. Development of diffraction gratings with super high resolving power is necessary to solve this problem. In this paper we study the possibilities of fabrication of gratings of resolving power of up to 106 for the 0.5 - 1.5 KeV energy range. This energy range corresponds to all or most of the useful dipole transitions for elements of interest in most correlated electronic systems, i.e. oxygen K-edge of relevance to all oxides, the transition metal L2,3 edges, and the M4,5 edges of the rare earths. Various approaches based on different kinds of diffraction gratings such as deep-etched multilayer gratings, and multilayer coated echelettes are discussed. We also present simulations of diffraction efficiency for such gratings, and investigate the necessary fabrication tolerances.

Voronov, Dmitriy L.; Cambie, Rossana; Feshchenko, Ruslan M.; Gullikson, Eric M.; Padmore, Howard A.; Vinogradov, Alexander V.; Yashchuk, Valeriy V.

2007-10-01

247

Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter  

NASA Astrophysics Data System (ADS)

We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

Deng, Yang; Liu, Yuan; Gao, Dingshan

2011-02-01

248

Variable Spaced Grating (VSG) Snout, Rotator and Rails for use at LLE  

Microsoft Academic Search

The Variable Spaced Grating (VSG) is a spectrometer snout mounted to an X-Ray Framing Camera (XRFC) through the Unimount flange. This equipment already exists and is used at the University of Rochester, Laboratory for Laser Energetics (LLE) facility. The XRFC and the Unimount flange are designed by LLE. The Tilt Rotator fixture that mounts next to the XRFC and the

S K Mukherjee; J A Emig; L V Griffith; R F Heeter; F A House; D L James; M B Schneider; C M Sorce

2010-01-01

249

First application close measurements applying the new hybrid integrated MEMS spectrometer  

NASA Astrophysics Data System (ADS)

Grating spectrometers have been designed in many different configurations. Now potential high volume applications ask for extremely miniaturized and low cost systems. By the use of integrated MEMS (micro electro mechanical systems) scanning grating devices a less expensive single detector can be used in the NIR instead of the array detectors required for fixed grating systems. Meanwhile the design of a hybrid integrated MEMS scanning grating spectrometer has been drawn. The MEMS device was fabricated in the Fraunhofer IPMS own clean room facility. This chip is mounted on a small circuit board together with the detector and then stacked with spacer and mirror substrate. The spectrometer has been realized by stacking several planar substrates by sophisticated mounting technologies. The spectrometer has been designed for the 950nm - 1900nm spectral range and 9nm spectral resolution with organic matter analysis in mind. First applications are considered in the food quality analysis and food processing technology. As example for the use of a spectrometer with this performance the grill process of steak was analyzed. Similar measurement would be possible on dairy products, vegetables or fruit. The idea is a mobile spectrometer for in situ and on site analysis applications in or attached to a host system providing processing, data access and input-output capabilities, disregarding this would be a laptop, tablet, smart phone or embedded platform.

Grüger, Heinrich; Pügner, Tino; Knobbe, Jens; Schenk, Harald

2013-05-01

250

Flat field concave holographic grating with broad spectral region and moderately high resolution.  

PubMed

In order to deal with the conflicts between broad spectral region and high resolution in compact spectrometers based on a flat field concave holographic grating and line array CCD, we present a simple and practical method to design a flat field concave holographic grating that is capable of imaging a broad spectral region at a moderately high resolution. First, we discuss the principle of realizing a broad spectral region and moderately high resolution. Second, we provide the practical method to realize our ideas, in which Namioka grating theory, a genetic algorithm, and ZEMAX are used to reach this purpose. Finally, a near-normal-incidence example modeled in ZEMAX is shown to verify our ideas. The results show that our work probably has a general applicability in compact spectrometers with a broad spectral region and moderately high resolution. PMID:22307123

Wu, Jian Fen; Chen, Yong Yan; Wang, Tai Sheng

2012-02-01

251

Time- and frequency-domain models for Smith-Purcell radiation from a two-dimensional charge moving above a finite length grating  

SciTech Connect

Smith-Purcell radiation (SPR), formed by an electron beam traveling above a grating, is a very promising source of coherent radiation from the THz to the optical regime. We present two theoretical calculations of the SPR from a two-dimensional bunch of relativistic electrons passing above a grating of finite length. The first calculation uses the finite-difference time-domain approach with the total-field/scattered-field procedure for fields incident on the grating. This calculation allows good physical insight into the radiation process and also allows arbitrary geometries to be treated. The second calculation uses an electric-field integral equation method. Good agreement is obtained between these two calculations. The results of these theoretical calculations are then compared with a theoretical formalism based on an infinite-length grating. The latter formalism allows periodic boundary conditions to be rigorously applied. For gratings with less than {approx}50 periods, a significant error in the strength of the radiated field is introduced by the infinite-grating approximation. It is shown that this error disappears asymptotically as the number of periods increases. The Wood-Rayleigh anomalies, predicted in the infinite-grating approximation, were not seen in our finite-grating calculations. The SPR resonance condition is the same in all three formalisms. Numerical examples are presented for an {approx}18 MeV, 50 nC/m, 200 {mu}m bunch traveling 0.6 mm above a ten-period echelle grating having a 2.1-mm periodicity.

Kesar, Amit S.; Hess, Mark; Korbly, Stephen E.; Temkin, Richard J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2005-01-01

252

Holographic grating: a useful tool  

NASA Astrophysics Data System (ADS)

Holography enables us to create various optical elements, in a simply way. They can be used for any purpose that conventional optical elements can be used for. Especially holographic gratings can demonstrate the advantage of such an approach. To make the dense line structure of a grating classically, a special ruling engine had to be used. Instead mechanically ruled grating grooves a hologram of a plane wave with plane reference wave can be recorded. The interference pattern has the form of regular parallel strips - intensity maxims and the grating interval can be changed very simply, by choosing a proper angle between the interfering waves. Exposition allows us to form the grating profile. The contribution is to present some of our results, applicable during educational process (master study - Optics, lasers and optical spectroscopy), too. A holographic grating may become a simple and useful tool to reveal real temporal coherence properties of widely used laser diode modules and determine frequency spacing ?? when more longitudinal modes are generated. Moreover, when choosing a proper angle between two interfering waves creating the grating, the grating interval ? may become less than the wavelength ?, and a sub-wavelength structure can be created in a simply way if a proper recording medium is accessible. That enables us to model light spreading phenomena when approaching sub-wavelength structures.

Senderáková, Dagmar; Drzik, Milan; Strba, Anton; Mesaros, Vladimir

2011-09-01

253

The design of a multi-detector spectrometer for the infrared  

Microsoft Academic Search

A modified Ebert-Fastie spectrometer has been developed for atmospheric temperature sounding applications. The device is described with reference to its resolution, grating, focal-length mirror, mirror, equivalent f-number, and projected area of grating. The images of the entrance slit appear tilted backwards away from the concave mirror. Astigmatism and spherical aberration are reduced by asperizing the mirror. The resolution and f-number

D. G. Koch; J. A. Aubrecht

1978-01-01

254

First in-vivo trials of a fiber Bragg grating based temperature profiling system.  

PubMed

We describe the results of in-vivo trials of a portable fiber Bragg grating based temperature profile monitoring system. The probe incorporates five Bragg gratings along a single fiber and prevents the gratings from being strained. Illumination is provided by a superluminescent diode, and a miniature CCD based spectrometer is used for demultiplexing. The CCD signal is read into a portable computer through a small A/D interface; the computer then calculates the positions of the center wavelengths of the Bragg gratings, providing a resolution of 0.2 degree C. Tests were carried out on rabbits undergoing hyperthermia treatment of the kidney and liver via inductive heating of metallic implants and comparison was made with a commercial Fluoroptic thermometry system. PMID:10938765

Webb, D J; Hathaway, M W; Jackson, D A; Jones, S; Zhang, L; Bennion, I

2000-01-01

255

Polarization gratings allow for real-time and artifact-free circular dichroism measurements  

NASA Astrophysics Data System (ADS)

We propose a simple and innovative diffractive method for circular dichroism (CD) spectroscopy. It enables real-time measurements and suppress the artifacts introduced by anisotropic specimens and nonideal optical elements in conventional CD spectrometers. The method is based on a single cycloidal optical axis grating and takes advantage of its peculiar optical diffraction behavior. We prove that the true CD spectrum of a general anisotropic medium could be measured in the spectral range of interest, exploiting unpolarized white light and the intrinsic spectral selectivity of the grating. Two experimental approaches have been pursued to create the cycloidal optical axis grating, both based on polarization holography and liquid crystal photoaligning technology. The gratings are replicas of the polarization holograms in thin-films of azodyes, either in low molar mass liquid crystal cells or in reactive mesogen layers.

Pagliusi, P.; Lepera, E.; Provenzano, C.; Mazzulla, A.; Cipparrone, G.

2011-05-01

256

Gold transmission gratings with submicrometer periods and thickness > 0. 5. mu. m  

SciTech Connect

Gold gratings with spatial periods of 0.3 and 0.2 ..mu..m have been fabricated in thicknesses of 0.6 and 0.25 ..mu..m, respectively, and used in x-ray spectroscopy and spatial-period-division. Fabrication techniques included: holographic lithography, shadowing, x-ray lithography and gold microplating. Control of linewidth to tolerances of the order of 10 nm has been demonstrated for gratings of 0.2 ..mu..m period. A high resolution imaging spectrometer, composed of a 22x Wolter x-ray microscope in conjunction with a gold transmission grating, was tested. At a wavelength of 0.69 nm a resolving power, lambda/..delta.. lambda, of 200 was demonstrated. Resolution in this case was source size limited. Gratings of 99.5 nm period were exposed in PMMA by x-ray (lambda = 4.5 nm) spatial-period-division.

Ceglio, N.M.; Price, R.H.; Hawryluk, A.M.; Melngailis, J.; Smith, H.I.

1981-12-01

257

The ACE Echelle Spectrograph - A Medium Resolution (R19,333) Fiber-fed Instrument for Meter-class and Smaller Telescopes  

NASA Astrophysics Data System (ADS)

We have designed and implemented two echelle spectrographs for a use on a 0.9-m f/7.5 and a 0.6m f/13.5 Boller & Chivens telescope. The design is readily adaptable to other optical systems. The instruments are used in a remote / robotic environment and it is easily possible to switch between spectroscopy and direct imaging in less than 10 seconds. The spectrograph is divided into three major components. The “Front End” is a module which inserts into a purpose-built filter-box / guider and is responsible for target acquisition and fiber-plate guiding as well as injection of calibration light into the fiber. The “Calibration Module” allows selection of a flat lamp, Thorium-Argon arc or a solar reference fiber. The “Optical Bench” is the actual spectrograph which is fed by a single 50 micron core diameter Polymicro fiber. We have used commercial off-the-shelf optics wherever possible. The optical path is a double-pass system. Light from the fiber passes through a Canon 200mm f/2 lens, through a cross-dispersion prism and to a 70 lines/mm reflection grating. It then returns through the prism and same lens to reach a Hamamatsu thinned back-illuminated 2048 x 512 12 micron CCD. The resulting echellogram has a total of 35 spectral orders covering the wavelength range 3800-9000A with a FWHM of 3.38A/pixel. The total efficiency of the system is around 23%. We discuss further design details and show results from both telescopes.

Mack, Peter

2013-01-01

258

Cinematique a grande et moyenne echelles du milieu interstellaire ionise de la galaxie M33  

NASA Astrophysics Data System (ADS)

Des observations Fabry-Perot Halpha, en mode balayage, ont ete faites sur deux champs dans le kiloparsec central de la galaxie Messier 33. Ces donnees ont permis d'investiguer le comportement cinematique a grande et a moyenne echelles des complexes gazeux de cette galaxie, menant a plusieurs resultats interessants. Premierement, les effets de la propagation d'une onde de densite sur la morphologie et la cinematique des complexes gazeux affectes ont ete mis en evidence. Un examen morphologique des structures, et des gradients cinematiques perpendi-culaires au bras, a grande echelle, suggere la presence de l'onde de densite. De plus, la deprojection du champ de vitesses permet de devoiler une variation azimutale moyenne de 15 km s-1 pour la composante rotative dans la region du bras sud. Deuxiemement, une verification est faite sur la relation entre la dispersion de vitesses globale et le diametre geometrique des complexes gazeux de dimensions intermediaires, montrant que cette relation n'est pas exclusive aux regions H II geantes. La relation determinee ici est similaire a celle des petites regions H II galactiques ainsi qu'a celle d'un echantillon de region H II geantes extragalactiques. La pente de cette relation est de 1.5 +/- 0.6, en accord avec ces deux autres etudes. Ensuite, un echantillon de bulles Wolf-Rayet en expansion est etudie et une comparaison est faite entre celui-ci et certaines etudes precedentes portant sur des bulles galactiques ainsi que dans le Grand Nuage de Magellan. Ceci mene a une critique de la determination d'ages cinematiques et de la sequence evolutive proposee en fonction des types spectraux des etoiles responsables. Finalement, les regions H II classiques de M33 sont investiguees pour reveler deux nouvelles relations entre les parametres cinematiques des distributions de vitesses et de dispersions de vitesses. Ces relations sont: si=7.86+/-1.69+1.62+/- 0.43sc et sc=1.22+/-0.49+0.70+/- 0.12ssi , ou si est la moyenne de la distribution de largeurs de raies, ssi en est la dispersion et sc est la dispersion de la distribution des vitesses radiales, pour un complexe gazeux donne. Ces relations mettent a jour la nature bimodale des mouvements a meme ces objets, consistant de gradients a grande echelle et de turbulence. Deux nouvelles methodes sont proposees pour evaluer la moyenne de la composante turbulente et la valeur maximale de cette derniere. Un catalogue cinematique des grands complexes gazeux de notre etude, et des restes de supernova cinematiquement interessants sont donnes en appendice.

Godbout, Steve

259

Phononic crystal diffraction gratings  

NASA Astrophysics Data System (ADS)

When a phononic crystal is interrogated by an external source of acoustic waves, there is necessarily a phenomenon of diffraction occurring on the external enclosing surfaces. Indeed, these external surfaces are periodic and the resulting acoustic diffraction grating has a periodicity that depends on the orientation of the phononic crystal. This work presents a combined experimental and theoretical study on the diffraction of bulk ultrasonic waves on the external surfaces of a 2D phononic crystal that consists of a triangular lattice of steel rods in a water matrix. The results of transmission experiments are compared with theoretical band structures obtained with the finite-element method. Angular spectrograms (showing frequency as a function of angle) determined from diffraction experiments are then compared with finite-element simulations of diffraction occurring on the surfaces of the crystal. The experimental results show that the diffraction that occurs on its external surfaces is highly frequency-dependent and has a definite relation with the Bloch modes of the phononic crystal. In particular, a strong influence of the presence of bandgaps and deaf bands on the diffraction efficiency is found. This observation opens perspectives for the design of efficient phononic crystal diffraction gratings.

Moiseyenko, Rayisa P.; Herbison, Sarah; Declercq, Nico F.; Laude, Vincent

2012-02-01

260

High resolution echelle spectrographs for the Anglo-Australian Telescope coude focus and William Herschel Telescope Nasmyth focus  

Microsoft Academic Search

An account is given of the innovative design features incorporated in the echelle spectrographs of the Anglo-Australian and William Herschel telescopes, which have been conceived with a view to the matching of the spectrum format to the features of a the University College London Image Photon Counting System. Attention is given to methods employed for the maximization of throughput, including

D. D. Walker; F. Diego; A. Charalambous; C. J. Hirst; A. C. Fish

1986-01-01

261

Design Tradeoffs for a High Spectral Resolution Mid-Infrared Echelle Spectrograph on the Thirty-Meter Telescope.  

National Technical Information Service (NTIS)

A feasibility design study was undertaken to assess the requirements of a mid-infrared echelle spectrograph (MIRES) with a resolving power of 120, 000 and its associated mid-infrared adaptive optics (MIRAO) system on the Thirty-Meter Telescope. Our baseli...

A. T. Tokunaga J. Elias M. Chun M. Richter T. Bond

2006-01-01

262

Measurements on the Zeeman-splitting of analytical lines by means of a continuum source graphite furnace atomic absorption spectrometer with a linear charge coupled device array  

Microsoft Academic Search

A spectrometer for time-resolved high-resolution spectroscopic measurements of line splittings in inverse Zeeman effect corrected atomic absorption spectrometry is presented. The system consists of a continuum source, a longitudinal Zeeman-THGA module, a high-resolution double echelle monochromator, and a linear CCD array. Splitting patterns of atomic lines in a magnetic field have been determined and are compared with theory. The continuum

U. Heitmann; M. Schutz; H. Beckerrob; S. Florek

1996-01-01

263

Progress Report on the Echelon-cross-echelle Spectrograph for Sofia  

NASA Astrophysics Data System (ADS)

The Echelon-cross-Echelle Spectrograph (EXES) is one of the first generation instruments for SOFIA. It provides high, medium, and low spectral resolution in the wavelength region 4.5 to 28.3 microns using a 1024x1024 detector array. With the improved atmospheric transmission afforded by SOFIA, EXES will acquire truly unique data with its high spectral reosolution; data that cannot be replicated by any other ground or space-based mission currently available or planned. EXES has recently moved to NASA Ames Research Center where it will be completed by a team mostly from UC Davis and NASA Ames. We are currently involved with system testing. Our schedule includes two ground-based telescope runs to thoroughly debug the system before our first flights on SOFIA in 2013.

Richter, Matthew; Seifahrt, A.; McKelvey, M.; Ennico-Smith, K.; Lacy, J.

2010-01-01

264

A Laser Frequency Comb System for Absolute Calibration of the VTT Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

A wavelength calibration system based on a laser frequency comb (LFC) was developed in a co-operation between the Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany and the Max-Planck-Institut für Quantenoptik, Garching, Germany for permanent installation at the German Vacuum Tower Telescope (VTT) on Tenerife, Canary Islands. The system was installed successfully in October 2011. By simultaneously recording the spectra from the Sun and the LFC, for each exposure a calibration curve can be derived from the known frequencies of the comb modes that is suitable for absolute calibration at the meters per second level. We briefly summarize some topics in solar physics that benefit from absolute spectroscopy and point out the advantages of LFC compared to traditional calibration techniques. We also sketch the basic setup of the VTT calibration system and its integration with the existing echelle spectrograph.

Doerr, H.-P.; Steinmetz, T.; Holzwarth, R.; Kentischer, T.; Schmidt, W.

2012-10-01

265

Finite element analysis of large lenses for the Keck telescope high-resolution echelle spectrograph  

NASA Astrophysics Data System (ADS)

The finite element analyses of two large lenses for the Keck Telescope High Resolution Echelle Spectrograph are described. The two lenses, one simple lens, and one meniscus, are of fused silica and are approximately 800 mm (30 in.) in diameter. The purpose of the analyses is to determine the deformations of each optic under its own weight, and to identify the simplest, most cost effective mounting cell that will satisfy the optical requirements. Two common radial supports are analyzed, including varieties of hard point and band type mountings. Several types of axial supports are examined including simple three-point mounts, ring mounts, and static deformation mounts. A parametric finite element input routine is described, whereby a solid model and finite element mesh are automatically generated, given the lens diameter, central thickness, and surface radii of curvature. Deformation predictions from the models are compared with theoretical calculations, interferometric testing, and precision profilometry.

Bigelow, Bruce C.

1991-12-01

266

Preflight performance of the Echelon-Cross-Echelle spectrograph for SOFIA  

NASA Astrophysics Data System (ADS)

The Echelon-Cross-Echelle Spectrograph (EXES) is one of the first generation instruments for the Stratospheric Observatory for Infrared Astronomy (SOFIA). The primary goal of EXES is to provide high-resolution, cross-dispersed spectroscopy, with resolutions of 50,000-100,000 and wavelength coverage of 0.5-1.5% between 4.5 ?m and 28.3 ?m. EXES will also have medium (R=5000-25000) and low (R=1500-4000) modes available, as well as a target acquisition imaging mode and a pupil-imaging mode for alignment testing. EXES is scheduled for commissioning flights in February 2014. It will be available to the public for shared-risk observations in SOFIA's Cycle 2. Here we give an overview of the design and capabilities of EXES as well as its laboratory performance to date.

DeWitt, Curtis; Richter, Matthew J.; McKelvey, Mark E.; Seifahrt, Andreas; Case, Michael; Barthel, Joseph; Zell, Peter; Lynch, Dana

2012-09-01

267

Constraining BALQSO Kinematic Luminosity with 4m Mayall/Echelle Spectrograph CIII* Measurements  

NASA Astrophysics Data System (ADS)

We present preliminary analysis of spectra of two broad absorption line quasars (BALQSOs) obtained with the Ritchey-Chretien (RC) and Echelle spectrographs on the 4-meter Mayall telescope at Kitt Peak National Observatory. The correlation between the mass of a supermassive black hole in an AGN and the mass of the host galaxy suggests some feedback mechanism by which quasar activity and galaxy formation are linked. The mass outflows implied by the presence of BALs have been proposed as one possible mechanism. The ratio of the kinetic to bolometric luminosity is a key parameter for assessing this mechanism. We seek constraints on the kinetic luminosities of the quasar outflows in our observed targets based on measurements of the metastable C III* absorption.

McGinnis, Daniel; Gabel, J.; Austerberry, D.; Schmachtenberger, B.

