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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Multiple object fiber optics spectrograph feed for the Hale telescope

The preliminary design for a computer-controlled fiber-optics feed linking the 5-m Hale telescope at Palomar Observatory to the entrance slit of an astronomical spectrograph is presented. A 76-mm square field will be divided into ten strips containing two movable fibers each; the fibers can be moved by stepper-motor-driven lead screws to any position on the strip. The device is designed to allow the simultaneous spectrographic observation of many astronomical objects in a small angular field. A prototype feed using two fibers and manually commanded digital control is described in detail. Test observations of two bright O stars made in April, 1981 using the prototype with the Hale telescope are considered sufficiently positive to warrant construction of the 20-fiber feed, which would enhance the spectrographic-survey effectiveness of the telescope by a factor of ten.

Tubbs, E. F.↗
NASA NTRS1983

Interfacing a Two-Stage Image Intensifier Tube to an Echelle Spectrograph

An Echelle spectrograph has been in use at the Marshall Space Flight Center for a number of years. Research has been carried out in the study of the internal motions of ionized gas clouds in the interstellar medium. In order to extend the ability of the spectrograph to allow investigations of the faint outer regions of the gas clouds and to make possible the initiatiion of new research programs dealing with the study of sunspots and the zodiacal light, a two-stage image intensifier tube was incorporated into the instrument. The objective of this work was to interface the image tube with the spectrograph.

Flesch, T. R.↗
NASA NTRS1987

Designing Echelle Spectrographs

Performance numbers and output maps computed from inputs supplied by user. Echelle Spectrograph Design Aid program (EGRAM) aids in design of spectrographic systems that utilize echelle/first-order crossdisperser combinations. Optical combination causes two-dimensional echellogram to fall on detector. Describes echellogram with enough detail to enable user to judge effectively feasibility of spectrograph design. By iteratively altering system parameters, desired echellogram achieved without making physical model. Calculates system parameters accurately to first order and compare favorably to results from raytracing techniques. EGRAM written in two versions. FORTRAN 77, and Microsoft BASIC A.

Dantzler, A.↗
NASA NTRS1986

The Space Telescope imaging spectrograph

Preliminary performance goals for the Space Telescope Imaging Spectrograph (STIS), selected by NASA for definition study as a second generation instrument on the Hubble Space Telescope (HST) are outlined. The STIS is a 2-dimensional spectrograph that will operate from 1050A-11000A at the limiting HST spatial resolution of 0.05 arcsec FWHM, with spectral resolutions of 100, 1200, 20,000, and 100,000 and a maximum field-of-view of 50X50 arcsec. Its basic operating modes include echelle mode (like IUE), long slit mode (for simultaneous spectra at 1000 positions on the target), slitless spectrograph mode, coronographic spectroscopy, photon time-tagging, and direct imaging.

Gull, Theodore R.↗
NASA NTRS1991

Aberration corrected aspheric grating for far ultraviolet spectrographs - Conventional approach

Two approaches to reducing optical aberrations of concave grating spectrographs have been used, holographically controlling the groove curvature and spacing and reshaping the optical substrate while ruling the grooves conventionally. The latter approach, slightly deforming an ellipsoidal grating blank, can lead to diffraction-limited performance at a single FUV wavelength. When such a grating is used in a slitted Rowland circle spectrograph, the result is an extremely efficient spectrograph with spectral resolving power of about 30,000 and low astigmatism. Optical fabrication technology has advanced to the point where these exotic surface gratings are becoming practical.

Content, David↗
NASA NTRS1992

An EUV imaging spectrograph for high-resolution observations of the solar corona

An extreme ultraviolet (EUV) imaging spectrograph for the wavelength range from 235 to 450 A has been developed and used for resolution observations of the sun. The instrument incorporates a glancing incidence Wolter Type II Telescope and a near-normal incidence toroidal grating spectrograph to achieve near-stigmatic performance over this spectral range. The design of the spectrograph entrance aperture enables both stigmatic spectra with spectral resolution adequate to observe emission line profiles and spectroheliograms of restricted portions of the sun to be obtained concurrently. The design and performance of the instrument are described, and an overview of results obtained during a sounding rocket flight on May 5, 1989 is provided.