2013-01-01

268

The characteristics of grating structure in magnetic field measurements based on polarization properties of fiber gratings  

Microsoft Academic Search

In this paper the characteristics of grating structure in magnetic field measurements based on differential group delay of fiber gratings are analyzed. Theoretical simulations are realized using the coupled-mode theory and transfer matrix method. The effects of grating parameters of uniform Bragg grating on measurement range and sensitivity are analyzed. The impacts of chirped, phase-shifted and apodized gratings on DGD

Yang Su; Hui Peng; Kui Feng; Yu-quan Li

2009-01-01

269

Reflectance colorimetry measurement system using scanning spectrometer with array detector  

NASA Astrophysics Data System (ADS)

A reflectance colorimetry measurement system is constructed using scanning spectrometer with array detector, and the color measurement can be achieved under 45:0 and 0:45 geometry conditions. Typically, there are two types of spectrometer for colorimetry measurement: the scanning spectrometer with single-channel detector requires point-by-point spectral reading, and the measurement is time consuming; array sensor spectrometer (multichannel spectrometer) can completes the measurement in a few milliseconds, but its spectral resolution and range are limited by the array sensor and the optical elements. This colorimetry measurement system is designed for color calibration service, it using a scanning spectrometer with array detector, which divides the board spectral measurement range into sections, and uses the array detector to measure each section respectively, thus achieving the rapid measurement of spectral data with high resolution and wide wavelength range, so as to realized fast color measurement with high precision. The array sensor of the system using a photo diode array (PDA) with 1024 pixel, having a larger dynamic range and better linearity compared to CCD. The grating is rotated with a precision rotation stage, and the rotation angle is calculated basing the parameters of grating and collimator lens, so as to stitch the spectral data of each measurement section., the measurement signal is mutated at the junction point between measurement sections, due to the rotation angle and the shape of grating efficiency curve. The theoretical analysis and experiment shows that the signal mutation at the junction point can be eliminated by comparison measurement of reflectance.

Sun, Ruoduan; Ma, Yu; Dai, Caihong; Chen, Xiaju

2013-08-01

270

Transformation a Echelle Fixe et Groupe de Renormalisation pour les Objets Fractals et Multifractals  

NASA Astrophysics Data System (ADS)

Dans un premier temps, la description mathematique des fractals et des multifractais est resumee. Une description de quelques-uns des principaux systemes ou apparaissent des spectres d'exposants multifractals est presentee. L'accent est mis sur deux archetypes, le modele de percolation et le modele de rupture dielectrique. Un modele original de cascade multifractale avec interactions inspire des modeles phenomenologiques de la turbulence est presente et son spectre d'exposants calcule analytiquement. Ce travail elargit la classe de modeles pour lesquels on connait le spectre d'exposants exactement. Dans la seconde partie, on trouve une analyse critique de la transformation a echelle fixe. Sont discutees plus particulierement les proprietes que doivent posseder les diagrammes de base pour obtenir une transformation invariante d'echelle. Les differentes hypotheses arbitraires de la theorie sont mises en evidence. L'une de ces hypotheses concerne le traitement auto-coherent des conditions aux frontieres. Considerant cette hypothese comme valable, la theorie utilise la distribution de trous dans un ensemble de Cantor aleatoire. Un calcul exact de cette distribution est donne ici. Enfin, en troisieme et dernier lieu, on retrouve une analyse exhaustive du probleme du crossover dans le modele de percolation avec une resistance non-nulle pour les liens normalement isolants. A l'aide du groupe de renormalisation de Migdal-Kadanoff, on montre qu'il existe un seul exposant de crossover et une seule longueur de coherence. D'autres longueurs de correlation peuvent etre definies, mais elles demeurent dans un rapport fixe le long des axes propres du groupe de renormalisation. La multifractalite est donc, pour ce modele et ceux qui peuvent etre formules de facon analogue, compatible avec l'existence d'une seule longueur de coherence. Ces resultats sont d'application directe pour les proprietes electriques des milieux desordonnes.

Tremblay, Real

271

Polarization of holographic grating diffraction. II. Experiment  

Microsoft Academic Search

The diffraction of volume holographic gratings is investigated experimentally. We report the measured optical and polarization properties of two volume holographic grating samples and the substrate material. Sample A has a single grating and sample B has three gratings. The Mueller matrices of the transmission (t), diffraction (d) and reflection (r) are measured at a wavelength of 632.8 nm. The

Tsu-Wei Nee; Soe-Mie F. Nee; Mark W. Kleinschmit; M. S. Shahriar

2004-01-01

272

Optical characterization of a complex grating profile  

Microsoft Academic Search

The grating studied here, produced by interferographic exposure of photoresist, comprises two gratings, one with twice the period of the other, aligned so that their Bragg vectors are separated by an angle of 0.02°. Thus, as one moves along the grooves, these two gratings locally vary their relative phase. Coating this grating with metal allows the optical characterization of this

Richard A. Watts; J. Roy Sambles; Mike C. Hutley

1998-01-01

273

Novel method for making parabolic grating  

Microsoft Academic Search

We introduce the moving-mask method for fabrication of continuous relief grating with parabolic section profile in this paper. The depth of the grating is nearly equal to 4 micrometers , the diffraction orders from -10 to 10 has uniform intensity, such a grating can be used as multi-splitter. The grating can be concave or convex. The method presented in this

Bo Chen; Lu-Rong Guo; Ji-Yue Tang; Ping Xu; Ming-Bao Zhou

1996-01-01

274

Fiber Bragg grating technology fundamentals and overview  

Microsoft Academic Search

The historical beginnings of photosensitivity and fiber Bragg grating (FBG) technology are recounted. The basic techniques for fiber grating fabrication, their characteristics, and the fundamental properties of fiber gratings are described. The many applications of fiber grating technology are tabulated, and some selected applications are briefly described

Kenneth O. Hill; Gerald Meltz

1997-01-01

275

Single-nanowire surface plasmon gratings.  

PubMed

We demonstrate single-nanowire plasmonic gratings made by focused-ion-beam milling of single Au nanowires. At the optical communication band, a 290 nm diameter Au nanowire with grating length of 15.6 µm offers evident grating features with a transmission dip up to ?3.3 dB. The grating effects in typical Au nanowires with different grating parameters (e.g. grating depth, width and length) are also investigated. Our results suggest a novel approach to one-dimensional plasmonic gratings with high compactness and flexibility, which may find applications in low-dimensional wavelength-selective plasmonic circuits and devices. PMID:22571946

Zhang, Xining; Ma, Zhe; Luo, Rui; Gu, Ying; Meng, Chao; Wu, Xiaoqin; Gong, Qihuang; Tong, Limin

2012-05-10

276

Mars Airborne Prospecting Spectrometer  

NASA Astrophysics Data System (ADS)

One novel approach towards addressing the need for innovative instrumentation and investigation approaches is the integration of a suite of four spectrometer systems to form the Mars Airborne Prospecting Spectrometers (MAPS) for prospecting on Mars.

Steinkraus, J. M.; Wright, M. W.; Rheingans, B. E.; Steinkraus, D. E.; George, W. P.; Aljabri, A.; Hall, J. L.; Scott, D. C.

2012-06-01

277

LonGSp: The Gornergrat longslit infrared spectrometer  

NASA Astrophysics Data System (ADS)

We present a near-infrared cooled grating spectrometer that has been developed at the Arcetri Astrophysical Observatory for the 1.5 m Infrared Telescope at Gornergrat (TIRGO). The spectrometer is equipped with cooled reflective optics and a grating in Littrow configuration. The detector is an engineering grade Rockwell NICMOS3 array (256 X 256 pixels of 40 microns). The scale on the focal plane is 1.73 arcsec/pixel and the field of view along the slit is 70 arcsec. The accessible spectral range is 0.95-2.5 microns with a dispersion, at first order, of about 11.5 Angstroms/pixel. This paper presents a complete description of the instrument, including its optics and cryo-mechanical system, along with astronomical results from test observations, started in 1994. Since January 1996, LonGSp is offered to TIRGO users and employed in several Galactic and extragalactic programs.

Vanzi, L.; Sozzi, M.; Marcucci, G.; Marconi, A.; Mannucci, F.; Lisi, F.; Hunt, L.; Giani, E.; Gennari, S.; Biliotti, V.; Baffa, C.

1997-09-01

278

Optical design of a coastal ocean imaging spectrometer.  

PubMed

We present an optical design for an airborne imaging spectrometer that addresses the unique constraints imposed by imaging the coastal ocean region. A fast (F/1.8) wide field system (36 degrees) with minimum polarization dependence and high response uniformity is required, that covers the spectral range 350-1050 nm with 3 nm sampling. We show how these requirements can be achieved with a two-mirror telescope and a compact Dyson spectrometer utilizing a polarization-insensitive diffraction grating. PMID:18545620

Mouroulis, Pantazis; Green, Robert O; Wilson, Daniel W

2008-06-01

279

Casimir Interaction of Dielectric Gratings  

SciTech Connect

We derive an exact solution for the Casimir force between two arbitrary periodic dielectric gratings and illustrate our method by applying it to two nanostructured silicon gratings. We also reproduce the Casimir force gradient measured recently [H. B. Chan, Y. Bao, J. Zou, R. A. Cirelli, F. Klemens, W. M. Mansfield, and C. S. Pai, Phys. Rev. Lett. 101, 030401 (2008)] between a silicon grating and a gold sphere taking into account the material dependence of the force. We find good agreement between our theoretical results and the measured values both in absolute force values and the ratios between the exact force and proximity force approximation predictions.

Lambrecht, Astrid [Laboratoire Kastler Brossel, CNRS, ENS, UPMC, Campus Jussieu case 74, 75252 Paris (France); Marachevsky, Valery N. [Laboratoire Kastler Brossel, CNRS, ENS, UPMC, Campus Jussieu case 74, 75252 Paris (France); V. A. Fock Institute of Physics, St. Petersburg State University, 198504 St. Petersburg (Russian Federation)

2008-10-17

280

Design of airborne imaging spectrometer based on curved prism  

NASA Astrophysics Data System (ADS)

A novel moderate-resolution imaging spectrometer spreading from visible wavelength to near infrared wavelength range with a spectral resolution of 10 nm, which combines curved prisms with the Offner configuration, is introduced. Compared to conventional imaging spectrometers based on dispersive prism or diffractive grating, this design possesses characteristics of small size, compact structure, low mass as well as little spectral line curve (smile) and spectral band curve (keystone or frown). Besides, the usage of compound curved prisms with two or more different materials can greatly reduce the nonlinearity inevitably brought by prismatic dispersion. The utilization ratio of light radiation is much higher than imaging spectrometer of the same type based on combination of diffractive grating and concentric optics. In this paper, the Seidel aberration theory of curved prism and the optical principles of Offner configuration are illuminated firstly. Then the optical design layout of the spectrometer is presented, and the performance evaluation of this design, including spot diagram and MTF, is analyzed. To step further, several types of telescope matching this system are provided. This work provides an innovational perspective upon optical system design of airborne spectral imagers; therefore, it can offer theoretic guide for imaging spectrometer of the same kind.

Nie, Yunfeng; Xiangli, Bin; Zhou, Jinsong; Wei, Xiaoxiao

2011-11-01

281

Frontiers in High Resolution X- Ray Diagnostics of Plasmas 6.Frontiers in X-Ray Optical Components for HighResolution Spectroscopy and Imaging 6.1Laminar Type Varied-Line-Spacing Holographic Gratings for Soft X-Ray  

Microsoft Academic Search

Laminar-type varied-line-spacing gratings have been widely used for soft x-ray monochromator recently because of the features of low stray lights and higher order lights. We have developed an advanced holographic recording and an ion-beam etching methods for the laminar type varied-line spacing gratings. This report describes a short review of the soft x-ray spectrometers using varied-line-spacing gratings, the fabrication process

Kazuo Sano; Masato Koike

2003-01-01

282

A Broadband Submillimeter Spectrometer using Transition Edge Sensor Bolometers  

Microsoft Academic Search

We present the design and testing of a submillimeter spectrometer based on a helium-cooled scanning Fabry-Perot and superconducting transition edge sensor bolometers. The Fabry-Perot uses a low resolution grating to order sort the incoming light. A linear bolometer array consisting of 16 elements detects this dispersed light, capturing 5 orders simultaneously from one position on the sky. With tuning of

D. J. Benford; B. Maffei; S. H. Moseley; F. Pajot; T. G. Phillips; C. Rioux; R. A. Shafer

2000-01-01

283

Durable silver thin film coating for diffraction gratings  

DOEpatents

A durable silver film thin film coated non-planar optical element has been developed to replace Gold as a material for fabricating such devices. Such a coating and resultant optical element has an increased efficiency and is resistant to tarnishing, can be easily stripped and re-deposited without modifying underlying grating structure, improves the throughput and power loading of short pulse compressor designs for ultra-fast laser systems, and can be utilized in variety of optical and spectrophotometric systems, particularly high-end spectrometers that require maximized efficiency.

Wolfe, Jesse D. (Discovery Bay, CA); Britten, Jerald A. (Oakley, CA); Komashko, Aleksey M. (San Diego, CA)

2006-05-30

284

Development of an ultra-high resolution diffraction grating forsoft x-rays  

SciTech Connect

Resonant Inelastic X-ray Scattering (RIXS) is the one of themost powerful methods for investigation of the electronic structure ofmaterials, specifically of excitations in correlated electron systems.However the potential of the RIXS technique has not been fully exploitedbecause conventional grating spectrometers have not been capable ofachieving the extreme resolving powers that RIXS can utilize. State ofthe art spectrometers in the soft x-ray energy range achieve ~;0.25 eVresolution, compared to the energy scales of soft excitations andsuperconducting gap openings down to a few meV. Development ofdiffraction gratings with super high resolving power is necessary tosolve this problem. In this paper we study the possibilities offabrication of gratings of resolving power of up to 106 for the 0.5 1.5KeV energy range. This energy range corresponds to all or most of theuseful dipole transitions for elements of interest in most correlatedelectronic systems, i.e., oxygen K-edge of relevance to all oxides, thetransition metal L2,3 edges, and the M4,5 edges of the rare earths.Various approaches based on different kinds of diffraction gratings suchas deep-etched multilayer gratings, and multilayer coated echelettes arediscussed. We also present simulations of diffraction efficiency for suchgratings, and investigate the necessary fabricationtolerances.

Voronov, Dmitriy L.; Cambie, Rossana; Feshchenko, Ruslan M.; Gullikson, Eric M.; Padmore, Howard A.; Vinogradov, Alexander V.; Yashchuk, Valeriy V.

2007-08-21

285

Bragg gratings: Optical microchip sensors  

NASA Astrophysics Data System (ADS)

A direct UV writing technique that can create multiple Bragg gratings and waveguides in a planar silica-on-silicon chip is enabling sensing applications ranging from individual disposable sensors for biotechnology through to multiplexed sensor networks in pharmaceutical manufacturing.

Watts, Sam

2010-07-01

286

Monitoring of Laser Material Welding Process Using UV-Visible Spectrometer  

NASA Astrophysics Data System (ADS)

UV-Visible spectrometer is used to record emission from magnesium and titanium metal plates during laser welding processing. Geometrically corrected Czerny-Turner configurations nearly eliminate defocusing problem. The Optikwerks software is used to find the optimum Czerny-Turner configuration and to choose optical elements such as grating types, mirrors focal length and diameter, and slit width. The design parameters of the uv-visible spectrometer in the wavelength range 200-1100 nm for monitoring laser material welding processing.

Genc, B.; Kacar, E.; Akman, E.; Demir, A.

2007-04-01

287

Sounding rocket program aeronomy. Upper Polar Atmosphere Project. Measurements by the infrared spectrometer AB 3  

Microsoft Academic Search

A rocket-borne grating spectrometer system for measuring the fine structure of the 63 micron atomic oxygen transition is described. Thermodynamic equilibria and water vapor concentrations can be determined from these measurements. The system employs an Ebert-Fastie spectrometer. The low signal-to-noise ratio associated with the very low intensities studied led to the use of He cooling. A chopper filter system with

K. U. Grossmann; D. Offerman; J. Scheer

1980-01-01

288

Triple-path collector optics for grazing incident x-ray emission spectrometer  

NASA Astrophysics Data System (ADS)

A new type of collector optics was developed for grazing incident x-ray emission spectrometer. The collector optics used two cylindrical mirrors to add two extra light paths while keeping the center light path that directly illuminates the grating. The design and properties of the spectrometer using the triple-path collector optics were evaluated using ray-tracing simulations, and validity of this design in terms of throughput and energy resolution was confirmed by the experimentally obtained spectra.

Tokushima, T.; Horikawa, Y.; Shin, S.

2011-07-01

289

Alignment of the grating wheel mechanism for a ground-based cryogenic near-infrared astronomy instrument  

NASA Astrophysics Data System (ADS)

We describe the population, optomechanical alignment, and alignment verification of near-infrared gratings on the grating wheel mechanism (GWM) for the Infrared Multi-Object Spectrometer (IRMOS). IRMOS is a cryogenic (80 K), principle investigator-class instrument for the 2.1 m and Mayall 3.8 m telescopes at Kitt Peak National Observatory, and a MEMS spectrometer concept demonstrator for the James Webb Space Telescope. The GWM consists of 13 planar diffraction gratings and one flat imaging mirror (58x57 mm), each mounted at a unique compound angle on a 32 cm diameter gear. The mechanism is predominantly made of Al 6061. The grating substrates are stress relieved for enhanced cryogenic performance. The optical surfaces are replicated from off-the-shelf masters. The imaging mirror is diamond turned. The GWM spans a projected diameter of ~48 cm when assembled, utilizes several flexure designs to accommodate potential thermal gradients, and is controlled using custom software with an off-the-shelf controller. Under ambient conditions, each grating is aligned in six degrees of freedom relative to a coordinate system that is referenced to an optical alignment cube mounted at the center of the gear. The local tip/tilt (Rx/Ry) orientation of a given grating is measured using the zero-order return from an autocollimating theodolite. The other degrees of freedom are measured using a two-axis cathetometer and rotary table. Each grating's mount includes a one-piece shim located between the optic and the gear. The shim is machined to fine align each grating. We verify ambient alignment by comparing grating diffractive properties to model predictions.

Gutkowski, Sharon M.; Ohl, Raymond G.; Hylan, Jason E.; Hagopian, John G.; Kraft, Stephen E.; Mentzell, J. E.; Connelly, Joseph A.; Schepis, Joseph P.; Sparr, Leroy M.; Greenhouse, Matthew A.; MacKenty, John W.

2003-10-01

290

First results from a next-generation off-plane X-ray diffraction grating  

NASA Astrophysics Data System (ADS)

Future NASA X-ray spectroscopy missions will require high throughput, high resolving power grating spectrometers. Off-plane reflection gratings are capable of meeting the performance requirements needed to realize the scientific goals of these missions. We have identified a novel grating fabrication method that utilizes common lithographic and microfabrication techniques to produce the high fidelity groove profile necessary to achieve this performance. Application of this process has produced an initial pre-master that exhibits a radial (variable line spacing along the groove dimension), high density (> 6000 grooves/mm), laminar profile. This pre-master has been tested for diffraction efficiency at the BESSY II synchrotron light facility and diffracts up to 55 % of incident light into usable spectral orders. Furthermore, tests of spectral resolving power show that these gratings are capable of obtaining resolving powers well above 1300 ( ?/? ?) with limitations due to the test apparatus, not the gratings. Obtaining these results has provided confidence that this fabrication process is capable of producing off-plane reflection gratings for the next generation of X-ray observatories.

McEntaffer, Randall; DeRoo, Casey; Schultz, Ted; Gantner, Brennan; Tutt, James; Holland, Andrew; O'Dell, Stephen; Gaskin, Jessica; Kolodziejczak, Jeffrey; Zhang, William W.; Chan, Kai-Wing; Biskach, Michael; McClelland, Ryan; Iazikov, Dmitri; Wang, Xinpeng; Koecher, Larry

2013-08-01

291

Coherent emission of light using stacked gratings  

NASA Astrophysics Data System (ADS)

The possibility of temporally and spatially coherent thermal emission has been demonstrated utilizing stacked gratings. We demonstrate that the metallic grating with narrow air slit behaves like a homogeneous slab with large permittivity and small permeability and find that the interaction between the metallic grating and the Bragg grating gives rise to impendence matching at wavelengths located in the photonic band gap of the Bragg grating, which enables the stacked gratings to perform high emission with ultranarrow spectrum and antenna-like spatial response. This paves the way towards the design of a novel infrared source platform for applications such as thermal analysis, imaging, security, biosensing, and medical diagnoses.

Gong, Yongkang; Liu, Xianliang; Li, Kang; Huang, Jungang; Martinez, J. J.; Rees-Whippey, Daniel; Carver, Sara; Wang, Leiran; Zhang, Wenfu; Duan, Tao; Copner, Nigel

2013-05-01

292

Design tradeoffs for a high spectral resolution mid-infrared echelle spectrograph on the Thirty-Meter Telescope  

Microsoft Academic Search

A feasibility design study was undertaken to assess the requirements of a mid-infrared echelle spectrograph (MIRES) with a resolving power of 120,000 and its associated mid-infrared adaptive optics (MIRAO) system on the Thirty-Meter Telescope. Our baseline design incorporates a 2K×2K Si:As array or array mosaic for the spectrograph and a 1K×1K Si:As array for the slit viewer. Various tradeoffs were

A. T. Tokunaga; T. Bond; J. Elias; M. Chun; M. Richter; M. Liang; J. Lacy; L. Daggert; E. Tollestrup; M. Ressler; D. Warren; S. Fisher; J. Carr

2006-01-01

293

Very Large Telescope\\/Ultraviolet and Visual Echelle Spectrograph and FORS2 spectroscopy of the GRB 081008 afterglow  

Microsoft Academic Search

We aim at studying the gamma-ray burst (GRB), GRB 081008, environment by analysing the spectra of its optical afterglow. Ultraviolet and Visual Echelle Spectrograph\\/Very Large Telescope (UVES\\/VLT) high-resolution spectroscopy of GRB 081008 was secured ˜5 h after the Swift-BAT trigger. Our data set also comprises three VLT\\/FORS2 nearly simultaneous spectra of the same source. The availability of nearly simultaneous high-

V. D'Elia; S. Campana; S. Covino; P. D'Avanzo; S. Piranomonte; G. Tagliaferri

2011-01-01

294

Design of camera and spectrometer dual-use system  

NASA Astrophysics Data System (ADS)

Imaging spectrometers based on prism-grating-prism (PGP) have advantage of direct vision, as a basis for the design of an optical system for a spectrometer and camera dual-use, the system can plug the light splitting element to switch between the spectrometer and camera. This paper has discussed the working principles and structure of the PGP and spectrometer, collimating and focusing lens design principles, then the design result has been presented. The spectral range of the system is 400-800nm, the pixel size of CCD used is 10um × 10um, 1010 × 1018 pixels, the object space numerical aperture is 0.1. In order to reduce the cost and eliminate aberration, collimating lens and focusing lens have symmetric structure, in order to improve the diffraction efficiency, PGP uses the volume phase holographic transmission grating. After optimization the design by ZEMAX software, the whole spectral range resolution is better than 1nm in average, the MTF at Nyquist frequency is greater than 0.7, the length of the whole system is 87mm.

Qi, Yong-hong; Xue, Bin; Zhao, Yi-yi; Tao, Jin-you

2013-08-01

295

Results from the Extended X-ray Off-plane Spectrometer (EXOS) sounding rocket payload  

Microsoft Academic Search

We present results from the Extended X-ray Off-Plane Spectrometer (EXOS) sounding rocket payload. The payload was launched on November 13, 2009 and successfully obtained a spectrum of the Cygnus Loop Supernova Remnant. The instrument observed in the ~20 - 110 Angstrom bandpass with high resolution (~50) by utilizing an offplane reflection grating array. This payload is also the 2nd flight

Phil Oakley; Ben Zeiger; Michael Kaiser; Ann Shipley; Webster Cash; Randall McEntaffer; Ted Schultz

2010-01-01

296

Spurious doubly diffracted radiation in Ebert-Fastie spectrometers: Quantitative influence of instrument parameters  

Microsoft Academic Search

The quantitative influence of geometry, source and detector parameters on observed fluxes is calculated for a typical single-pass in-plane Ebert-Fastie spectrometer, used in the first order of the grating, when unwanted doubly diffracted radiation reaches the exit slit.

G. Marette

1975-01-01

297

[Study on an optical system of small ultraviolet imaging spectrometer with high resolution in broadband].  

PubMed

An ultraviolet imaging spectrometer was studied based on the principle of the small scale ultraviolet spectral instrument. The scheme composed of an off-axis parabolic mirror telescope and a single toroidal grating spectral imaging system was designed. The optimization of the optical system is the optimum processing for the parameters of the toroidal grating. The optical path function and the aberration equations of the grating were analyzed. The perfect anastigmatism conditions and imaging conditions of the single toroidal grating system were obtained. These two conditions that cannot be satisfied by the algebra calculation method limit the field of view and waveband of the spectrometer. The genetic algorithm was introduced to solve the problem. A solar-blind ultraviolet imaging spectrometer for 200-280 nm was designed to verify the design method. The optimum initial configuration was calculated and simulated. A system with F/# 5.7, focal length 102 mm and high spatial resolution was designed. The modulation transfer functions (MTF) of all fields of view are more than 0.65 in the waveband in the required Nyquist frequency (20 1p x mm(-1)). The design results indicate that the optical system theory can be applied to the small scale ultraviolet imaging spectrometer with high resolution and spectral broadband. PMID:23697155

Cong, Hai-Fang; Wang, Chun-Hui; Wang, Yu

2013-02-01

298

An active spectrometer  

Microsoft Academic Search

This article describes a new type of correlation spectrometer, dubbed an ``active spectrometer.'' It utilizes an oscillating mirror in a 1\\/4-m-Rowland circle spectrometer configuration to displace the spectrum periodically in the dispersion direction relative to fixed exit slits. The wavelength of the light passing through each slit is modulated sinusoidally at the mechanical oscillation frequency and its intensity is measured

N. H. Brooks; D. F. Finkenthal; T. H. Jensen; N. N. Naumenko; S. N. Tugarinov

1999-01-01

299

An active spectrometer  

Microsoft Academic Search

This article describes a new type of correlation spectrometer, dubbed an “active spectrometer.” It utilizes an oscillating mirror in a 1\\/4-m-Rowland circle spectrometer configuration to displace the spectrum periodically in the dispersion direction relative to fixed exit slits. The wavelength of the light passing through each slit is modulated sinusoidally at the mechanical oscillation frequency and its intensity is measured

N. H. Brooks; D. F. Finkenthal; T. H. Jensen; N. N. Naumenko; S. N. Tugarinov

1999-01-01

300

SNS backscattering spectrometer, BASIS  

SciTech Connect

We describe the design and current performance of the backscattering silicon spectrometer (BASIS), a time-of-flight backscattering spectrometer built at the spallation neutron source (SNS) of the Oak Ridge National Laboratory (ORNL). BASIS is the first silicon-based backscattering spectrometer installed at a spallation neutron source. In addition to high intensity, it offers a high-energy resolution of about 3.5 {mu}eV and a large and variable energy transfer range. These ensure an excellent overlap with the dynamic ranges accessible at other inelastic spectrometers at the SNS.

Mamontov, Eugene [ORNL; Herwig, Kenneth W [ORNL

2011-01-01

301

Terahertz surface plasmon on chirped groove grating  

Microsoft Academic Search

The excitation of terahertz surface plasmon on metallized chirped groove gratings is studied in time- and frequency-domain. These gratings have a potential to launch and decouple broadband terahertz surface plasmon necessary for integrated optical circuits.

M. Martl; J. Darmo; K. Unterrainer; E. Gornik

2008-01-01

302

The Dawn Mapping Spectrometer: A Virtis-m Heritage  

NASA Astrophysics Data System (ADS)

The Dawn mapping spectrometer (MS) is a rebuild of the VIRTIS mapping spectrom- eter on board the ESA Rosetta mission with an operational duration of more than 2 years and flight time of more than 13 years. VIRTIS is composed of two subsystems: VIRTIS-Mapper (-M) and VIRTIS-High- resolution (-H). -M is characterised by a single optical head consisting of a Shafer telescope combined with an Offner imaging spectrometer and by two bidimensional FPAs: the VIS (0.25-1 µm) and IR (0.95-5 µm). -H is a high-resolution infrared cross-dispersed spectrometer using a prism and a grating. The 2-5 µm spectrum is dispersed in 9 orders on a focal-plane detector ma- trix. The DAWN MS spectrometer will be using only the - M channel of VIRTIS. This will permit a great mass reduction. The design uses a dual channel optical and focal design with mapping ability to 5 µm. The spectrometer consists of only three modules: optical system, 5.0 kg mass; proximity electronics, 3.0 kg and 5 W; cryocooler includ- ing driving electronics, 1.3 kg and 14 W. A 5.0 kg mechanical and thermal mounting, including the cover mechanism for the optics, accommodates the spectrometer subsys- tems. The optical system, which includes foreoptics, dispersive element, filters, focal plane assemblies as well as the cryocooler and proximity electronics is a complete re-build of the VIRTIS-M instrument. As -M, MS does not use beam-splitters. Two different groove densities are ruled on a single grating. The central part of the grating (about 30% of the pupil) is ruled with a higher groove density, which generates the higher spectral resolution needed in the visible channel. The infrared channel utilizes the outer 70% of the grating, which is ruled with a lower dual-shape groove density. The larger collecting area in the IR compensates for the lower solar irradiance in this region. The visible detector array is based on the ATMEL (former Thomson-CSF) type TH 7896 CCD detector. The IR detector used in the MS is based on a bidimen- sional array of IR-sensitive photovoltaic Mercury Cadmium Telluride coupled to sili- con CMOS multiplexer. This detector can operate at temperatures of the order of 75 K. For this reason cryocoolers have to be used.The design fully accomplishes DAWN's scientific and measurement objectives with a simple space-qualified low risk approach and high performance, reliability, heritage and cost effectiveness.

Coradini, A.; de Sanctis, M. C.; Capaccioni, F.; Suetta, E.; Barucci, M. A.; Drossart, P.; Jaumann, R.; McCord, T.; Russell, C. T.; Dawn Team

303

Casimir Interaction of Dielectric Gratings  

NASA Astrophysics Data System (ADS)

We derive an exact solution for the Casimir force between two arbitrary periodic dielectric gratings and illustrate our method by applying it to two nanostructured silicon gratings. We also reproduce the Casimir force gradient measured recently [H. B. Chan, Y. Bao, J. Zou, R. A. Cirelli, F. Klemens, W. M. Mansfield, and C. S. Pai, Phys. Rev. Lett. 101, 030401 (2008)PRLTAO0031-900710.1103/PhysRevLett.101.030401] between a silicon grating and a gold sphere taking into account the material dependence of the force. We find good agreement between our theoretical results and the measured values both in absolute force values and the ratios between the exact force and proximity force approximation predictions.

Lambrecht, Astrid; Marachevsky, Valery N.

2008-10-01

304

Progress on characterization of a dualband IR imaging spectrometer  

NASA Astrophysics Data System (ADS)

A dualband infrared focal plane array is the central component of a compact, low mass, multispectral imaging spectrometer with perfect spectral registration. The prototype spectrometer design uses a grating blaze chosen to be efficient over both 3.75-6.05 and 7.5-12.1 ?m, although the mercury cadmium telluride focal plane array limits the bandwidths with cutoff wavelengths near 5.2 and 10.5 ?m. The spectrometer has been spectrally calibrated with flooded blackbody illumination and offset and gain corrections have been performed. The wavelength resolution is +/-0.024 ?m in the MWIR and +/-0.083 ?m in the LWIR, however this limitation is caused by the calibration method and not by the design. The potential for determining the temperature of a blackbody or greybody from the ratio of two narrow wavebands has been demonstrated.

Beecken, Brian P.; LeVan, Paul D.; Lindh, Cory; Johnson, Randall S.

2008-05-01

305

Computed-tomography imaging spectrometer: experimental calibration and reconstruction results  

NASA Astrophysics Data System (ADS)

A temporally and spatially nonscanning imaging spectrometer is described in terms of computed-tomography concepts, specifically the central-slice theorem. A sequence of three transmission sinusoidal-phase gratings rotated in 60 deg increments achieves dispersion in multiple directions and into multiple orders. The dispersed images of the system's field stop are interpreted as two-dimensional projections of a three-dimensional (x, y, lambda ) object cube. Because of the size of the finite focal-plane array, this imaging spectrometer is an example of a limited-view-angle tomographic system. The imaging spectrometer's point spread function is measured experimentally as a function of wavelength and position in the field of view. Reconstruction of the object cube is then achieved through the maximum-likelihood, expectation-maximization algorithm under the assumption of a Poisson likelihood law. Experimental results indicate that the instrument performs well in the case of broadband and narrow-band emitters.

Descour, Michael; Dereniak, Eustace

1995-08-01

306

Dual transmission grating based imaging radiometer for tokamak edge and divertor plasmas  

NASA Astrophysics Data System (ADS)

The designs of single transmission grating based extreme ultraviolet (XUV) and vacuum ultraviolet (VUV) imaging spectrometers can be adapted to build an imaging radiometer for simultaneous measurement of both spectral ranges. This paper describes the design of such an imaging radiometer with dual transmission gratings. The radiometer will have an XUV coverage of 20-200 A? with a ~10 A? resolution and a VUV coverage of 200-2000 A? with a ~50 A? resolution. The radiometer is designed to have a spatial view of 16°, with a 0.33° resolution and a time resolution of ~10 ms. The applications for such a radiometer include spatially resolved impurity monitoring and electron temperature measurements in the tokamak edge and the divertor. As a proof of principle, the single grating instruments were used to diagnose a low temperature reflex discharge and the relevant data is also included in this paper.

Kumar, Deepak; Clayton, Daniel J.; Parman, Matthew; Stutman, Dan; Tritz, Kevin; Finkenthal, Michael

2012-10-01

307

Modified Schwarzschild imaging spectrometer with a low F-number and a long slit.  

PubMed

A modified Schwarzschild imaging spectrometer utilizing three nonconcentric aspheric mirrors and a plane grating is designed that can handle low F-number, long slit, and broad spectral range. Based on the geometrical aberration theory and Rowland circle condition, the astigmatism-correcting method of the Schwarzschild imaging spectrometer is analyzed. The design procedure of initial parameters is programmed using Matlab software. As an example, a modified Schwarzschild imaging spectrometer operating in 400-1000 nm waveband with F-number of 2.5 and slit length of 13 mm is designed, and good imaging quality is obtained. PMID:24085210

Xue, Qingsheng

2013-10-01

308

Polymer waveguide biosensors with Bragg gratings  

Microsoft Academic Search

Biophotonic sensors based on polymer waveguide with Bragg reflection grating are demonstrated in this work. Waveguide Bragg reflectors were designed by using the effective index method and the transmission matrix method. The grating pattern was formed by exposing laser interference pattern on a photoresist. On top of the inverted rib waveguide, the grating was inscribed into the core layer by

Min-Cheol Oh; Kyung-Jo Kim; Jae-Hyun Lee; Kwang-Nak Koh

2006-01-01

309

High efficiency silicon nitride grating coupler  

NASA Astrophysics Data System (ADS)

In this paper, we have designed, fabricated and characterized silicon nitride grating couplers with high efficiency at 1490 nm. The devices are fabricated using deep UV photolithography with resolution requirement of ˜500 nm. The grating coupler fabricated yields a peak coupling efficiency of -5.1 dB. The 1-dB bandwidth of the grating coupler is 60 nm.

Zhang, Huijuan; Li, Chao; Tu, Xiaoguang; Luo, Xianshu; Yu, Mingbin; Lo, Patrick Guo-Qiang

2013-09-01

310

High-efficiency multilayer dielectric diffraction gratings  

Microsoft Academic Search

The design and performance of a new type of high-efficiency diffraction grating for use in either transmission or reflection are described. The gratings are produced in a multilayer dielectric coating deposited upon optically flat substrates. By proper design of the multilayer stack and grating structure, a diffraction efficiency in excess of 96% for polarized light in the {ital m}=-1 order

M. D. Perry; R. D. Boyd; J. A. Britten; D. Decker; B. W. Shore; C. Shannon; E. Shults

1995-01-01

311

Embedded high-contrast distributed grating structures  

DOEpatents

A new class of fabrication methods for embedded distributed grating structures is claimed, together with optical devices which include such structures. These new methods are the only known approach to making defect-free high-dielectric contrast grating structures, which are smaller and more efficient than are conventional grating structures.

Zubrzycki, Walter J. (Albuquerque, NM); Vawter, Gregory A. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM)

2002-01-01

312

The Chandra HETGS X-Ray Grating Spectrum of ? Carinae  

NASA Astrophysics Data System (ADS)

? Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive colliding-wind binary system. The Chandra X-ray observatory has obtained a calibrated high-resolution X-ray spectrum of the star, uncontaminated by the nearby extended soft X-ray emission. Our 89 ks Chandra observation with the High-Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is nonisothermal. The temperature distribution may represent the emission on either side of the colliding-wind bow shock, effectively ``resolving'' the shock. If so, the preshock wind velocities are ~700 and ~1800 km s-1 in our analysis, and these velocities may be interpreted as the terminal velocities of the winds from ? Carinae and from the hidden companion star. The forbidden-to-intercombination (f/i) line ratios for the He-like ions of S, Si, and Fe are large, indicating that the line-forming region lies far from the stellar photosphere. The iron fluorescent line at 1.93 Å, first detected by ASCA, is clearly resolved from the thermal iron line in the Chandra grating spectrum. The Fe fluorescent line is weaker in our Chandra observation than in any of the ASCA spectra. The Chandra observation also provides an uninterrupted, high time resolution light curve of the stellar X-ray emission from ? Carinae and suggests that there was no significant coherent variability during the Chandra observation. The ? Carinae Chandra grating spectrum is unlike recently published X-ray grating spectra of single massive stars in significant ways and is generally consistent with colliding-wind emission in a massive binary.

Corcoran, M. F.; Swank, J. H.; Petre, R.; Ishibashi, K.; Davidson, K.; Townsley, L.; Smith, R.; White, S.; Viotti, R.; Damineli, A.

2001-12-01

313

Advanced Mass Spectrometer.  

National Technical Information Service (NTIS)

The Advanced Mass Spectrometer (AMS) is a state-of-the-art ion microprobe with fine primary ion beam focus and a unique mass spectrometer. A variable inhomogeneity magnet system, with 288 detectors, all serviced by computer data handling, provides the hea...

F. Halliday J. D. Stein

1977-01-01

314

Improved multisphere spectrometer system  

Microsoft Academic Search

Shonka Research Associated undertook a research program to improve the capabilities and ease of use of the Bonner sphere spectrometer system. Two key elements formed the heart of this research: replacement of the lithium iodide (LiI(Eu)) detector normally used in the spectrometer system with a spherical boron triflouride (BFâ) proportional counter and exploitation of an optimized set of nested polyethylene

J. J. Shonka; S. O. Schwahn; P. E. Rogers; C. J. Misko

1991-01-01

315

One-dimensional space resolving flat-field holographic grating soft x-ray framing camera spectrograph for laser plasma diagnostics.  

PubMed

A 1D space resolving x-ray spectrum diagnostic system has been developed to study the radiation opacity of hot plasma on SG-II laser facility. The diagnostic system consists of a 2400 lines/mm flat-field holographic grating and a gated microchannel plate coupled with an optical CCD and covers the wavelength range of 5-50 A?. The holographic grating was compared with a ruled one by measuring the emission spectra from a laser-produced molybdenum plasma. The results indicate that the holographic grating possesses better sensitivity than the ruled grating having nearly similar spectral resolution. The spectrograph has been used in radiative opacity measurement of Fe plasma. Simultaneous measurements of the backlight source and the transmission spectrum in appointed time range in one shot have been accomplished successfully with the holographic grating spectrometer. The 2p-3d transition absorption of Fe plasma near 15.5 A? in has been observed clearly. PMID:21528997

Xiong, Gang; Hu, Zhimin; Li, Hang; Zhao, Yang; Shang, Wanli; Zhu, Tuo; Wei, Minxi; Yang, Guohong; Zhang, Jiyan; Yang, Jiamin

2011-04-01

316

One-dimensional space resolving flat-field holographic grating soft x-ray framing camera spectrograph for laser plasma diagnostics  

SciTech Connect

A 1D space resolving x-ray spectrum diagnostic system has been developed to study the radiation opacity of hot plasma on SG-II laser facility. The diagnostic system consists of a 2400 lines/mm flat-field holographic grating and a gated microchannel plate coupled with an optical CCD and covers the wavelength range of 5-50 A. The holographic grating was compared with a ruled one by measuring the emission spectra from a laser-produced molybdenum plasma. The results indicate that the holographic grating possesses better sensitivity than the ruled grating having nearly similar spectral resolution. The spectrograph has been used in radiative opacity measurement of Fe plasma. Simultaneous measurements of the backlight source and the transmission spectrum in appointed time range in one shot have been accomplished successfully with the holographic grating spectrometer. The 2p-3d transition absorption of Fe plasma near 15.5A in has been observed clearly.

Xiong Gang; Hu Zhimin; Li Hang; Zhao Yang; Shang Wanli; Zhu Tuo; Wei Minxi; Yang Guohong; Zhang Jiyan; Yang Jiamin [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China)

2011-04-15

317

The Chandra HETGS X-Ray Grating Spectrum of eta Carinae  

Microsoft Academic Search

eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive colliding-wind binary system. The Chandra X-ray observatory has obtained a calibrated high-resolution X-ray spectrum of the star, uncontaminated by the nearby extended soft X-ray emission. Our 89 ks Chandra observation with the High-Energy Transmission Grating Spectrometer (HETGS) shows that the

M. F. Corcoran; J. H. Swank; R. Petre; K. Ishibashi; K. Davidson; L. Townsley; R. Smith; S. White; R. Viotti; A. Damineli

2001-01-01

318

The Chandra HETGS X-ray Grating Spectrum of eta Carinae  

Microsoft Academic Search

eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The Chandra X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emisssion. Our 89 ksec Chandra observation with the High Energy Transmission Grating Spectrometer (HETGS) shows

M. F. Corcoran; J. H. Swank; R. Petre

2001-01-01

319

The CHANDRA HETGS X-ray Grating Spectrum ofCarinae  

Microsoft Academic Search

Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emisssion. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that

M. F. Corcoran; J. H. Swank; R. Petre; K. Ishibashi; K. Davidson; L. Townsley

320

Chandra X-ray Grating Observation Of The Weak-lined T Tau Binary HDE 245059  

Microsoft Academic Search

We present the Chandra High Energy Transmission Grating Spectrometer (HETGS) observation of HDE 245059. Our target is a young weak-lined T Tauri star (WTTS), member of the pre-main sequence group near Lambda Orionis (d 400 pc). HDE 245059 is among the brightest WTTS in the X-ray domain (log Lx 32 erg\\/s); previous ROSAT and ASCA observations showed a typical plasma

Carla Baldovin Saavedra; M. Audard; G. Duchêne; M. Güdel; S. L. Skinner; F. B. S. Paerels

2007-01-01

321

A 5-m grating spectrograph for studying molecular X-ray fluorescence spectra  

NASA Astrophysics Data System (ADS)

The construction of a variable grazing incidence 5-m focal length grating spectrograph, fitted with a thin window Henke X-ray tube, is described. It is reported that with a closely coupled sample to anode arrangement the speed of the instrument at 0 K emission at equivalent instrumental resolution is approximately on par with a 2-m spectrometer's response that uses the DORIS storage ring at DESY as a source.

Andermann, G.; Bergknut, L.; Griesehaber, G.; Smith, J.; Karras, M.

1980-06-01

322

The science case of the PEPSI high-resolution echelle spectrograph and polarimeter for the LBT  

NASA Astrophysics Data System (ADS)

We lay out the scientific rationale for and present the instrumental requirements of a high-resolution adaptive-optics Echelle spectrograph with two full-Stokes polarimeters for the Large Binocular Telescope (LBT) in Arizona. Magnetic processes just like those seen on the Sun and in the space environment of the Earth are now well recognized in many astrophysical areas. The application to other stars opened up a new field of research that became widely known as the solar-stellar connection. Late-type stars with convective envelopes are all affected by magnetic processes which give rise to a rich variety of phenomena on their surface and are largely responsible for the heating of their outer atmospheres. Magnetic fields are likely to play a crucial role in the accretion process of T-Tauri stars as well as in the acceleration and collimation of jet-like flows in young stellar objects (YSOs). Another area is the physics of active galactic nucleii (AGNs) , where the magnetic activity of the accreting black hole is now believed to be responsible for most of the behavior of these objects, including their X-ray spectrum, their notoriously dramatic variability, and the powerful relativistic jets they produce. Another is the physics of the central engines of cosmic gamma-ray bursts, the most powerful explosions in the universe, for which the extreme apparent energy release are explained through the collimation of the released energy by magnetic fields. Virtually all the physics of magnetic fields exploited in astrophysics is somehow linked to our understanding of the Sun's and the star's magnetic fields.

Strassmeier, K. G.; Pallavicini, R.; Rice, J. B.; Andersen, M. I.

2004-05-01

323

Cool stars: spectral library of high-resolution echelle spectra and database of stellar parameters  

NASA Astrophysics Data System (ADS)

During the last years our group have undertake several high resolution spectroscopic surveys of nearby FGKM stars with different spectrographs (FOCES, SARG, SOFIN, FIES, HERMES). A large number of stars have been already observed and we have already determined spectral types, rotational velocities as well as radial velocities, Lithium abundance and several chromospheric activity indicators. We are working now in a homogeneous determination of the fundamental stellar parameters (T_{eff}, log{g}, ? and [Fe/H]) and chemical abundances of many elements of all these stars. Some fully reduced spectra in FITS format have been available via ftp and in the {http://www.ucm.es/info/Astrof/invest/actividad/spectra.html}{Worl Wide Web} (Montes et al. 1997, A&AS, 123, 473; Montes et al. 1998, A&AS, 128, 485; and Montes et al. 1999, ApJS, 123, 283) and some particular spectral regions of the echelle spectra are available at VizieR by López-Santiago et al. 2010, A&A, 514, A97. We are now working in made accessible all the spectra of our different surveys in a Virtual Observatory ({http://svo.cab.inta-csic.es/}{VO}) compliant library and database accessible using a common web interface following the standards of the International Virtual Observatory Alliance ({http://www.ivoa.net/}{IVOA}). The spectral library includes F, G, K and M field stars, from dwarfs to giants. The spectral coverage is from 3800 to 10000 Å, with spectral resolution ranging from 40000 to 80000. The database will provide in addition the stellar parameters determined for these spectra using {http://cdsads.u-strasbg.fr/abs/2012arXiv1205.4879T}{StePar} (Tabernero et al. 2012, A&A, 547, A13).

Montes, D.

2013-05-01

324

Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source  

NASA Astrophysics Data System (ADS)

We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.

Bakeman, M. S.; van Tilborg, J.; Sokollik, T.; Baum, D.; Ybarrolaza, N.; Duarte, R.; Toth, C.; Leemans, W. P.

2010-10-01

325

[Research on key technologies of all fiber optic Fourier transform spectrometer].  

PubMed

A noval all fiber optic Fourier transform spectrometer based on single mode fiber Mach-Zehnder interferometer is reported. The authors designed a piezoelectric optical phase modulator with two centimeter scan scale, which was used to replace the moving mirror of traditonal Fourier transform spectrometer. The 1 310 nm DFB laser was used as reference light source to make equal interval sampling of test light source's interferogram, and to eliminate errors of nonlinear modulation. Through making the inverse Fourier transform to test light source's interferogram, the authors obtained the spectrum of test source. The spectrum of ASE broadband light source was measured by FFTS system, and the experiment result agrees with that tested by grating spectrometer. Finally, the authors utilized fiber grating as sample to measure the resolution of FFTS system, and the spectral resolution is 0.78 cm(-1). PMID:19798938

Wang, An; Zhu, Ling; Zhang, Long; Liu, Yong; Zhu, Zhen; Li, Zhi-Gang; Wu, Jian-Dong; Fan, Yan-Ping

2009-07-01

326

Degradation-Free Spectrometers For Solar EUV Measurements: A Progress Report  

NASA Astrophysics Data System (ADS)

Degradation-Free Spectrometers (DFS) is a new NASA Low Cost Access to Space Project with the goal to build and fly test two new instruments for solar EUV measurements. The first instrument is an Optics Free Spectrometer (OFS) with significant improvements over the version flown previously. The second instrument is a Dual Grating Spectrometer (DGS) based on two highly stable transmission diffraction gratings.Significant progress in preparation of both instruments for laboratory tests and calibrations as well as in the design of OFS and DGS flight electronics will be presented. Preparation of the required paper work for our upcoming Sounding Rocket flights is near completion. This work was supported by NASA grant NNX08BA12G.

Didkovsky, Leonid V.; Wieman, S.; Judge, D.

2009-05-01

327

Programmable spectrometer using MOEMS devices for space applications  

NASA Astrophysics Data System (ADS)

A new class of spectrometer can be designed using programmable components such as MOEMS which enable to tune the beam in spectral width and central wavelength. It becomes possible to propose for space applications a spectrometer with programmable resolution and adjustable spectral bandwidth. The proposed way to tune the output beam is to use the diffraction effect with the so-called PMDG (Programmable Micro Diffraction Gratings) diffractive MEMS. In that case, small moving structures can form programmable gratings, diffracting or not the incoming light. In the proposed concept, the MOEMS is placed in the focal plane of a first diffracting stage (using a grating for instance). With such implementation, the MOEMS component can be used to select some wavelengths (for instance by reflecting them) and to switch-off the others (for instance by diffracting them). A second diffracting stage is used to recombine the beam composed by all the selected wavelengths. It becomes then possible to change and adjust the filter in ? and ??. This type of implementation is very interesting for space applications (astronomy, Earth observation, planetary observation). Firstly because it becomes possible to tune the filtering function quasi instantaneously. And secondly because the focal plane dimension can be reduced to a single detector (for application without field of view) or to a linear detector instead of a 2D matrix detector (for application with field of view) thanks to a sequential acquisition of the signal.

Viard, Thierry; Buisset, Christophe; Rejeaunier, Xavier; Zamkotsian, Frédéric; Venancio, Luis M. G.

2008-08-01

328

Optical apparatus for forming correlation spectrometers and optical processors  

DOEpatents

Optical apparatus is disclosed for forming correlation spectrometers and optical processors. The optical apparatus comprises one or more diffractive optical elements formed on a substrate for receiving light from a source and processing the incident light. The optical apparatus includes an addressing element for alternately addressing each diffractive optical element thereof to produce for one unit of time a first correlation with the incident light, and to produce for a different unit of time a second correlation with the incident light that is different from the first correlation. In preferred embodiments of the invention, the optical apparatus is in the form of a correlation spectrometer; and in other embodiments, the apparatus is in the form of an optical processor. In some embodiments, the optical apparatus comprises a plurality of diffractive optical elements on a common substrate for forming first and second gratings that alternately intercept the incident light for different units of time. In other embodiments, the optical apparatus includes an electrically-programmable diffraction grating that may be alternately switched between a plurality of grating states thereof for processing the incident light. The optical apparatus may be formed, at least in part, by a micromachining process. 24 figs.

Butler, M.A.; Ricco, A.J.; Sinclair, M.B.; Senturia, S.D.

1999-05-18

329

Calculation of thermal noise in grating reflectors  

NASA Astrophysics Data System (ADS)

Grating reflectors have been repeatedly discussed to improve the noise performance of metrological applications due to the reduction or absence of any coating material. So far, however, no quantitative estimate on the thermal noise of these reflective structures exists. In this work we present a theoretical calculation of a grating reflector’s noise. We further apply it to a proposed third generation gravitational wave detector. Depending on the grating geometry, the grating material, and the temperature, we obtain a thermal noise decrease by up to a factor of 10 compared to conventional dielectric mirrors. Thus the use of grating reflectors can substantially improve the noise performance in metrological applications.

Heinert, D.; Kroker, S.; Friedrich, D.; Hild, S.; Kley, E.-B.; Leavey, S.; Martin, I. W.; Nawrodt, R.; Tünnermann, A.; Vyatchanin, S. P.; Yamamoto, K.

2013-08-01

330

Schlömilch series and grating sums  

Microsoft Academic Search

We consider sums over the set of positive integers relevant to construction of periodic Green's functions for diffraction gratings and similar problems, and provide a general formula for a combination of Bessel functions of complex order and complex powers of distance from the origin. This general formula is investigated in a number of particular cases, and in particular we provide

R. C. McPhedran; N. A. Nicorovici; L. C. Botten

2005-01-01

331

Grating based hybrid silicon lasers  

Microsoft Academic Search

Single wavelength hybrid silicon evanescent lasers are described based on wafer bonding III-V multiple quantum wells to gratings patterned on a silicon waveguide. Distributed Bragg feedback and distributed Bragg reflector lasers are demonstrated integrated with passive silicon waveguides showing thresholds as low as 25mA and output powers as high as 11mW around 1600nm wavelength.

Richard Jones; Alexander W. Fang; Matthew N. Sysak; Brian R. Koch; Erica Lively; Di Liang; Omri Raday; John E. Bowers

2009-01-01

332

Design of a portable microfiber optic spectrometer  

NASA Astrophysics Data System (ADS)

Spectrum examination is widely used in scientific research and production. With the development of scientific research and production, the trend of spectrum examination is from indoor to outdoor in situ examination and on-line monitor. So the spectrometer is required to be more minimal. A new type of portable micro fiber spectrometer, using CCD, blaze grating, and two spherical mirror, a small dispersing system based on crossing Czerny-Turner structure, is designed based on this kind of requirement. By analyzing optical system structure, the relation among parameters of these components has been found out in order to fix basic parameters for miniaturized spectrometer; its working wavelength is 200-910nm. The entire spectrum is detected by a CCD for one time, the selection of CCD is product of Toshiba Corporation, linear charge coupled device (L.CCD) TCD1304AP, then received light signal is converted to an electrical signal. The system's hardware circuit includes CPLD, MCU, the CCD driving timing circuit, signal conditioning circuits, high-speed A/D sampling and transform timing circuit. A new kind of driving and sampling system which is high integrated for multi-channel has been designed by using CPLD (complex programmable logical device) and MCU. In this system, many function modules can be generated by logic cells inside of the CPLD chip, such as the driving pulse of CCD, the driving timing of high-speed A/D sampling converter and storage system and so on. In the end, the A/D results can be transmitted to computer by MCU for storage, processing and analysis. The CPLD is programmed in VHDL and compiled, synthesized, simulated and burned with the helping of the environment of Quartus II. The design of portable micro fiber spectrometer has the feature of wide spectrum range and high resolving power, so the system is especially suitable in the application of portable filed examination.

Tong, Jian-Ping; Yang, Yang; Sui, Cheng-Hua; Xu, Dang-Yang; Wang, Fei

2010-05-01

333

Point-by-point written fiber-Bragg gratings and their application in complex grating designs.  

PubMed

The point-by-point technique of fabricating fibre-Bragg gratings using an ultrafast laser enables complete control of the position of each index modification that comprises the grating. By tailoring the local phase, amplitude and spacing of the grating's refractive index modulations it is possible to create gratings with complex transmission and reflection spectra. We report a series of grating structures that were realized by exploiting these flexibilities. Such structures include gratings with controlled bandwidth, and amplitude- and phase-modulated sampled (or superstructured) gratings. A model based on coupled-mode theory provides important insights into the manufacture of such gratings. Our approach offers a quick and easy method of producing complex, non-uniform grating structures in both fibres and other mono-mode waveguiding structures. PMID:20940876

Marshall, Graham D; Williams, Robert J; Jovanovic, Nemanja; Steel, M J; Withford, Michael J

2010-09-13

334

[Design and simulation of the NIR micro-spectrometer optical system].  

PubMed

Based on the working principle of analyzing spectrometer and the theory of optical design, to make the system miniature, and with a certain spectral range and resolution requirements as specific design objectives, a cross-C-T micro-structure based on a plane diffraction grating spectrophotometer of the near-infrared spectrometer was put forward; ZEMAX was used for design and optimizing and simulating analysis of micro-near-infrared spectrometer in the optical system. The result showed that the micro-optical system's spectral range was 900-1 700 nm, resolution was < 10 nm, spectrum broadening was 12.74 mm, F number was 8.128 388, and the system volume was 51.26 mmX41.81 mmX22 mm, and these all satisfy the requirements. It solved the micromation of the optical system of the spectrometer, and therefore, contributed to the micromation of the spectrometer itself. PMID:19810569

Wang, Ling-Fang; Wen, Zhi-Yu; Xiang, Xian-Yi

2009-06-01

335

Extreme ultraviolet spectroscopy diagnostics of low-temperature plasmas based on a sliced multilayer grating and glass capillary optics.  

PubMed

New extreme ultraviolet (EUV) spectroscopic diagnostics of relatively low-temperature plasmas based on the application of an EUV spectrometer and fast EUV diodes combined with glass capillary optics is described. An advanced high resolution dispersive element sliced multilayer grating was used in the compact EUV spectrometer. For monitoring of the time history of radiation, filtered fast EUV diodes were used in the same spectral region (>13 nm) as the EUV spectrometer. The radiation from the plasma was captured by using a single inexpensive glass capillary that was transported onto the spectrometer entrance slit and EUV diode. The use of glass capillary optics allowed placement of the spectrometer and diodes behind the thick radiation shield outside the direction of a possible hard x-ray radiation beam and debris from the plasma source. The results of the testing and application of this diagnostic for a compact laser plasma source are presented. Examples of modeling with parameters of plasmas are discussed. PMID:19044684

Kantsyrev, V L; Safronova, A S; Williamson, K M; Wilcox, P; Ouart, N D; Yilmaz, M F; Struve, K W; Voronov, D L; Feshchenko, R M; Artyukov, I A; Vinogradov, A V

2008-10-01

336

Extreme ultraviolet spectroscopy diagnostics of low-temperature plasmas based on a sliced multilayer grating and glass capillary optics  

SciTech Connect

New extreme ultraviolet (EUV) spectroscopic diagnostics of relatively low-temperature plasmas based on the application of an EUV spectrometer and fast EUV diodes combined with glass capillary optics is described. An advanced high resolution dispersive element sliced multilayer grating was used in the compact EUV spectrometer. For monitoring of the time history of radiation, filtered fast EUV diodes were used in the same spectral region (>13 nm) as the EUV spectrometer. The radiation from the plasma was captured by using a single inexpensive glass capillary that was transported onto the spectrometer entrance slit and EUV diode. The use of glass capillary optics allowed placement of the spectrometer and diodes behind the thick radiation shield outside the direction of a possible hard x-ray radiation beam and debris from the plasma source. The results of the testing and application of this diagnostic for a compact laser plasma source are presented. Examples of modeling with parameters of plasmas are discussed.

Kantsyrev, V. L.; Safronova, A. S.; Williamson, K. M.; Wilcox, P.; Ouart, N. D.; Yilmaz, M. F. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Struve, K. W. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Voronov, D. L. [Kharkiv Polytechnical University, Kharkiv 61002 (Ukraine); Feshchenko, R. M.; Artyukov, I. A.; Vinogradov, A. V. [Physical Lebedev Institute, Moscow 119991 (Russian Federation)

2008-10-15

337

Extreme ultraviolet spectroscopy diagnostics of low-temperature plasmas based on a sliced multilayer grating and glass capillary optics  

NASA Astrophysics Data System (ADS)

New extreme ultraviolet (EUV) spectroscopic diagnostics of relatively low-temperature plasmas based on the application of an EUV spectrometer and fast EUV diodes combined with glass capillary optics is described. An advanced high resolution dispersive element sliced multilayer grating was used in the compact EUV spectrometer. For monitoring of the time history of radiation, filtered fast EUV diodes were used in the same spectral region (>13 nm) as the EUV spectrometer. The radiation from the plasma was captured by using a single inexpensive glass capillary that was transported onto the spectrometer entrance slit and EUV diode. The use of glass capillary optics allowed placement of the spectrometer and diodes behind the thick radiation shield outside the direction of a possible hard x-ray radiation beam and debris from the plasma source. The results of the testing and application of this diagnostic for a compact laser plasma source are presented. Examples of modeling with parameters of plasmas are discussed.

Kantsyrev, V. L.; Safronova, A. S.; Williamson, K. M.; Wilcox, P.; Ouart, N. D.; Yilmaz, M. F.; Struve, K. W.; Voronov, D. L.; Feshchenko, R. M.; Artyukov, I. A.; Vinogradov, A. V.

2008-10-01

338

High Resolution Echelle Spectroscopy of Central Stars of Bipolar Planetary Nebulae: Disclosing the Shaping Mechanisms of Asymmetric Planetary Nebulae  

NASA Astrophysics Data System (ADS)

We present ESO NTT high resolution echelle spectroscopy of the central stars (CSs) of eight southern bipolar planetary nebulae (PNe) selected for their asymmetry. Our aim was to determine or place limits on the magnetic fields of the CSs of these nebulae, and hence to explore the role played by magnetic fields in nebular morphology and PN shaping. Overall, our results indicate that if magnetic fields are responsible for shaping bipolar planetary nebulae, these are not required to be greater than a few tens of kilogauss.

Lee, T.-H.; Stanghellini, L.; Ferrario, L.; Wickramasinghe, D. T.

2007-09-01

339

Microbolometer imaging spectrometer.  

PubMed

Newly developed, high-performance, long-wave- and mid-wave-IR Dyson spectrometers offer a compact, low-distortion, broadband, imaging spectrometer design. The design is further accentuated when coupled to microbolometer array technology. This novel coupling allows radiometric and spectral measurements of high-temperature targets. It also serves to be unique since it allows for the system to be aligned warm. This eliminates the need for cryogenic temperature cycling. Proof of concept results are shown for a spectrometer with a 7.5 to 12.0 ?m spectral range and approximately 20 nm per spectral band (~200 bands). Results presented in this Letter show performance for remote hot targets (>200 °C) using an engineering grade spectrometer and IR commercial lens assembly. PMID:22378399

Johnson, William R; Hook, Simon J; Shoen, Steven M

2012-03-01

340

Aerosol Mobility Size Spectrometer.  

National Technical Information Service (NTIS)

A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housi...

J. Wang P. Kulkarni

2004-01-01

341

A Simple Raman Spectrometer.  

ERIC Educational Resources Information Center

Discusses some basic physical ideas about light scattering and describes a simple Raman spectrometer, a single prism monochromator and a multiplier detector. This discussion is intended for British undergraduate physics students. (HM)

Blond, J. P.; Boggett, D. M.

1980-01-01

342

A Simple Raman Spectrometer.  

ERIC Educational Resources Information Center

|Discusses some basic physical ideas about light scattering and describes a simple Raman spectrometer, a single prism monochromator and a multiplier detector. This discussion is intended for British undergraduate physics students. (HM)|

Blond, J. P.; Boggett, D. M.

1980-01-01

343

Advanced astigmatism-corrected tandem Wadsworth mounting for small-scale spectral broadband imaging spectrometer.  

PubMed

Tandem gratings of double-dispersion mount make it possible to design an imaging spectrometer for the weak light observation with high spatial resolution, high spectral resolution, and high optical transmission efficiency. The traditional tandem Wadsworth mounting is originally designed to match the coaxial telescope and large-scale imaging spectrometer. When it is used to connect the off-axis telescope such as off-axis parabolic mirror, it presents lower imaging quality than to connect the coaxial telescope. It may also introduce interference among the detector and the optical elements as it is applied to the short focal length and small-scale spectrometer in a close volume by satellite. An advanced tandem Wadsworth mounting has been investigated to deal with the situation. The Wadsworth astigmatism-corrected mounting condition for which is expressed as the distance between the second concave grating and the imaging plane is calculated. Then the optimum arrangement for the first plane grating and the second concave grating, which make the anterior Wadsworth condition fulfilling each wavelength, is analyzed by the geometric and first order differential calculation. These two arrangements comprise the advanced Wadsworth mounting condition. The spectral resolution has also been calculated by these conditions. An example designed by the optimum theory proves that the advanced tandem Wadsworth mounting performs excellently in spectral broadband. PMID:23292378

Lei, Yu; Lin, Guan-yu

2013-01-01

344

Broadband ferromagnetic resonance spectrometer  

Microsoft Academic Search

The continuous wave ferromagnetic resonance (FMR) spectrometer operating in multioctave (0.05–40 GHz) frequency range has been built to investigate the magnetic properties of thin ferromagnetic films in the temperature range of 4–420 K. The spectrometer has two probeheads: one is the X-band microwave reflection cavity used to perform express room temperature measurements and the other is an in-cryostat microstrip line

V. P. Denysenkov; A. M. Grishin

2003-01-01

345

Broadband ferromagnetic resonance spectrometer  

Microsoft Academic Search

The continuous wave ferromagnetic resonance (FMR) spectrometer operating in multioctave (0.05-40 GHz) frequency range has been built to investigate the magnetic properties of thin ferromagnetic films in the temperature range of 4-420 K. The spectrometer has two probeheads: one is the X-band microwave reflection cavity used to perform express room temperature measurements and the other is an in-cryostat microstrip line

V. P. Denysenkov; A. M. Grishin

2003-01-01

346

The HERMES Spectrometer  

Microsoft Academic Search

The HERMES experiment is collecting data on inclusive and semi-inclusive deep inelastic scattering of polarised positrons from polarised targets of H, D, and 3He. These data give information on the spin structure of the nucleon. This paper describes the forward angle spectrometer built for this purpose. The spectrometer includes numerous tracking chambers (micro-strip gas chambers, drift and proportional chambers) in

K. Ackerstaff; A. Airapetian; N. Akopov; M. Amarian; V. Andreev; E. C. Aschenauer; R. Avakian; H. Avakian; A. Avetissian; B. Bains; S. Barrow; W. Beckhusen; M. Beckmann; E. Belz; Th. Benisch; S. Bernreuther; N. Bianchi; J. Blouw; H. Böttcher; A. Borissov; J. Brack; B. Braun; B. Bray; S. Brons; W. Brückner; A. Brüll; H. J. Bulten; G. P. Capitani; P. Carter; P. Chumney; E. Cisbani; S. Clark; S. Colilli; H. Coombes; G. R. Court; P. Delheij; E. Devitsin; C. W. de Jager; E. De Sanctis; D. De Schepper; P. Di Nezza; M. Doets; M. Düren; A. Dvoredsky; G. Elbakian; J. Emerson; A. Fantoni; A. Fechtchenko; M. Ferstl; D. Fick; K. Fiedler; B. W. Filippone; H. Fischer; H. T. Fortune; J. Franz; S. Frullani; M.-A. Funk; N. D. Gagunashvili; P. Galumian; H. Gao; Y. Gärber; F. Garibaldi; G. Gavrilov; P. Geiger; V. Gharibyan; V. Giordjian; F. Giuliani; A. Golendoukhin; B. Grabowski; G. Graw; O. Grebeniouk; P. Green; G. Greeniaus; M. Gricia; C. Grosshauser; A. Gute; J. P. Haas; K. Hakelberg; W. Haeberli; J.-O. Hansen; D. Hasch; O. Hausser; R. Henderson; Th. Henkes; R. Hertenberger; Y. Holler; R. J. Holt; H. Ihssen; A. Izotov; M. Iodice; H. E. Jackson; A. Jgoun; C. Jones; R. Kaiser; J. Kelsey; E. Kinney; M. Kirsch; A. Kisselev; P. Kitching; H. Kobayashi; E. Kok; K. Königsmann; M. Kolstein; H. Kolster; W. Korsch; S. Kozlov; V. Kozlov; R. Kowalczyk; L. Kramer; B. Krause; A. Krivchitch; V. G. Krivokhijine; M. Kueckes; P. Kutt; G. Kyle; W. Lachnit; R. Langstaff; W. Lorenzon; M. Lucentini; A. Lung; N. Makins; V. Maleev; S. I. Manaenkov; K. Martens; A. Mateos; K. McIlhany; R. D. McKeown; F. Meißner; F. Menden; D. Mercer; A. Metz; N. Meyners; O. Mikloukho; C. A. Miller; M. A. Miller; R. Milner; V. Mitsyn; G. Modrak; J. Morton; A. Most; R. Mozzetti; V. Muccifora; A. Nagaitsev; Y. Naryshkin; A. M. Nathan; F. Neunreither; M. Niczyporuk; W.-D. Nowak; M. Nupieri; P. Oelwein; H. Ogami; T. G. O’Neill; R. Openshaw; V. Papavassiliou; S. F. Pate; S. Patrichev; M. Pitt; H. J. Plett; H. R. Poolman; S. Potashov; D. Potterveld; B. Povh; V. Prahl; G. Rakness; V. Razmyslovich; R. Redwine; A. R. Reolon; R. Ristinen; K. Rith; H. O. Roloff; G. Röper; P. Rossi; S. Rudnitsky; H. Russo; D. Ryckbosch; Y. Sakemi; F. Santavenere; I. Savin; F. Schmidt; H. Schmitt; G. Schnell; K. P. Schüler; A. Schwind; T.-A. Shibata; T. Shin; B. Siebels; A. Simon; K. Sinram; W. R. Smythe; J. Sowinski; M. Spengos; K. Sperber; E. Steffens; J. Stenger; J. Stewart; F. Stock; U. Stößlein; M. Sutter; H. Tallini; S. Taroian; A. Terkulov; D. Thiessen; B. Tipton; V. Trofimov; A. Trudel; M. Tytgat; G. M. Urciuoli; R. Van de Vyver; G. van der Steenhoven; J. J. van Hunen; D. van Westrum; A. Vassiliev; M. C. Vetterli; M. G. Vincter; E. Volk; W. Wander; T. P. Welch; S. E. Williamson; T. Wise; G. Wöbke; K. Woller; S. Yoneyama; K. Zapfe-Düren; T. Zeuli; H. Zohrabian

1998-01-01

347

Efficiency measurements and modeling of the Advanced X-ray Astrophysics Facility (AXAF) high-energy transmission gratings  

NASA Astrophysics Data System (ADS)

As part of the calibration for the High Energy Transmission Grating Spectrometer (HETGS) on AXAF, we conducted several studies at synchrotrons in an effort to measure the resolving power and the quantum efficiency of gratings over a range of x- ray energies. Gratings that have been thoroughly studied can be used as calibration transfer standards at MIT to evaluate the quality and repeatability of our testing procedures. Synchrotron studies also enable us to evaluate our theoretical prediction of grating performance and thereby obtain a more accurate model of the gratings. In this paper we discuss studies made of 0.2 micrometers and 0.4 micrometers period gratings with gold grating bars supported by thin polyimide films. The goal of this experiment was to measure and accurately model the efficiencies of several grating facets over much of the energy range for which they would be used in space. Our tests were performed in January and July of 1994 at the National Synchrotron Light Source at Brookhaven National Laboratory. We used beam line X8A to illuminate sample gratings that were inserted in the UC/SAO Reflectometer Test Station (the same device that is used to study witness samples for the AXAF mirrors). A double crystal monochromator was used to select narrow energy bands over the range 0.6-6 keV. We measured the diffraction efficiencies as a function of energy for the first order x-rays. Results are in good agreement with predicted efficiencies calculated using gold optical constants that we recently measured, and confirm the energy shift of the MIV and MV edges from the standard values, as measured by Blake et al. (J. X-ray Sci. Technol., in press).

Nelson, Christie S.; Markert, Thomas H.; Song, Y. S.; Schattenburg, Mark L.; Graessle, Dale E.; Flanagan, Kathryn A.; Blake, R. L.; Bauer, James M.; Gullikson, Eric M.

1994-09-01

348

CaII H&K to CaII IRT echelle spectra (Montes+, 2000)  

NASA Astrophysics Data System (ADS)

This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical chromospheric activity indicators from the CaII H&K to CaII IRT lines are analysed here for 16 systems. The chromospheric contribution in these lines has been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted H? profile of the very active star HU Vir. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component can be interpreted as arising from microflaring. Red-shifted absorption features in the H? line have been detected in several systems and excess emission in the blue wing of FG UMa was also detected. These features indicate that several dynamical processes, or a combination of them, may be involved. Using the EH?/EH? ratio as a diagnostic we have detected prominence-like extended material viewed off the limb in many stars of the sample, and prominences viewed against the disk at some orbital phases in the dwarfs OU Gem and BF Lyn. The He I D3 line has been detected as an absorption feature in mainly all the giants of the sample. Total filling-in of the He I D3, probably due to microflaring activity, is observed in HU Vir. Self-absorption with red asymmetry is detected in the CaII H&K lines of the giants 12 Cam, FG UMa and BM CVn. All the stars analysed show clear filled-in CaII IRT lines or even notable emission reversal. The small values of the E8542/E8498 ratio we have found indicate CaII IRT emission arises from plage-like regions. Orbital phase modulation of the chromospheric emission has been detected in some systems, in the case of HU Vir evidence of an active longitude area has been found. (5 data files).

Montes, D.; Fernandez-Figueroa, M. J.; de Castro, E.; Cornide, M.; Latorre, A.; Sanz-Forcada, J.

2000-11-01

349

Optimal design of grating-assisted directional couplers  

Microsoft Academic Search

In this paper, a rigorous leaky mode propagation method has been used to investigate the influence of the grating period and grating index profile on the design of grating-assisted directional couplers (GADC's). A detailed explanation of resonance condition and radiation loss in terms of electromagnetic field contribution in the grating region as a function of the grating period and profile

Vittorio M. N. Passaro

2000-01-01

350

An X-ray grazing incidence phase multilayer grating  

Microsoft Academic Search

An X-ray grazing incidence phase multilayer grating, representing a thin grating placed on a multilayer mirror, is proposed. A high efficiency of grating diffraction can be obtained by the possibility of changing the phase shift of the wave diffracted from the multilayer under the Bragg and total external reflection conditions. A grazing incidence phase multilayer grating consisting of Pt grating

V. A. Chernov; N. V. Kovalenko; S. V. Mytnichenko

2001-01-01

351

Planar-grating klystron experiment  

NASA Astrophysics Data System (ADS)

1407_29A coherent radiation source which uses an electron beam to drive a resonator which consists of two short sections of metal grating embedded in a parallel-plate waveguide structure has been operated in the millimeter-wavelength regime. The fields in the first of the grating sections imparts velocity modulation to the beam and the second extracts power from a bunched beam. Thus, the device functions like a two-cavity klystron. However, the open quasi-optical coupling structure can be utilized at wavelengths which are shorter than those that are practicable in a conventional closed cavity klystron design. The electron beam energy and current employed in these experiments are modest (10's of kv and 1-2 A) and the primary motivation for the work is to develop convenient moderate power sources for various applications of millimeter- and submillimeter-wavelength radiation.

Xu, Yian-Sun; Jackson, Jonathan A.; Price, Edwin J.; Walsh, John E.

1991-04-01

352

Athermal silicon subwavelength grating waveguides  

NASA Astrophysics Data System (ADS)

In this paper, athermal subwavelength grating (SWG) waveguides are investigated. Both numerical simulations and experimental results show that a temperature independent behaviour can be achieved by combining two materials with opposite thermo-optic coefficients within the waveguide. SU-8 polymer with a negative thermo-optic coefficient (dn/dT = -1.1x10-4 K-1) is used in our silicon SWG waveguides to compensate for silicon's positive thermo-optic coefficient of 1.9x10-4 K-1. The grating duty ratio required to achieve an athermal behavior is reported to vary as a function of the operating wavelength and the waveguide dimensions. For example, for athermal waveguides of 260 nm in height, duty ratios of 61.3% and 83.3% were calculated for TE and TM polarized light respectively for a 450 nm wide waveguide, compared to ratios of 79% and 90% for a 350 nm wide waveguide. It is also reported that with increasing width, and increasing height, a smaller grating duty ratio is necessary to achieve an athermal behaviour. A smaller fraction of silicon would hence be needed to compensate for the polymer's negative thermo-optic effect in the waveguide core. Subwavelength sidewall grating (SWSG) waveguides are also proposed here as alternatives to high duty ratio SWG waveguides that are required for guiding TM polarized light. Assuming a duty ratio of 50%, the width of the narrow segments for temperature-independent behavior is found by numerical simulations to be 125 nm and 143 nm for TE and TM polarized light, respectively.

Ibrahim, M.; Schmid, J. H.; Cheben, P.; Lapointe, J.; Janz, S.; Bock, P. J.; Densmore, A.; Lamontagne, B.; Ma, R.; Xu, D.-X.; Ye, W. N.

2011-06-01

353

Diffraction gratings for lighting applications  

NASA Astrophysics Data System (ADS)

Sub-micron diffraction gratings have been used for two LED illumination applications. One is to create a transparent see through luminaire which can be used to illuminate and read a paper document or e-book. A second is a light sensor that can be used in a feedback loop to control a multicolor LED lamp. Optical design and experimental proof-of-principle are presented.

Cornelissen, Hugo J.; de Boer, Dick K. G.; Tukker, Teus

2013-09-01

354

SPRED: a multichannel grazing-incidence spectrometer for plasma impurity diagnosis  

SciTech Connect

A compact vacuum ultraviolet spectrometer system has been developed to provide time-resolved impurity spectra from tokamak plasmas. Two interchangeable aberration-corrected toroidal diffraction gratings with flat focal fields provide simultaneous coverage over the ranges 100 to 1100 A or 160 to 1700 A. The detector is an intensified self-scanning photodiode array. Spectral resolution is 2 A with the higher dispersion grating. Minimum readout time for a full spectrum is 20 ms, but up to 7 individual spectral lines can be measured with a 1 ms time resolution. The sensitivity of the system is comparable to that of a conventional grazing incidence monochromator.

Fonck, R.J.; Ramsey, A.T.; Yelle, R.V.

1982-03-01

355

The X-ray observational satellite XMM, its spectrometer, and observations of supernova remnants  

NASA Astrophysics Data System (ADS)

This thesis centers on the reflection grating spectrometer of the XMM observatory: its design, calibration, and impact on the field of X-ray spectroscopy within the context of the spectrometers of the upcoming generation of X-ray observatories, including Chandra and ASTRO-E. The context of experimental X-ray spectroscopy is illustrated through the detailed descriptions of the components comprising each of the new spectrometers and how the components function and interact. Their operational capabilities are illustrated with simulated results of their observations of X-ray sources-all supernova remnants-that highlight each observatory's specialties. XMM's spectrometer design is based on an array of reflection gratings which disperse X-rays to a set of CCD detectors aligned along the dispersion axis in an inverted Rowland circle. An extension to existing scattering theory was developed and experimentally verified in order to characterize the contribution to the line spread function from grating scatter due to surface roughness. This theory predicts the angular redistribution of small angle scattering of light incident on a reflection grating as a function of intrinsic properties of the grating surface-the root mean square height and correlation length of deviations from the ideal surface-and properties of the scattering geometry-incident angle, exit angle, and wavelength. The predictions of the theory were tested and verified in a long beam X-ray testing facility at Columbia's Nevis Labs. The calibration of the two grating arrays was performed at the Panter X-ray testing facility near Munich, Germany. The comprehensive results of this extensive calibration are presented. The physical model of the arrays was based on the ideal Rowland circle design, and also included deviations from ideal positionings, manufacturing tolerances, and assembly of gratings into the array, as well as its operating processes, principally grating scatter. This model was entirely constrained, with no free parameters (with one noted exception) before the calibration campaigns, and was found to be accurate to within Panter's experimental capabilities. Finally, a new analysis of the galactic supernova remnant, W49B, observed by the ASCA observatory in 1993, is presented. The results of this analysis suggest that the morphology of W49B, whose spatial profile was previously not well understood, is clearly shell-like. It is likely very similar to Tycho's remnant in shape, and is of Type Ia as well.

Spodek, Joshua David

356

High-resolution microspectrometer with an aberration-correcting planar grating.  

PubMed

A concept for a highly miniaturized spectrometer featuring a two-component design is presented. The first component is a planar chip that integrates an input slit and aberration-correcting diffraction grating with an image sensor and is fabricated using microelectromechanical systems (MEMS) technologies. Due to the fabrication in a simple MEMS batch process the essential elements of the spectrometer are automatically aligned, and a low fabrication cost per device can be achieved. The second component is a spherical mirror, which is the only external part. The optimized grating structure compensates for aberrations within the spectrometer operating range, resulting in a diffraction-limited performance of the spectrometer optics. The prototype of the device has been fabricated and characterized. It takes a volume of 0.5 cm(3) and provides a FWHM spectral resolution of 0.7 nm over a 350 nm bandwidth from 420 nm to 770 nm combined with an etendue of 7.4x10(-5) mm(2) sr. PMID:19037373

Grabarnik, Semen; Emadi, Arvin; Wu, Huaiwen; de Graaf, Ger; Wolffenbuttel, Reinoud F

2008-12-01

357

Hadamard spectrometer for passive LWIR standoff surveillance  

NASA Astrophysics Data System (ADS)

Based on the principle of the Integrated Optical Spectrometer (IOSPEC), a waveguide-based, longwave infrared (LWIR) dispersive spectrometer with multiple input slits for Hadamard spectroscopy was designed and built intended for passive standoff chemical agent detection in 8 to 12?m spectral range. This prototype unit equips with a three-inch input telescope providing a field-of-view of 1.2 degrees, a 16-microslit array (each slit 60 ?m by 1.8 mm) module for Hadamard binary coding, a 2-mm core ZnS/ZnSe/ZnS slab waveguide with a 2 by 2 mm2 optical input and micro-machined integrated optical output condensor, a Si micro-machined blazing grating, a customized 128-pixel LWIR mercury-cadmium-telluride (MCT) LN2 cooled detector array, proprietary signal processing technique, software and electronics. According to the current configuration, it was estimated that the total system weight to be ~4 kg, spectral resolution <4cm-1 and Noise Equivalent Spectral Radiance (NESR) <10-8 Wcm-2 sr-1cm-1 in 8 to 12 ?m. System design and preliminary test results of some components will be presented. Upon the arrival of the MCT detector array, the prototype unit will be further tested and its performance validated in fall of 2007.

Kruzelecky, Roman V.; Wong, Brian; Zou, Jing; Mohammad, Najeeb; Jamroz, Wes; Soltani, Mohammed; Chaker, Mohamed; Haddad, Emile; Laou, Philips; Paradis, Suzanne

2007-10-01

358

Improved coupling to integrated spatial heterodyne spectrometers with applications to space  

NASA Astrophysics Data System (ADS)

Multiple Aperture Transform Chip Heterodyne (MATCH) spectrometers have been developed for targeted remote sensing applications in harsh environments. These waveguide-based Fourier Transform Spectrometers (FTS) offer significant improvements in resource efficiency over monolithic glass implementations, but are relatively limited in terms of input coupling efficiency and fill factor of the input facet. Integrated optics spectrometers have significant resource advantages for space applications. Monolithic Spatial Heterodyne Spectrometers are insensitive to vibration and do not require frequent calibration. In addition, Fourier Transform Spectrometers are known to provide significant performance advantages for emission spectroscopy. Ongoing work will improve the MATCH spectrometer input coupling efficiency from free space. This paper discusses the signal to noise improvements expected by incorporation of surface gratings, or back-thinning and stacking of slabs. We show that the use of surface gratings can increase the throughput over coupling to bare waveguides alone (in a single polarization), and provide close to 100% fill factor, albeit with limited field. Étendue improvements associated with stacked slabs are limited only by the sensing area available, but the fill factor of the input facet is limited to ~10%. The impact of these improvements is assessed in the context of two space-based applications: 1) Atmospheric remote sensing in the context of Spatial Heterodyne Observations of Water (solar occultation absorption spectroscopy) near 1.3 ?m and 2) Point emission spectroscopy (LIBS/Raman/fluorescence) for mineral identification on a planetary rover.

Scott, A.; Bock, P.; Ramos, C. A.; Lamontagne, B.; Cheben, P.; Florja?czyk, M.; Fernandez, I. M.; Janz, S.; Ortega-Monux, A.; Solheim, B.; Xu, D.-X.

2011-02-01

359

Fibre gratings for hydrogen sensing  

NASA Astrophysics Data System (ADS)

Liquid hydrogen has been intensively used in aerospace applications for the past 40 years and is of great interest for future automotive applications. Following major explosive risks due to the use of hydrogen in air, several studies were carried out in order to develop optical fibre sensors for the detection of hydrogen leakage. This paper aims at the presentation of new hydrogen sensors based on the use of fibre Bragg gratings (FBG) and long period gratings (LPG) coated by palladium nanolayers. The sensing principle based on the palladium-hydrogen interaction is presented, as well as experimental results. It is shown that both techniques could be used for hydrogen sensing but with a sensitivity enhanced by a factor up to 500 when using a LPG sensor. FBG sensors appear to be pure strain sensors and LPG sensors are mainly based on the coupling between the cladding modes and evanescent or surface plasmon waves. Preliminary results obtained with an in-fibre Mach-Zehnder interferometer configuration with in-series LPG sensors are also presented. They show potential interest to compensate for the thermal sensitivity of the fibre gratings.

Trouillet, Alain; Marin, Emmanuel; Veillas, Colette

2006-05-01

360

Regenerated draw tower grating (DTG) temperature sensors  

NASA Astrophysics Data System (ADS)

The idea of Bragg gratings, generated during the drawing process of a fiber dated back almost 20 years ago. The technical improvement of the DTG process results today in high reliable and cost effective Bragg gratings for versatile application in the optical fiber sensor market. Due to the single pulse exposure of the fiber, the gratings behave typically like type I gratings with respect to their temperature stability. This means that such gratings only work up to temperatures lower than 300 °C. To increase temperature stability we combined DTG arrays with hydrogen loading and a thermal regeneration process which enables their use in high temperature environment. The regenerated draw tower gratings are suitable for temperatures up to 900°C.

Lindner, Eric; Canning, John; Chojetzki, Christoph; Brückner, Sven; Becker, Martin; Rothhardt, Manfred; Bartelt, Hartmut

2011-05-01

361

Bragg gratings made with ultrafast radiation in crystal waveguides: lithium niobate, sapphire and YAG Bragg gratings  

NASA Astrophysics Data System (ADS)

We present results of Bragg gratings inscription in several crystalline optical weveguiding structures. Using infrared femtosecond radiation and the phase mask method, Bragg gratings were inscribed in multimode crystalline sapphire fiber, RPE lithium niobate waveguides and large area core multimode YAG fibers. It was shown that Bragg grating structures could be created in all these crystalline substrates with comparable IR- intensities. The spectral characteristics and the thermal stability of these Bragg gratings is also presented.

Grobnic, Dan; Mihailov, Stephen J.; Smelser, Christopher W.

2007-10-01

362

Polarization properties of chiral fiber gratings  

Microsoft Academic Search

Recent experiments (Kopp et al 2007 J. Opt. Soc. Am. B 24 A48) have demonstrated that the polarization sensitivity of chiral fiber gratings depends strongly on the grating symmetry: double-helix fibers are polarization sensitive while single-helix fibers are not. A coupled-mode perturbation theory is developed and used to explain the polarization properties of chiral fiber gratings. Features of the transmission

Gennady Shvets; Simeon Trendafilov; Victor I. Kopp; Daniel Neugroschl; Azriel Z. Genack

2009-01-01

363

Ronchi retarder gratings as polarization modulators  

NASA Astrophysics Data System (ADS)

We show Ronchi grating made of cellophane; this device has the particularity of modulate the polarization state of an arbitrary polarizes source. The grating period can be designed to obtain two linear perpendicular polarization states, horizontal and vertical, or circular, right and left if the source has linear or circular polarization state respectively. With this grating, we can modulate or demodulate images for stereoscopic applications.

Ortiz-Gutierrez, Mauricio; Olivares-Perez, Arturo; Perez-Cortes, Mario; Juarez-Perez, Jose L.; Pinto-Iguanero, Bernardina; Gomez-Colin, Maria R.; Ibarra-Torres, Juan Carlos

2002-05-01

364

High-efficiency multilayer dielectric diffraction gratings  

SciTech Connect

The design and performance of a new type of high-efficiency diffraction grating for use in either transmission or reflection are described. The gratings are produced in a multilayer dielectric coating deposited upon optically flat substrates. By proper design of the multilayer stack and grating structure, a diffraction efficiency in excess of 96% for polarized light in the {ital m}={minus}1 order in reflection has been achieved.

Perry, M.D.; Boyd, R.D.; Britten, J.A.; Decker, D.; Shore, B.W. [Lawrence Livermore National Laboratory, P.O. Box 808, L-493, Livermore, California 94550 (United States); Shannon, C.; Shults, E. [Hughes Electro-Optic Systems, 2000 East El Segundo Boulevard, El Segundo, California 90245 (United States)

1995-04-15

365

Dispersion-free fibre Bragg gratings  

Microsoft Academic Search

Fibre Bragg gratings with reduced\\/eliminated in-band dispersion are presented. When tested in add-drop configurations at 10 Gbit\\/s both 25 GHz and 50 GHz bandwidth gratings are shown to exhibit superior performance with no dispersion-induced penalties in the stopband. Furthermore, the demonstrated linear-phase Bragg gratings have >70% channel filling factor values and reflectivities in excess of 99.9%.

Morten Ibsen; Periklis Petropoulos; M. N. Zervas; Ricardo Feced

2001-01-01

366

Heterodyne detection for Fiber Bragg Grating sensors  

Microsoft Academic Search

In this paper, we present a Fiber-Bragg-Grating-based temperature sensor. The technique employs heterodyne detection using two Fiber Bragg Gratings. One of the gratings is used as a reference (local oscillator) and the second as a sensing arm. This sensor uses a Folded Mach-Zehnder interferometer. As the temperature changes, the Bragg wavelength of the FBG shifts. The heterodyne detection is used

H. Bellil M. A. G. Abushagur; Mustafa A. G Abushagur

2000-01-01

367

Active diffraction gratings: Development and tests  

NASA Astrophysics Data System (ADS)

We present the realization and characterization of an active spherical diffraction grating with variable radius of curvature to be used in grazing-incidence monochromators. The device consists of a bimorph deformable mirror on the top of which a diffraction grating with laminar profile is realized by UV lithography. The experimental results show that the active grating can optimize the beam focalization of visible wavelengths through its rotation and focus accommodation.

Bonora, S.; Frassetto, F.; Zanchetta, E.; Della Giustina, G.; Brusatin, G.; Poletto, L.

2012-12-01

368

Hybrid fiber Bragg grating\\/long period fiber grating sensor for strain\\/temperature discrimination  

Microsoft Academic Search

We demonstrate a novel sensor which uses the difference in strain and temperature response of fiber Bragg gratings and a long period fiber grating to discriminate between strain and temperature induced wavelength shifts. Sensor interrogation is performed entirely on the fiber Bragg grating reflection signals. Strain and temperature were simultaneously measured to ±9 ?strain and ±1.5°C over a wide range

H. J. Patrick; G. M. Williams; A. D. Kersey; J. R. Pedrazzani; A. M. Vengsarkar

1996-01-01

369

Thermal gratings and phase in high-order, transient-grating spectroscopy.  

PubMed

Thermal gratings are a well known feature in one-dimensional (i.e., single excitation) transient-grating spectroscopy. This paper presents theory and experiments for thermal gratings in multiple dimensions (i.e., with many excitations). The theory of thermal gratings is extended to an arbitrary number of dimensions using an incoherent Hilbert-space formalism. Interference between Hilbert-space pathways makes it impossible for a thermal grating to propagate across multiple time intervals. The only surviving signal is a hybrid--a population grating between excitations and a thermal grating between the final excitation and the probe. This theory is tested on auramine O in methanol (1D) and in an ionic liquid (3-butyl-1-methylimidazolium hexafluorophosphate) (1D and 2D). In methanol, the ground-state recovery and thermal-grating signals are well separated in time; in the ionic liquid, they are not. Using the results of the theory, accurate subtraction of the thermal-grating signal is possible, extending the useful time range of the experiments. Both the comparison to the theory and the subtraction of the thermal-grating signal are dependent on accurate measurements of the time-dependent phase in these systems. Models are proposed to account for the time-dependent phase. Beer's law is generalized to multidimensional grating spectroscopy. This law provides conventions for consistently comparing the absolute phases and magnitudes between grating and nongrating experiments and between experiments of differing dimensionality. PMID:21495759

Sahu, Kalyanasis; Berg, Mark A

2011-04-14

370

Submicron grating fabrication on GaAs  

NASA Astrophysics Data System (ADS)

The laboratory techniques used for the fabrication of submicron gratings in GaAs are presented. A thin (about 1250 A) film of Shipley AZ1450B photoresist on GaAs is exposed holographically with the use of the 4579 A line of argon ion laser to produce gratings with a period of approximately 0.35 micron. Data are presented that demonstrate the effects of variation of the following parameters: developer type, developer time, laser intensity, exposure time, photoresist thickness, and ion beam etching parameters. Relative grating efficiency measurements as a function of parameter variations indicate an optimum set of parameters for grating fabrication.

Heflinger, D.; Kirk, J.; Cordero, R.; Evans, G.

1981-01-01

371

Two-point source interferometric grating writing.  

PubMed

A novel grating-writing interferometer is demonstrated. This interferometer is compact, stable, and tunable well over 1000 nm and does not suffer from the inherent path-length differences that are present in other methods. It allows for high-quality gratings to be inscribed by preventing light from unwanted orders from affecting the fringe pattern. This technique is used to introduce a novel method of apodization based on removing the Fresnel end reflections in a grating. The experimental evidence proves the concept and shows that the technique is potentially useful for Bragg-grating inscription. PMID:15176203

Ashton, Brian J; Canning, John; Groothoff, Nathaniel

2004-05-20

372

Active resonant subwavelength grating devices for high speed spectroscopic sensing  

NASA Astrophysics Data System (ADS)

In this paper, we describe progress towards a multi-color spectrometer and radiometer based upon an active resonant subwavelength grating (RSG). This active RSG component acts as a tunable high-speed optical filter that allows device miniaturization and ruggedization not realizable using current sensors with conventional bulk optics. Furthermore, the geometrical characteristics of the device allow for inherently high speed operation. Because of the small critical dimensions of the RSG devices, the fabrication of these sensors can prove challenging. However, we utilize the state-of-the-art capabilities at Sandia National Laboratories to realize these subwavelength grating devices. This work also leverages previous work on passive RSG devices with greater than 98% efficiency and ~1nm FWHM. Rigorous coupled wave analysis has been utilized to design RSG devices with PLZT, PMN-PT and BaTiO3 electrooptic thin films on sapphire substrates. The simulated interdigitated electrode configuration achieves field strengths around 3×107 V/m. This translates to an increase in the refractive index of 0.05 with a 40V bias potential resulting in a 90% contrast of the modulated optical signal. We have fabricated several active RSG devices on selected electro-optic materials and we discuss the latest experimental results on these devices with variable electrostatic bias and a tunable wavelength source around 1.5?m. Finally, we present the proposed data acquisition hardware and system integration plans.

Gin, A. V.; Kemme, S. A.; Boye, R. R.; Peters, D. W.; Ihlefeld, J. F.; Briggs, R. D.; Wendt, J. R.; Marshall, L. H.; Carter, T. R.; Samora, S.

2009-02-01

373

Extremely achromatic f/1.0 all-spherical camera constructed for the high-resolution echelle spectrometer of the Keck telescope  

NASA Astrophysics Data System (ADS)

Set of designs of very fast cameras featuring very high degree of image quality and achromaticity is reported. These cameras give superb image quality over 6deg to 8deg diameter field of view over a spectral range of 0.3-1.1 micron or more. The basic design is optimizable to quite a range of pupil distances.

Epps, Harland W.; Vogt, Steven S.

1993-11-01

374

Analysis and System Design Framework for Infrared Spatial Heterodyne Spectrometers  

SciTech Connect

The authors present a preliminary analysis and design framework developed for the evaluation and optimization of infrared, Imaging Spatial Heterodyne Spectrometer (SHS) electro-optic systems. Commensurate with conventional interferometric spectrometers, SHS modeling requires an integrated analysis environment for rigorous evaluation of system error propagation due to detection process, detection noise, system motion, retrieval algorithm and calibration algorithm. The analysis tools provide for optimization of critical system parameters and components including : (1) optical aperture, f-number, and spectral transmission, (2) SHS interferometer grating and Littrow parameters, and (3) image plane requirements as well as cold shield, optical filtering, and focal-plane dimensions, pixel dimensions and quantum efficiency, (4) SHS spatial and temporal sampling parameters, and (5) retrieval and calibration algorithm issues.

Cooke, B.J.; Smith, B.W.; Laubscher, B.E.; Villeneuve, P.V.; Briles, S.D.

1999-04-05

375

The GRIFFIN spectrometer  

NASA Astrophysics Data System (ADS)

Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) is an advanced new high-efficiency ?-ray spectrometer being developed for use in decay spectroscopy experiments with low-energy radioactive ion beams provided by TRIUMF's Isotope Separator and Accelerator (ISAC-I) radioactive ion beam facility. GRIFFIN will be comprised of sixteen large-volume clover-type high-purity germanium (HPGe) ?-ray detectors coupled to custom digital signal processing electronics and used in conjunction with a suite of auxiliary detection systems. This article provides an overview of the GRIFFIN spectrometer and its expected performance characteristics.

Svensson, C. E.; Garnsworthy, A. B.

2013-10-01

376

Broad band waveguide spectrometer  

DOEpatents

A spectrometer for analyzing a sample of material utilizing a broad band source of electromagnetic radiation and a detector. The spectrometer employs a waveguide possessing an entry and an exit for the electromagnetic radiation emanating from the source. The waveguide further includes a surface between the entry and exit portions which permits interaction between the electromagnetic radiation passing through the wave guide and a sample material. A tapered portion forms a part of the entry of the wave guide and couples the electromagnetic radiation emanating from the source to the waveguide. The electromagnetic radiation passing from the exit of the waveguide is captured and directed to a detector for analysis.

Goldman, Don S. (Folsom, CA)

1995-01-01

377

The research of Raman spectra measurement system based on tiled-grating monochromator  

NASA Astrophysics Data System (ADS)

A set of Raman spectrum measurement system, essentially a Raman spectrometer, has been independently designed and accomplished by our research group. This system adopts tiled-grating structure, namely two 50mm × 50mm holographic gratings are tiled to form a big spectral grating. It not only improves the resolution but also reduces the cost. This article outlines the Raman spectroscopy system's composition structure and performance parameters. Then corresponding resolutions of the instrument under different criterions are deduced through experiments and data fitting. The result shows that the system's minimum resolution is up to 0.02nm, equivalent to 0.5cm-1 wavenumber under Rayleigh criterion; and it will be up to 0.007nm, equivalent to 0.19cm-1 wavenumber under Sparrow criterion. Then Raman spectra of CCl4 and alcohol have been obtained by the spectrometer, which agreed with the standard spectrum respectively very well. Finally, we measured the spectra of the alcohol solutions with different concentrations and extracted the intensity of characteristic peaks from smoothed spectra. Linear fitting between intensity of characteristic peaks and alcohol solution concentrations has been made. And the linear correlation coefficient is 0.96.

Liu, Li-na; Zhang, Yin-chao; Chen, Si-ying; Chen, He; Guo, Pan; Wang, Yuan

2013-09-01

378

III-Nitride grating grown on freestanding HfO2 gratings  

PubMed Central

We report here the epitaxial growth of III-nitride material on freestanding HfO2 gratings by molecular beam epitaxy. Freestanding HfO2 gratings are fabricated by combining film evaporation, electron beam lithography, and fast atom beam etching of an HfO2 film by a front-side silicon process. The 60-?m long HfO2 grating beam can sustain the stress change during the epitaxial growth of a III-nitride material. Grating structures locally change the growth condition and vary indium composition in the InGaN/GaN quantum wells and thus, the photoluminescence spectra of epitaxial III-nitride grating are tuned. Guided mode resonances are experimentally demonstrated in fabricated III-nitride gratings, opening the possibility to achieve the interaction between the excited light and the grating structure through guided mode resonance. PACS: 78.55.Cr; 81.65.Cf; 81.15.Hi.

2011-01-01

379

Integrated Bragg gratings in spiral waveguides.  

PubMed

Over the last two decades, many filters requiring custom spectral responses were obtained from photo-inscribed fiber Bragg gratings because of the flexibility inherent to this technology. However, Bragg gratings in silicon waveguides have the potential to provide faster and more efficient tuning capabilities when compared to optical fiber devices. One drawback is that Bragg gratings filters with elaborate spectral amplitude and phase responses often require a long interaction length, which is not compatible with current integration trends in CMOS compatible photonic circuits. In this paper, we propose to make Bragg gratings in spiral-shaped waveguides in order to increase their lengths while making them more compact. The approach preserves the flexibility of regular straight grating structures. More specifically, we demonstrate 2-mm long gratings wrapped in an area of 200 µm x 190 µm without any spectral degradation due to waveguide curvature. Furthermore, we interleave three spiral waveguides with integrated gratings thereby tripling the density and demonstrate good phase compensation for each of them. Finally, we show that this approach is compatible with phase-apodization of the grating coupling coefficient. PMID:23571986

Simard, Alexandre D; Painchaud, Yves; LaRochelle, Sophie

2013-04-01

380

Grating based devices in polymer optical fibre  

Microsoft Academic Search

We describe recent research into devices based on fibre Bragg gratings in polymer optical fibre. Firstly, we report on the inscription of gratings in a variety of microstructured polymer optical fibre: single mode, few moded and multimoded, as well as fibre doped with trans-4-stilbenmethanol. Secondly, we describe research into an electrically tuneable filter using a metallic coating on a polymer

H. Dobb; K. Carroll; D. J. Webb; K. Kalli; M. Komodromos; C. Themistos; G. D. Peng; A. Argyros; M. C. J. Large; M. A. van Eijkelenborg; Q. Fang; I. W. Boyd

2006-01-01

381

Inquiry with Laser Printer Diffraction Gratings  

ERIC Educational Resources Information Center

|The pages of "The Physics Teacher" have featured several clever designs for homemade diffraction gratings using a variety of materials--cloth, lithographic film, wire, compact discs, parts of aerosol spray cans, and pseudoliquids and pseudosolids. A different and inexpensive method I use to make low-resolution diffraction gratings takes advantage…

Van Hook, Stephen J.

2007-01-01

382

An Improved Diffraction Grating Spectroscope Experiment.  

ERIC Educational Resources Information Center

Discusses problems associated with standard diffraction grating experiments involving a diffraction grating, a straight meter stick, and a slit. Describes the use of a new spectroscope to overcome these problems using a curved scale to simplify calculations and help students obtain results from simple and straightforward measurements, thus giving…

Scherzer, Robert

1995-01-01

383

Features of photoinduced dynamic gratings in semiconductors  

SciTech Connect

The problem of influence of the diffusion process of nonequilibrium carriers on the efficiency of the dynamic grating photoinduced in a semiconductor material is studied theoretically and experimentally. An analytic expression is derived, which allows one to estimate the outlooks for applications of different semiconductor materials as active media for writing dynamic gratings. (nonlinear optical phenomena)

Grigor'ev, A M [Laser Technology Center Inc., St. Petersburg (Russian Federation)

2008-07-31

384

Application of MEMS blazed gratings in WDM  

NASA Astrophysics Data System (ADS)

For the shortage and limitation of ruled grating that have ghost lines and stray light because of period error and ruling irregularity, a method for making a wavelength division multiplexer (WDM) based on Micro Electro-Mechanical System (MEMS) blazed grating is proposed. The basic composition of WDM based on MEMS blazed grating is introduced according to the method. The process realizing MEMS blazed grating and means for improving diffraction efficiency are also introduced. MEMS blazed grating is numerical simulated and analyzed in laboratory virtual instrument engineering workbench (LabVIEW), the diffraction intensity distribution of blazed grating is presented, it is shown that the blazed grating, period is 2000nm and blazed angle is 20 degree, have the best division effect for light wave with wavelength about 1.55?m by the results. At the same time, the 3D layout of WDM is provided in ZEMAX, and the rays in WDM are traced also. It is indicated by the results when the channel spacing is greater than or equal to 50nm, the division effect is in evidence. It achieves the capability of Coarse Wavelength Division Multiplexing (CWDM). It is proved that MEMS blazed grating can be applied well in WDM by all the results.

Wu, Yongfeng; Yu, Honglin; Kang, Zhiping

2009-05-01

385

Dammann-grating-based optodigital position converter  

NASA Astrophysics Data System (ADS)

An optodigital position converter based on a Dammann grating is proposed. The converter is based on a diffraction grating with a high diffraction efficiency coupled with a binary encoding mask. The module permits parallel processing of a scene so that one can extract the position of a correlation peak. Compression of the information is also performed. The binary output is compatible with digital systems.

Bergeron, Alain; Gingras, Denis; Arsenault, Henri H.

1995-09-01

386

Perceived velocity of moving chromatic gratings.  

PubMed

Equiluminous red-green sine-wave gratings were drifted at a uniform rate in the bottom half of a 10-deg field. In the top half of the display was a sinusoidal-luminance grating of the same spatial frequency and 95% contrast that drifted in the opposite direction. Observers, while fixating a point in the display center, adjusted the speed of this upper comparison grating so that it appeared to match the velocity of the chromatic grating below. At low spatial frequencies, equiluminous gratings were appreciably slowed and sometimes stopped even though the individual bars of the grating could be easily resolved. The amount of slowing was proportionally greatest for gratings with slow drift rates. Blue-yellow sine-wave gratings showed similar effects. When luminance contrast was held constant, increasing chrominance modulation caused further decreases in apparent velocity, ruling out the possibility that the slowing was simply due to decreased luminance contrast. Perceived velocity appears to be a weighted average of luminance and chrominance velocity information. PMID:6470841

Cavanagh, P; Tyler, C W; Favreau, O E

1984-08-01

387

Hand Held Imaging Spectrometer  

Microsoft Academic Search

A small hand held, battery operated imaging infrared spectrometer, Sherlock, has been developed by Pacific Advanced Technology. The Sherlock spectral imaging camera has been designed for remote gas leak detection, however, the architecture of the camera is versatile enough that it can be applied to numerous other applications such as homeland security, chemical\\/biological agent detection, medical and pharmaceutical applications, as

Michele Hinnrichs

2002-01-01

388

Undergraduate Mass Spectrometer  

Microsoft Academic Search

Described here is a simple static-field mass spectrometer which has had usefulness both as an undergraduate laboratory instrument and as a piece of demonstration apparatus. The design provides for the adjustment of such parameters as magnet position, slit widths and heights, and allows the use of different types of sources and detectors. Ion currents are large enough to be easily

John W. Dewdney

1960-01-01

389

Cyclotrons as mass spectrometers  

SciTech Connect

The principles and design choices for cyclotrons as mass spectrometers are described. They are illustrated by examples of cyclotrons developed by various groups for this purpose. The use of present high energy cyclotrons for mass spectrometry is also described. 28 references, 12 figures.

Clark, D.J.

1984-04-01

390

Polymeric wavelength filters with polymer gratings  

NASA Astrophysics Data System (ADS)

Wavelength filters with Bragg gratings are demonstrated based on low-loss polymer waveguides and high-refractive-index polymer gratings. Two kinds of fluorinated polymers, perfluorocyclobutane and fluorinated poly(arylene ethers) are used for the low-loss waveguide operating around the 1.55 ?m wavelength. The polymer grating is made of Resole, and it is successfully integrated in the polymer waveguides. In order to fabricate the Bragg gratings on the polymer waveguides, we use a phase mask and a Hg lamp in a mask aligner as the illuminating source instead of the laser. This method provides uniform gratings on a large area as well as the alignment capability. In the fabricated wavelength filters, the reflectivity at the Bragg wavelength is 30 dB, the 3 dB bandwidth is as narrow as 0.6 nm, and the insertion loss is 3.7 dB.

Oh, Min-Cheol; Lee, Myung-Hyun; Ahn, Joo-Heon; Lee, Hyung-Jong; Han, Seon Gyu

1998-03-01

391

Manufacture and Development of Multilayer Diffraction Gratings  

SciTech Connect

The OMEGA EP Facility includes two high-energy, short-pulse laser beams that will be focused to high intensity in the OMEGA target chamber, providing backlighting of compressed fusion targets and investigating the fast-ignition concept. To produce 2.6 kJ output energy per beam, developments in grating compressor technology are required. Gold-coated diffraction gratings limit on-target energy because of their low damage fluence. Multilayer dielectric (MLD) gratings have shown promise as high-damage-threshold, high-efficiency diffraction gratings suitable for use in high-energy chirped-pulse amplification. This paper details the manufacture and development of these gratings, including the specifics of the MLD coating, holographic lithography, reactive ion etching, reactive ion-beam cleaning, and wet chemical cleaning.

Keck, J.; Oliver, J.B.; Kessler, T.J.; Huang, H.; Barone, J.; Hettrick, J.; Rigatti, A.L.; Hoover, T.; Marshall, K.L.; Schmid, A.W.; Kozlov, A.; Kosc, T.Z.

2006-03-01

392

Quantum theory of fibre Bragg grating solitons  

NASA Astrophysics Data System (ADS)

Following the pioneering work of Professor Haus, a general quantum theory for bi-directional nonlinear optical pulse propagation problems is developed and applied to study the quantum properties of fibre Bragg grating solitons. Fibre Bragg grating solitons are found to be automatically amplitude squeezed after passing through the grating and the squeezing ratio saturates after a certain grating length. The optimal squeezing ratio occurs when the pulse energy is slightly above the fundamental soliton energy. One can also compress the soliton pulsewidth and enhance the squeezing simultaneously by using an apodized grating, as long as the solitons evolve adiabatically. The authors would like to use this paper to express their deep thanks and respect to Professor Hermann A Haus for the inspiration they have directly or indirectly received from him.

Lee, Ray-Kuang; Lai, Yinchieh

2004-08-01

393

Nanosecond time-resolved vacuum ultraviolet spectrometer for ion diode spectroscopy  

SciTech Connect

A 1-m normal incidence spectrometer has been modified for use as a diagnostic of ion diode plasmas. To improve instrumental sensitivity, an elliptical mirror images an anode surface plasma onto the entrance slit of an [ital f]/10 normal incidence spectrometer. The detector is a time-resolving copper iodide coated microchannel plate stripline framing camera with 60-[mu]m resolution, limiting instrumental resolution to 1 A with a 600 l/mm grating in first order. Reflectivity of optics and photoelectron efficiency limit the spectral range from 400 to 2000 A. With a 600-l/mm grating the detector spans a 600-A range. Applications of the instrument may include ion source divergence measurements from Doppler broadening, electric field measurements from Stark splittings or shifts, electron temperature from mean ionization state, and magnetic field measurements on high-power [ital Z] pinches from Zeeman splitting.

Nash, T.; Noack, D.; Filuk, A.B. (Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States))

1993-09-01

394

Sounding rocket program aeronomy. Upper Polar Atmosphere Project. Measurements by the infrared spectrometer AB 3  

NASA Astrophysics Data System (ADS)

A rocket-borne grating spectrometer system for measuring the fine structure of the 63 micron atomic oxygen transition is described. Thermodynamic equilibria and water vapor concentrations can be determined from these measurements. The system employs an Ebert-Fastie spectrometer. The low signal-to-noise ratio associated with the very low intensities studied led to the use of He cooling. A chopper filter system with ac amplification was employed. Intensity profile measurements lead to the conclusion that fine structure atomic oxygen levels are not in local thermodynamic equilibrium throughout the thermosphere. Upper limits of the lower thermosphere water vapor concentrations are deduced from the measured intensities

Grossmann, K. U.; Offerman, D.; Scheer, J.

1980-06-01

395

APEX/J-PEX: A High-Resolution Spectrometer for EUV/X-ray Wavelengths  

NASA Astrophysics Data System (ADS)

Future X-ray and EUV missions should include high-resolution spectrometers, permitting use of the full range of spectroscopic diagnostics, in particular measurement of line profiles and Doppler shifts. We present a design for such an instrument (APEX), which would fly on a Small Explorer Satellite and which employs multilayer-coated ion-etched gratings in a normal-incidence configuration. We have already flown successfully a prototype spectrometer (J-PEX) on a NASA sounding rocket. The resulting EUV spectrum of the white dwarf G191-B2B will be presented.

Kowalski, M. P.; Cruddace, R. G.; Gursky, H.; Yentis, D. J.

2001-09-01

396

Advanced integrated spectrometer designs for miniaturized optical coherence tomography systems  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT) has enabled clinical applications that revolutionized in vivo medical diagnostics. Nevertheless, its current limitations owing to cost, size, complexity, and the need for accurate alignment must be overcome by radically novel approaches. Exploiting integrated optics, the central components of a spectral-domain OCT (SD-OCT) system can be integrated on a chip. Arrayed-waveguide grating (AWG) spectrometers with their high spectral resolution and compactness are excellent candidates for on-chip SD-OCT systems. However, specific design-related issues of AWG spectrometers limit the performance of on-chip SD-OCT systems. Here we present advanced AWG designs which could overcome the limitations arising from free spectral range, polarization dependency, and curved focal plane of the AWG spectrometers. Using these advanced AWG designs in an SD-OCT system can provide not only better overall performance but also some unique aspects that a commercial system does not have. Additionally, a partially integrated OCT system comprising an AWG spectrometer and an integrated beam splitter, as well as the in vivo imaging using this system are demonstrated.

Akca, B. I.; Považay, B.; Chang, L.; Alex, A.; Wörhoff, K.; de Ridder, R. M.; Drexler, W.; Pollnau, M.

2013-06-01

397

Scatterometry measurement of asymmetric gratings  

NASA Astrophysics Data System (ADS)

Scatterometry has been used extensively for the characterization of critical dimensions (CD) and detailed sidewall profiles of periodic structures in microelectronics fabrication processes. So far the majority of applications are for symmetric gratings. In most cases devices are designed to be symmetric although errors could occur during fabrication process and result in undesired asymmetry. The problem with conventional optical scatterometry techniques lies in the lack of capability to distinguish between left and right asymmetries. In this work we investigate the possibility of measuring grating asymmetry using Mueller matrix spectroscopic ellipsometry (MM-SE). A patterned hard disk prepared by nano-imprint technique is used for the study. The relief image on the disk sometimes has asymmetrical sidewall profile, presumably due to the uneven separation of the template from the disk. The undesired tilting resist profile causes difficulties to the downstream processes or even makes them fail. Cross-section SEM reveals that the asymmetrical resist lines are typically tilted towards the outer diameter direction. The simulation and experimental data show that certain Mueller matrix elements are proportional to the direction and amplitude of profile asymmetry, providing a direct indication to the sidewall tilting. The tilting parameter can be extracted using rigorous optical critical dimension (OCD) modeling or calibration method. We demonstrate that this technique has good sensitivity for measuring and distinguishing left and right asymmetry caused by sidewall tilting, and can therefore be used for monitoring processes, such as lithography and etch processing, for which symmetric structures are desired.

Li, Jie; Hwu, Justin J.; Liu, Yongdong; Rabello, Silvio; Liu, Zhuan; Hu, Jiangtao

2009-12-01

398

FIRE: a near-infrared cross-dispersed echellette spectrometer for the Magellan telescopes  

Microsoft Academic Search

FIRE (the Folded-port InfraRed Echellette) is a prism cross-dispersed infrared spectrometer, designed to deliver singleobject R=6000 spectra over the 0.8-2.5 micron range, simultaneously. It will be installed at one of the auxiliary Nasmyth foci of the Magellan 6.5-meter telescopes. FIRE employs a network of ZnSe and Infrasil prisms, coupled with an R1 reflection grating, to image 21 diffraction orders onto

Robert A. Simcoe; Adam J. Burgasser; Rebecca A. Bernstein; Bruce C. Bigelow; Jason Fishner; William J. Forrest; Craig McMurtry; Judith L. Pipher; Paul L. Schechter; Matthew Smith

2008-01-01

399

FIBRE: A Broadband Submillimeter Spectrometer using Transition Edge Sensor Bolometers with SQUID multiplexer readout  

Microsoft Academic Search

FIBRE is a submillimeter spectrometer based on a helium-cooled scanning Fabry-Perot and superconducting transition edge sensor bolometers (TES). A SQUID multiplexer is used to read out the individual detector pixels. The Fabry-Perot uses a low resolution grating to order sort the incoming light. A linear bolometer array consisting of 16 elements detects this dispersed light, capturing 5 orders simultaneously from

J. Staguhn; D. J. Benford; S. A. Khan; B. Maffei; S. H. Moseley; F. Pajot; T. G. Phillips; C. Rioux; R. A. Shafer

2001-01-01

400

Design of a High Resolution X-ray Reflection Grating Demonstration  

NASA Astrophysics Data System (ADS)

The International X-ray Observatory (IXO) has baselined a soft x-ray grating spectrometer as part of its instrument complement to provide spectral resolution (R) of >1250 over the 0.3 - 1 keV band. Current generations of reflection gratings have demonstrated R of a few hundred with very small telescopes. The same basic technology can be used with a higher resolution telescope such as IXO to provide R of up to 3000 with only small modifications. We have developed a test article which will be placed in the X-ray beamline facility at GSFC using a mirror pair developed as a technology demonstration for IXO. The test article will demonstrate the current baseline requirement for resolution. We present test data (as available) and performance predictions, as well as an approach to get to R 3000, well in excess of IXO requirements.

Johnson, Tim; Casement, S.; Henderson, D.; McEntaffer, R.; Cash, W.

2009-01-01

401

Alpha Magnetic Spectrometer  

NASA Astrophysics Data System (ADS)

The Alpha Magnetic Spectrometer (AMS) is a precision particle physics magnetic spectrometer designed to measure electrons, positrons, gamma rays and various nuclei and anti-nuclei from the cosmos up to TeV energy ranges. AMS weighs 7.5 tons and measures 5 meters by 4 meters by 3 meters. It contains 300,000 channels of electronics and 650 onboard microprocessors. It was delivered to the International Space Station onboard space shuttle Endeavour and installed on May 19, 2011. Since that time, more than 14 billion cosmic ray events have been collected. All the detectors function properly. At this moment, we are actively engaged in data analysis. AMS is an international collaboration involving 16 countries and 60 institutes. It took 16 years to construct and test. AMS is the only major physical science experiment on the International Space Station and will continue to collect data over the entire lifetime of the Space Station (10-20 years).

Ting, Samuel

2012-07-01

402

FAST NEUTRON SPECTROMETER  

DOEpatents

An improved proton recoil spectrometer for determining the energy spectrum of a fast neutron beam is described. Instead of discriminating against and thereby"throwing away" the many recoil protons other than those traveling parallel to the neutron beam axis as do conventional spectrometers, this device utilizes protons scattered over a very wide solid angle. An ovoidal gas-filled recoil chamber is coated on the inside with a scintillator. The ovoidal shape of the sensitive portion of the wall defining the chamber conforms to the envelope of the range of the proton recoils from the radiator disposed within the chamber. A photomultiplier monitors the output of the scintillator, and a counter counts the pulses caused by protons of energy just sufficient to reach the scintillator.

Davis, F.J.; Hurst, G.S.; Reinhardt, P.W.

1959-08-18

403

Blazed grating fabrication through gray-scale Xray lithography  

Microsoft Academic Search

Blazed gratings have been fabricated using gray-scale X-ray lithography. The gratings have high efficiency, low parasitic light, and high groove quality. The fabrication technique and resist characterization are described. The gratings can be generated over a considerable range of distances from the X-ray mask, thus demonstrating the ability to write gratings on a substrate of effectively arbitrary shape.

Pantazis Mouroulis; Frank T. Hartley; Daniel W. Wilson; Victor E. White; Aidan Shori; Steven Nguyen; Min Zhang; Martin Feldman

2003-01-01

404

Method of Eigenvectors for Numerical Studies of Multilayer Gratings  

Microsoft Academic Search

A new approach to numerical studies of lamellar multilayer gratings is developed. It stands out against the existing modal and differential methods by its applicability to thick multilayer gratings with a small grating period, and also to the case of grazing incidence of radiation. The diffraction properties of multilayer gratings are calculated for x rays with the angles of incidence

V. I. Erofeev; N. V. Kovalenko

1997-01-01

405

X-ray diffraction from epitaxial multilayered surface gratings  

Microsoft Academic Search

X-ray diffraction from simple monocrystalline and epitaxial multilayered surface gratings will be described theoretically by use of a distorted wave Born approximation of second order. The intensity patterns of simple and multilayered gratings have been simulated by this treatment and compared with the kinematical approximation. The gratings act simultaneously as reflection and transmission gratings. This gives rise to Umweganregung also

G. T. Baumbach; M. Gailhanou

1995-01-01

406

Numerical studies of multilayer gratings using the method of eigenvectors  

Microsoft Academic Search

The method of eigenvectors has been adapted for numerical studies of lamellar multilayer gratings with a partially etched multilayer stack (phase multilayer gratings). Unlike the existing modal and differential methods, this method can be applied to thick multilayer gratings with a small grating period, and also to the case of grazing incidence of radiation. For the case of soft X-rays,

V. I. Erofeev; N. V. Kovalenko

1998-01-01

407

Achromatic waveguide coupling with a hybrid grating-mirror  

NASA Astrophysics Data System (ADS)

A new grating coupler that incorporates a hybrid grating-mirror is proposed. An analysis of the device indicates that it has a much larger achromatic range than that of conventional grating couplers, as well as a relaxed fabrication requirement for the grating.

Huang, Qiang; Ashley, Paul R.

1996-07-01

408

Electron volt neutron spectrometers  

Microsoft Academic Search

The advent of pulsed neutron sources has made available intense fluxes of epithermal neutrons (500 meV ?E?100 eV ). The possibility to open new investigations on condensed matter with eV neutron scattering techniques, is related to the development of methods, concepts and devices that drive, or are inspired by, emerging studies at this energy scale. Electron volt spectrometers have undergone continuous improvements

A. Pietropaolo; R. Senesi

2011-01-01

409

An imaging neutron spectrometer  

Microsoft Academic Search

We have developed, fabricated and tested a prototype imaging neutron spectrometer designed for real-time neutron source location and identification. Real-time detection and identification is important for locating materials. These materials, specifically uranium and transuranics, emit neutrons via spontaneous or induced fission. Unlike other forms of radiation (e.g. gamma rays), penetrating neutron emission is very uncommon. The instrument detects these neutrons,

J. M. Ryan; C. Bancroft; P. Bloser; U. Bravar; C. Frost; M. L. McConnell; J. Legere; J. Wood; R. Woolf; D. Fourguette; L. Larocque; J. Pavlich; G. Ritter; G. Wassick

2010-01-01

410

An active spectrometer  

SciTech Connect

This article describes a new type of correlation spectrometer, dubbed an {open_quotes}active spectrometer.{close_quotes} It utilizes an oscillating mirror in a 1/4-m-Rowland circle spectrometer configuration to displace the spectrum periodically in the dispersion direction relative to fixed exit slits. The wavelength of the light passing through each slit is modulated sinusoidally at the mechanical oscillation frequency and its intensity is measured with a spot detector such as a photomultiplier or photodiode. With a PC-based control/data acquisition system, the signal from each detector is sampled digitally at a frequency constrained to be an integral multiple of the mirror drive frequency. From the resultant phase locking between the signal sampling and the mirror oscillation, it follows that the correlation function between the signal and mirror phase angle is obtained simply by averaging the data from successive mirror scans. Such a scan-averaged spectrum with low noise may then be compared with digitally stored reference spectra obtained through the same instrument. ac coupling of detector and amplifier results in rejection of continuum light and, when photodiodes are used as detectors, the maximization of preamplifier gain. {copyright} {ital 1999 American Institute of Physics.}

Brooks, N.H. [General Atomics, San Diego, California 92186-9784 (United States); Finkenthal, D.F. [Palomar College, San Marcos, California 92069 (United States); Jensen, T.H. [General Atomics, San Diego, California 92186-9784 (United States); Naumenko, N.N. [Institute of Molecular and Atomic Physics, 220072 Minsk (Belarus); Tugarinov, S.N. [TRINITI Lab, 142092 Troitsk (Russia)

1999-02-01

411

An active spectrometer  

NASA Astrophysics Data System (ADS)

This article describes a new type of correlation spectrometer, dubbed an ``active spectrometer.'' It utilizes an oscillating mirror in a 1/4-m-Rowland circle spectrometer configuration to displace the spectrum periodically in the dispersion direction relative to fixed exit slits. The wavelength of the light passing through each slit is modulated sinusoidally at the mechanical oscillation frequency and its intensity is measured with a spot detector such as a photomultiplier or photodiode. With a PC-based control/data acquisition system, the signal from each detector is sampled digitally at a frequency constrained to be an integral multiple of the mirror drive frequency. From the resultant phase locking between the signal sampling and the mirror oscillation, it follows that the correlation function between the signal and mirror phase angle is obtained simply by averaging the data from successive mirror scans. Such a scan-averaged spectrum with low noise may then be compared with digitally stored reference spectra obtained through the same instrument. ac coupling of detector and amplifier results in rejection of continuum light and, when photodiodes are used as detectors, the maximization of preamplifier gain.

Brooks, N. H.; Finkenthal, D. F.; Jensen, T. H.; Naumenko, N. N.; Tugarinov, S. N.

1999-02-01

412

A versatile three\\/four crystal X-ray spectrometer\\/scatterometer for X-ray optical elements Performance and applications  

Microsoft Academic Search

A versatile X-ray spectrometer\\/scatterometer for the study of X-ray optical elements, such as grazing incidence mirrors, crystals and X-ray gratings, has been built and put into operation at the Danish Space Research Institute. The spectrometer is built on a 1.5 m long granite bench with the X-ray source located at one end of the bench where it can be rotated

F. E. Christensen; E. Jacobsen; P. Jonasson; M. M. Madsen; H. W. Schnopper

1986-01-01

413

Large size metallic glass gratings by embossing  

NASA Astrophysics Data System (ADS)

Bulk metallic glasses have excellent thermoforming ability in their wide supercooled liquid region. We show that large-size metallic glass grating (~8 × 8 mm2) with fine periodicity and ultra smooth surface feature can be readily fabricated by hot embossing. The method for fabrication of gratings is proved to be much cheaper, and requires low pressure and short time (less than 30 s). The metallic glass gratings exhibit comparable optical properties such as rainbow-like spectrum when shone by fluorescent lamp light.

Ma, J.; Yi, J.; Zhao, D. Q.; Pan, M. X.; Wang, W. H.

2012-09-01

414

Feeling grateful: a parse research method study.  

PubMed

The author in this article reports a Parse research method study on the universal experience of feeling grateful with 10 participants living in community. The central finding of this study is the structure: The living experience of feeling grateful is potent elation amid tribulation arises with the assuredness-unassuredness of benevolent alliances. The findings are discussed in relation to the humanbecoming school of thought and related literature. New knowledge generated from this study: (a) explicates unique ways of becoming related to feeling grateful, (b) enhances understanding of ways of connecting with persons in practice, and (c) reveals phenomena for further research. PMID:23575493

Hart, Judith D

2013-04-01

415

Aplanatic and quasi-aplanatic diffraction gratings  

DOEpatents

A reflection diffraction grating having a series of transverse minute grooves of progressively varying spacing along a concave surface enables use of such gratings for X-ray or longer wavelength imaging of objects. The variable groove spacing establishes aplanatism or substantially uniform magnification across the optical aperture. The grating may be used, for example, in X-ray microscopes or telescopes of the imaging type and in X-ray microprobes. Increased spatial resolution and field of view may be realized in X-ray imaging.

Hettrick, Michael C. (Berkeley, CA)

1989-01-01

416

Aplanatic and quasi-aplanatic diffraction gratings  

DOEpatents

A reflection diffraction grating having a series of transverse minute grooves of progressively varying spacing along a concave surface enables use of such gratings for x-ray or longer wavelength imaging of objects. The variable groove spacing establishes aplanatism or substantially uniform magnetification across the optical aperture. The grating may be sued, for example, in x-ray microscopes or telescopes of the imaging type and in x-ray microprobed. Increased spatial resolution and field of view may be realized in x-ray imaging. 5 figs.

Hettrick, M.C.

1987-09-14

417

Formation of holographic diffraction gratings in photoresist  

NASA Astrophysics Data System (ADS)

The exposure-development process for the fabrication of holographic diffraction gratings for integrated optics in the positive photoresist Shipley AZ-1350 is theoretically and experimentally investigated. An analysis of the light intensity distribution is carried out, taking into account the reflectivity at the photoresist-substrate interface and the attenuation in the photoresist for two holographic exposure arrangements. The influence of the exposure energy, the development time for a fixed concentration of the developer and the initial photoresist thickness are described. Various grating profiles are calculated for photoresist films, coated on matched and reflective substrates. Scanning electron micrographs demonstrate very good agreement between the actual and calculated gratings profiles.

Mashev, L.; Tonchev, S.

1981-11-01

418

Production of diffraction gratings using holographic interferometry  

NASA Astrophysics Data System (ADS)

Holographic transmission gratings are produced using low power He-Ne laser and the 488-nm Ar-ion laser line. From the observed data of the Hg spectrum and the 488.0-nm, 514.5-nm and 632.8-nm laser lines the fringe spacings of the gratings are calculated. Using the gratings produced with the He-Ne laser the Rydberg constant is determined by measuring the diffraction angles of the Balmer series in the H-atomic spectrum.

Ecevit, F. N.; Guven, H.; Aydin, R.

1989-09-01

419

Fiber Bragg Grating Sensors for Harsh Environments  

PubMed Central

Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

Mihailov, Stephen J.

2012-01-01

420

Submicrometer gratings for solar energy applications.  

PubMed

Diffractive optical structures for increasing the efficiency of crystalline silicon solar cells are discussed. As a consequence of the indirect band gap, light absorption becomes very ineffective near the band edge. This can be remedied by use of optimized diffraction gratings that lead to light trapping. We present blazed gratings that increase the optically effective cell thickness by approximately a factor of 5. In addition we present a wideband antireflection structure for glass that consists of a diffraction grating with a dielectric overcoat, which leads to an average reflection of less than 0.6% in the wavelength range between 300 and 2100 nm. PMID:21052383

Heine, C; Morf, R H

1995-05-10

421

Holographically generated twisted nematic liquid crystal gratings  

SciTech Connect

A reflection holographic method is introduced to fabricate an electro-optically tunable twisted nematic (TN) liquid crystal (LC) grating, forgoing the geometrical drawing. The photoisomerization process occurring on the LC alignment layers of an LC cell in the reflection holographic configuration gives a control over the twist angle, and the grating spacing is determined by the slant angle of reflection holographic configuration. The resulting diffraction grating is in a structure of a reverse TN LC, permitting a polarization-independent diffraction efficiency. The electro-optic tunability of the diffraction efficiency is also demonstrated.

Choi, Hyunhee; Wu, J.W.; Chang, Hye Jeong; Park, Byoungchoo [Department of Physics, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Department of Electrophysics, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

2006-01-09

422

Speed enhancement in VCSELs employing grating mirrors  

NASA Astrophysics Data System (ADS)

In recent years, various approaches to improve the speed of directly modulated vertical-cavity surface-emitting lasers (VCSELs) have been reported and demonstrated good improvement. In this paper, we propose and numerically investigate a new possibility of using high-index-contrast grating (HCG) as mirror for VCSELs. By changing the grating design, one can control the reflection delay of the grating mirror, enabling the control of cavity photon lifetime. On the other hand, short energy penetration depth of the HCG results in smaller modal volume, compared to DBR VCSELs. An example structure shows that the HCG VCSEL has a 30-% higher 3-dB bandwidth than the DBR VCSEL.

Chung, Il-Sug; Mørk, Jesper

2013-03-01

423

The Mark 2 Spatial Heterodyne Spectrometer, An All Reflection, Broadband SHS  

NASA Astrophysics Data System (ADS)

First operation of an all-reflection, broadband, Spatial Heterodyne Spectrometer (SHS) is reported. This Mark 2 SHS is constructed using a custom diffraction grating and other standard optical components. The custom grating is coarse (18 grooves/mm) with a symmetric blaze. It serves as a beam splitter and beam combiner of the Mark 2 SHS. The grating is combined with a plane mirror and a roof mirror to form a very stable ring interferometer which has been used successfully in earlier narrowband SHS designs. Fringes from the extra grating orders in the main blaze envelope are unexpectedly found to combine constructively with the desired primary fringes of the interferometer. Ambiguity between wavelengths above and below blaze in a given order, and order separation are demonstrated using cross tilt of the gratings to produce diagonal fringes. Coverage of a factor of four in wavelength in a single CCD frame is demonstrated. Other performance parameters and sample data are also presented. This research is supported under NASA Grant NNX08AQ09G.

Lawler, James E.; Corliss, J.; Roesler, F. L.; Harlander, J. M.; Harris, W. M.

2010-01-01

424

Long-period fiber gratings spontaneously written by a mechanism markedly different from Hill grating formation  

NASA Astrophysics Data System (ADS)

Pumping a nonlinear germanosilicate fiber with intense near-infrared femtosecond laser pulses for supercontinuum generation may invoke multiphoton-assisted photosensitivity of glasses to write a long-period fiber grating. In sharp contrast to the spontaneous formation of a Hill grating that resonates with the writing wavelength through first-order diffraction, the long-period fiber grating resonates with the writing wavelength through second-order diffraction. This finding highlights the surprising light-matter interaction in a waveguide.

Tu, H.; Shin, S.; John, R.; Boppart, S. A.

2010-09-01

425

High-resolution imaging spectrometer for recording absolutely calibrated far ultraviolet spectra from laser-produced plasmas  

SciTech Connect

An imaging spectrometer was designed and fabricated for recording far ultraviolet spectra from laser-produced plasmas with wavelengths as short as 155 nm. The spectrometer implements a Cassegrain telescope and two gratings in a tandem Wadsworth optical configuration that provides diffraction limited resolution. Spectral images were recorded from plasmas produced by the irradiation of various target materials by intense KrF laser radiation with 248 nm wavelength. Two pairs of high-resolution gratings can be selected for the coverage of two wavebands, one grating pair with 1800 grooves/mm and covering approximately 155-175 nm and another grating pair with 1200 grooves/mm covering 230-260 nm. The latter waveband includes the 248 nm KrF laser wavelength, and the former waveband includes the wavelength of the two-plasmon decay instability at (2/3) the KrF laser wavelength (165 nm). The detection media consist of a complementary metal oxide semiconductor imager, photostimulable phosphor image plates, and a linear array of 1 mm{sup 2} square silicon photodiodes with 0.4 ns rise time. The telescope mirrors, spectrometer gratings, and 1 mm{sup 2} photodiode were calibrated using synchrotron radiation, and this enables the measurement of the absolute emission from the laser-produced plasmas with temporal, spatial, and spectral resolutions. The spectrometer is capable of measuring absolute spectral emissions at 165 nm wavelength as small as 5x10{sup -7} J/nm from a plasma source area of 0.37 mm{sup 2} and with 0.4 ns time resolution.

Brown, Charles M.; Seely, John F. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Feldman, Uri [ARTEP Inc., Ellicott City, Maryland 21042 (United States); Holland, Glenn E. [SFA Inc., 2200 Defense Highway, Suite 405, Crofton, Maryland 21114 (United States); Weaver, James L.; Obenschain, Steven P. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kjornrattanawanich, Benjawan [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA and Universities Space Research Associates, Columbia, Maryland 21044 (United States); Fielding, Drew [Commonwealth Technologies Inc., 5775 Barclay Drive, Alexandria, Virginia 22315 (United States)

2008-10-15

426

Compact spectrometer for on-line photon diagnostics at FLASH  

NASA Astrophysics Data System (ADS)

We present the design and characterization of a compact and portable spectrometer that has been realized to analyze in real time the high-order harmonic contents of the free-electron-laser beam at FLASH in Hamburg. The spectrometer can be installed at the end of any of the broad-band FEL beamlines at FLASH, to monitor in the single-shot operation the emissions of the fundamental FEL and the high-order harmonic content. The design is compact in order to obtain a portable instrument within a total envelope of less than one meter. It is based on the use of two flat-field grazing-incidence gratings and a EUV-enhanced CCD detector to cover the spectral range 1.7-40 nm (720-30 eV). The absolute response of the spectrometer, i.e. grating and detector efficiency, has been measured in the whole spectral region of operation. This allows to make calibrated measurements of the photon flux. Furthermore, the use of a bidimensional detector allows to measure also the angular divergence of the FEL beam in the direction parallel to the entrance slit. We present some experimental data of the FEL emissions taken at the beamline BL1 at FLASH. The high-order harmonic emissions have been characterized in terms of photon flux, temporal fluctuations and angular divergence. Measurements of the harmonics up to the 5th order at 3.8 nm have been done with the fundamental tuned at 19 nm. Measurements of the harmonics up to the 3rd order at 2.3 nm have been done with the fundamental tuned at 6.8 nm.

Frassetto, Fabio; Dziarzhytski, Siarhei; Guerassimova, Natalia; Poletto, Luca

2013-03-01

427

Application of terahertz spectroscopy to the characterization of biological samples using birefringence silicon grating  

NASA Astrophysics Data System (ADS)

We present a device and method for performing vector transmission spectroscopy on biological specimens at terahertz (THz) frequencies. The device consists of artificial dielectric birefringence obtained from silicon microfluidic grating structures. The device can measure the complex dielectric function of a liquid, across a wide THz band of 2 to 5.5 THz, using a Fourier transform infrared spectrometer. Measurement data from a range of liquid specimens, including sucrose, salmon deoxyribonucleic acid (DNA), herring DNA, and bovine serum albumin protein solution in water are presented. The specimen handling is simple, using a microfluidic channel. The transmission through the device is improved significantly and thus the measurement accuracy and bandwidth are increased.

Saha, Shimul C.; Grant, James P.; Ma, Yong; Khalid, Ata; Hong, Feng; Cumming, David R. S.

2012-06-01

428

Steel Grating Cage Provides Secure Enclosure.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. Certain standard commercial steel grating panels, 2 by 10 feet, can provide significant resistance to hand and power tool forced entry attacks when properly assemble...

1984-01-01

429

Microfluidic droplet grating for reconfigurable optical diffraction.  

PubMed

This Letter presents a reconfigurable optical diffraction grating using multiphase droplets on a microfluidic chip. The uniform and evenly spaced circular droplets are generated by continuously dispersing two immiscible liquids into a T junction to produce plugs, which are then transformed into a circular shape at a sudden expansion of the microchannel. In experiments, the droplet grating shows a detection limit of ~6.3x10(-5) when used as an opto fl uidic refractometer and produces different colors as a color filter. Such a grating has the advantages of high stability and wide tunability in droplet size, grating period, and refractive index, making it promising for biochemical and biomaterial applications. PMID:20517452

Yu, J Q; Yang, Y; Liu, A Q; Chin, L K; Zhang, X M

2010-06-01

430

Lens centering by using binary phase grating  

NASA Astrophysics Data System (ADS)

By using a binary phase grating, a lens centering system is constructed. In our system, the lens under alignment is mounted on a suitable mechanical axis that can be a spindle of precision lathe. A binary phase grating is used as a beam splitter. Laser beam after passing through the grating only +/- 1 orders are kept unstop, reflected back by lens surface, recombined by the same grating, and very good contrast interference fringes can be attained. When the lens together with the spindle is rotated, the interference fringes remain motionless only when the lens rotates around its axis of symmetry. If the lens rotates around an axis of asymmetry, the fringes will move. A CCD camera is used to monitor the fringes and transversal error less than a micrometer can be achieved. The interference fringes are very insensitive to vibration and environment. I the paper the theory are presented and the experimental results are given.

Lu, Zhenwu; Weng, Zhicheng

2000-10-01

431

The resonant III-nitride grating reflector  

NASA Astrophysics Data System (ADS)

We report here on the fabrication of a guided-mode resonant III-nitride grating reflector on a silicon substrate. In addition to compensating the residual stress of III-nitride layers, hafnium oxide (HfO2) film also serves as a hard mask during inductively coupled plasma reactive ion etching of III-nitride layers. The silicon substrate underneath the III-nitride gratings is etched and thus the III-nitride gratings are released and freely suspended with air as low refractive index materials on the top and bottom. The guided-mode resonances that are affected by the grating period, duty ratio, polarization and effective refractive index are experimentally characterized in the reflectance measurements. These works open the possibility of fabricating resonant III-nitride structures on the silicon substrate for further tunable III-nitride optical devices and integrated optics.

Wang, Yongjin; Wu, Tong; Tanae, Takuma; Zhu, Hongbo; Hane, Kazuhiro

2011-10-01

432

Photoinduced diffraction grating in hybrid artificial molecule.  

PubMed

Photoinduced diffraction grating is theoretically investigated in a three-level ladder-type hybrid artificial molecule comprised of a semiconductor quantum dot (SQD) and a metal nanoparticle (MNP). The SQD and the MNP are coupled via the Coulomb interaction. The probe absorption vanishes under the action of a strong coupling field, indicating an effect of electromagnetically induced transparency (EIT). Based on this EIT effect, diffraction grating is achievable when a standing-wave coupling field is applied. It turns out that the efficiency of diffraction grating is greatly improved due to the existence of the MNP. Furthermore, the diffraction efficiency can be controlled by tuning the interaction strength between the SQD and the MNP. Nearly pure phase grating is obtained, showing high transmissivity and high diffraction efficiency up to 33%. PMID:22274466

Xiao, Zhi-Hong; Zheng, Li; Lin, HongZhen

2012-01-16

433

The X-ray diffraction grating  

Microsoft Academic Search

Grazing incidence diffraction performance and imagery are discussed, with special reference to corrected systems. Throughout the period 1930-1970 the principal aim of X-ray grating research centered on the problem of the optimum groove profile and its practical realization. This was due to the fact that, unlike their optical or UV counterparts, X-ray gratings rarely diffracted more than a percent or

R. J. Speer

1976-01-01

434

Wideband plasmonic beam steering in metal gratings.  

PubMed

We demonstrate controllable light deflection in thick metal gratings with periodic subwavelength slits filled with an active material. Under specific illumination conditions, the grating becomes nearly transparent and acts as a uniform optical phased-array antenna where the phase of the radiating elements is controlled by modifying the index of refraction of the material that fills each slit. The beam-steering operational regime occurs in a wide wavelength band, and it is relatively insensitive to the input angle. PMID:22854490

de Ceglia, Domenico; Vincenti, Maria Antonietta; Scalora, Michael

2012-01-15

435

Power efficient tunable fiber grating laser  

Microsoft Academic Search

We have experimentally demonstrated that a fibre grating laser which can be repeatedly tuned within a range of 12nm by applying up to 61W electrical power to a platinum-coated output coupling fibre Bragg grating. This tuning technique demonstrates the feasibility of a compact and power efficient tunable source which is suitable for use in multi-channel DWDM systems. In addition, we

W. H. Chung; H. Y. Tam; M. S. Demokan; W. S. Man; S. Y. Liu; N. Chong

2001-01-01

436

Large N x N waveguide grating routers  

Microsoft Academic Search

We show how the grating diffraction properties of a N×N waveguide grating router (WGR) can limit the size of N when the device operates with a unique set of N wavelengths as a strict-sense nonblocking N×N cross connect. We motivate why for large N, the N optical channels should be chosen equally spaced in wavelength and not in frequency. Two

P. Bernasconi; C. Doerr; C. Dragone; M. Cappuzzo; E. Laskowski; A. Paunescu

2000-01-01

437

Grating enhanced solid-state laser amplifiers  

SciTech Connect

A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. Such an invention, as disclosed herein, uses diffraction gratings to increase gain, stored energy density, and pumping efficiency of solid-state laser gain media, such as, but not limited to rods, disks and slabs. By coupling predetermined gratings to solid-state gain media, such as crystal or ceramic laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

Erlandson, Alvin C. (Livermore, CA); Britten, Jerald A. (Clayton, CA)

2010-11-09

438

Reflection of neutrons from an optical grating  

Microsoft Academic Search

Specular and off-specular neutron intensities were measured at grazing incidence from an optical grating. The periodicity of the grating was determined from the locations of the intensity peaks in the off-specular data. An analysis of the widths of the off-specular intensity peaks showed that the effect of the coherence length of the neutron beam on the determination of a surface

Alan E. Munter; S. Adenwalla; G. F. Felcher; X. L. Zhou

1994-01-01

439

Nonlinear switching in fibre Bragg gratings.  

PubMed

We report on our recent experiments on nonlinear switching in fibre Bragg gratings. Using an all-fibre source we show an increase in transmission of a FBG from 4% to 40% at high powers. This switching is associated with the formation of gap solitons inside the grating. We also demonstrate an all-optical AND gate using polarization coupled gap solitons and the optical pushbroom. PMID:19384393

Broderick, N; Taverner, D; Richardson, D

1998-11-23

440

Submicrometer gratings for solar energy applications  

NASA Astrophysics Data System (ADS)

The paper discusses diffractive optical structures for increasing the efficiency of crystalline silicon solar cells. The use of optimized diffraction gratings that lead to light trapping to remedy the ineffective light absorption near band edges are presented. Also discussed is a wideband antireflection structure for glass that consists of diffraction grating with a dielectric overcoat, which leads to an average reflection of less then 0.6% in the wavelength range between 300 and 2100nm.

Heine, Claus; Morf, Rudolf H.

1995-05-01

441

Grism and immersion grating for space telescope  

NASA Astrophysics Data System (ADS)

The grism is a versatile dispersion element for an astronomical instrument ranging from ultraviolet to infrared. Major benefit of using a grism in a space application, instead of a reflection grating, is the size reduction of optical system because collimator and following optical elements could locate near by the grism. The surface relief (SR) grism is consisted a transmission grating and a prism, vertex angle of which is adjusted to redirect the diffracted beam straight along the direct vision direction at a specific order and wavelength. The volume phase holographic (VPH) grism consists a thick VPH grating sandwiched between two prisms, as specific order and wavelength is aligned the direct vision direction. The VPH grating inheres ideal diffraction efficiency on a higher dispersion application. On the other hand, the SR grating could achieve high diffraction efficiency on a lower dispersion application. Five grisms among eleven for the Faint Object Camera And Spectrograph (FOCAS) of the 8.2m Subaru Telescope with the resolving power from 250 to 3,000 are SR grisms fabricated by a replication method. Six additional grisms of FOCAS with the resolving power from 3,000 to 7,000 are VPH grisms. We propose "Quasi-Bragg grism" for a high dispersion spectroscopy with wide wavelength range. The germanium immersion grating for instance could reduce 1/64 as the total volume of a spectrograph with a conventional reflection grating since refractive index of germanium is over 4.0 from 1.6 to 20 ?m. The prototype immersion gratings for the mid-InfraRed High dispersion Spectrograph (IRHS) are successfully fabricated by a nano-precision machine and grinding cup of cast iron with electrolytic dressing method.

Ebizuka, Noboru; Oka, Kiko; Yamada, Akiko; Ishikawa, Mami; Kashiwagi, Masako; Kodate, Kashiko; Hirahara, Yasuhiro; Sato, Shuji; Kawabata, Koji S.; Wakaki, Moriaki; Morita, Shinya; Simizu, Tomoyuki; Yin, Shaohui; Omori, Hithoshi; Iye, Masanori

2004-06-01

442

Blazed grating couplers in Unibond SO  

Microsoft Academic Search

ABSTRACT Grating couplers can be more efficient than end-fire coupling, in coupling light into a thin film waveguide (thickness of — Iim and below). The aim of this work is to fabricate a low cost, highly efficient silicon waveguide grating coupler which is to be used at the telecommunication wavelength of 1.3 tim. Silicon-on-insulator (SOl) is chosen for fabricating the

T. W. Mg; A. Vonsovici; A. G. R. Evans; P. R. Routley; M. R. Josey

443

Multiplexed long period gratings with differential interrogation  

NASA Astrophysics Data System (ADS)

In this work we present experimental results in which we simultaneously detect spectral changes of three long period fiber gratings (LPG) connected in series. The gratings can independently measure surrounding refractive index (SRI) changes ?n, temperature T and strain ? in any combination. We have successfully tested them with to simultaneous moisture/evaporation sensing based on SRI change measurements. Such arrangements can be used for simultaneous tracking of hazardous liquid ingress or spill in structural health monitoring applications.

Eftimov, T.; Bock, W.; Mikulic, P.; Nikolova, K.

2010-11-01

444

Background and Scattered-Light Subtraction in the High-Resolution Echelle Modes of the Space Telescope Imaging Spectrograph  

NASA Astrophysics Data System (ADS)

We present a simple, effective approach for estimating the on-order backgrounds of spectra taken with the highest resolution modes of the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. Our scheme for determining the on-order background spectrum for STIS E140H and E230H observations uses moderate-order polynomial fits to the interorder scattered light visible in the two-dimensional STIS MAMA images. We present a suite of high-resolution STIS spectra to demonstrate that our background-subtraction routine produces the correct overall zero point as judged by the small residual flux levels in the centers of strongly saturated interstellar absorption lines. Although there are multiple sources of background light in STIS echelle mode data, this simple approach works very well for wavelengths longward of Ly? (?>~1215 Å). At shorter wavelengths, the smaller order separation and generally lower signal-to-noise ratios of the data can reduce the effectiveness of our background estimation procedure. Slight artifacts in the background-subtracted spectrum can be seen in some cases, particularly at wavelengths of <~1300 Å. Most of these are caused by echelle scattering of strong spectral features into the interorder light. We discuss the limitations of high-resolution STIS data in light of the uncertainties associated with our background-subtraction procedure. We compare our background-subtracted STIS spectra with the Goddard High Resolution Spectrograph (GHRS) Ech-A observations of the DA white dwarf G191-B2B and the GHRS first-order G160M observations of the early-type star HD 218915. We find no significant differences between the GHRS data and the STIS data reduced with our method in either case. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Howk, J. Christopher; Sembach, Kenneth R.

2000-05-01

445

The GRANIT spectrometer  

SciTech Connect

The existence of quantum states of matter in a gravitational field was demonstrated recently in the Institut Laue-Langevin (ILL), Grenoble, in a series of experiments with ultra cold neutrons (UCN). UCN in low quantum states is an excellent probe for fundamental physics, in particular for constraining extra short-range forces; as well as a tool in quantum optics and surface physics. The GRANIT is a follow-up project based on a second-generation spectrometer with ultra-high energy resolution, permanently installed in ILL. It has been constructed in framework of an ANR grant; and will become operational in 2011.

Baessler, Stefan [ORNL; Beau, M [ Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France; Kreuz, Michael [ Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France; Nesvizhevsky, V. [ Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France; Kurlov, V [Institute of Solid State Physics, Russian Ac. Sci., Chernogolovka, Moscow, Russi; Pignol, G [LPSC IN2P3 UJF INPG, R-38026 Grenoble, France; Protasov, K. [LPSC IN2P3 UJF INPG, R-38026 Grenoble, France; Vezzu, Francis [LPSC IN2P3 UJF INPG, R-38026 Grenoble, France; Voronin, Vladimir [Institute of Metal Physics, Russia

2011-01-01

446

Neutron range spectrometer  

DOEpatents

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

Manglos, S.H.

1988-03-10

447

Interface for Mossbauer spectrometer  

SciTech Connect

An interface is described that allows the Elektronika-60M microcomputer to acquire Mossbauer-spectrometer data. The interface uses asynchronous programmable exchange and has four registers with programmable access. Data are accumulated in 1024, 512, 256 and 128 channels. Spectra can be displayed on a video monitor with a variable ordinate-axis scale. An exchange cycle takes 35 microsec. Practical use of the interface has shown that it is reliable, simple to adjust, and convenient to use. Such devices can be useful in data-acquisition systems with low exchange speeds and those that require visual monitoring of data.

Eudokimov, V.A.; Fedorov, A.A.; Kononov, Y.G.; Lobko, A.S.

1985-07-01

448

A far infrared spectrometer.  

PubMed

A moderate resolution vacuum far in spectrometer has been built with a data acquisition system designed for computer processing of the data. The spectral range of the instrument is 20-1600 micro. Sensitive low temperature bolometer detectors have been made of doubly doped silicon. The radiation filtering scheme is discussed in detail. In addition, an analysis is made of the effect of detector noise and impurity radiation on the accuracy of the results. Sample spectra illustrating the performance of the instrument are presented. PMID:20076250

Silvera, I F; Birnbaum, G

1970-03-01

449

Photoacoustic spectrometer for ozone detection  

Microsoft Academic Search

A high-resolution external laser photoacoustic spectrometer has been developed. The spectrometer was used to analyze the absorption transitions of the ozone in coincidence with the CO2 laser emission and to evaluate its limit of sensitivity. A CO2 laser and a photoacoustic resonant cell, totally built in project, formed the spectrometer. The CO2 laser operates in 80 CW transitions distributed in

Edjar M. Telles; Edson Bezerra; Artemio Scalabrin

2001-01-01

450

An antimatter spectrometer in space  

Microsoft Academic Search

We discuss a simple magnetic spectrometer to be installed on a satellite or space station. The purpose of this spectrometer is to search for primordial antimatter to the level of antimatter\\/matter ~10-9,