Neupert, Werner M.↗
NASA NTRS1995

PRISM Spectrograph Optical Design

The objective of this contract is to explore optical design concepts for the PRISM spectrograph and produce a preliminary optical design. An exciting optical configuration has been developed which will allow both wavelength bands to be imaged onto the same detector array. At present the optical design is only partially complete because PRISM will require a fairly elaborate optical system to meet its specification for throughput (area*solid angle). The most complex part of the design, the spectrograph camera, is complete, providing proof of principle that a feasible design is attainable. This camera requires 3 aspheric mirrors to fit inside the 20x60 cm cross-section package. A complete design with reduced throughput (1/9th) has been prepared. The design documents the optical configuration concept. A suitable dispersing prism material, CdTe, has been identified for the prism spectrograph, after a comparison of many materials.

Chipman, Russell A.↗
NASA NTRS1997

Development of the MAMA Detectors for the Hubble Space Telescope Imaging Spectrograph

The development of the Multi-Anode Microchannel Array (MAMA) detector systems started in the early 1970's in order to produce multi-element detector arrays for use in spectrographs for solar studies from the Skylab-B mission. Development of the MAMA detectors for spectrographs on the Hubble Space Telescope (HST) began in the late 1970's, and reached its culmination with the successful installation of the Space Telescope Imaging Spectrograph (STIS) on the second HST servicing mission (STS-82 launched 11 February 1997). Under NASA Contract NAS5-29389 from December 1986 through June 1994 we supported the development of the MAMA detectors for STIS, including complementary sounding rocket and ground-based research programs. This final report describes the results of the MAMA detector development program for STIS.

Timothy, J. Gethyn↗
NASA NTRS1998

A Very High Resolution Mid Infrared Spectrograph for SOFIA

The purpose of this project was to study the design of a high resolution mid-infrared spectrograph for the SOFIA airborne observatory. The primary motivation for the construction and use of such an instrument is the study of vibrational transitions of molecules in molecular clouds, circumstellar inflows and outflows, and planetary atmospheres, which are blocked from ground-based observations by absorption by the Earth's atmosphere. The instrument design studied is a cross-dispersed grating spectrograph with several modes of operation giving spectral resolving powers of approximately 4000, 20,000, and 100,000. In the two lower resolution modes a single grating is used in a long-slit spectrograph. At high resolution that grating serves as the cross-disperser for a 1-m long echelon, a very coarsely and steeply ruled grating, diamond-machined in aluminum. Several design study tasks were carried out: 1. An optical and mechanical design was developed. It differed from the preliminary design by using a reflecting focal reducer in the fore-optics and by rearranging the echelon and cross-dispersing chambers to improve the efficiency of the long-slit modes. 2. A finite-element analysis of the dewar and echelon support structures was done. It led us to change the echelon support to improve its rigidity. 3. Further information was obtained which convinced us that Hyperfine Inc. was capable of diamond-machining the echelon. 4. Several possible vendors of readout electronics and software were identified. It was decided that it is more cost-effective to purchase these items rather than developing them ourselves. 5. Observing and calibration procedures were studied. we did not identify significant changes needed from procedures used previously. 6. Possible expansions of instrument capabilities, including wavelength coverage, were studied. It appears unlikely that the echelon will perform well at wavelengths shortward of 5 microns, but the spectral coverage could be extended longward of 28 microns with the use of an Si:Sb detector. No patentable inventions were made during this study. Based on this design study, a proposal was submitted to construct the instrument. It was chosen as one of the first-light instruments for SOFIA.

Lacy, John H.↗
NASA NTRS2003

An Ultraviolet Imaging Spectrograph for JIMO

It is vital to include an ultraviolet spectrograph as part of the JIMO payload to Europa, Ganymede and Callisto. Ultraviolet measurements are key for understanding the atmospheres, auroral activity and surfaces of these icy satellites, and a UV imaging spectrograph will also complement a visible camera and near-IR spectrometer, to achieve full wavelength coverage in remote sensing of the icy satellites. The UV instrument proposed for JIMO will be similar to that currently on board the Cassini spacecraft. The design draws on the experience of building UV spectrometers for Mariner, Pioneer, Galileo and Cassini. It will have three spectrographic channels that provide images and spectra of the atmosphere, aurorae and surface: An EUV channel (800-110 nm), an FUV channel (110 to 190 nm) range, and an NUV channel (180 to 350 nm).

Hendrix, A. R.↗
NASA NTRS2018

On the Development of the Marshall Grazing Incidence X-ray Spectrograph (MaGIXS) Mirrors

The Marshall Grazing Incidence X-ray Spectrograph (MaGIXS) is a sounding rocket experiment that will obtain spatially resolved soft X-ray spectra of the solar corona from 0.5 - 2 keV. The optical system comprises a Wolter-I telescope mirror, a slit spectrograph, and a CCD camera. The spectrograph has a finite conjugate paraboloid pair, which re-images the slit, and a varied line-space planar reflection grating. Both the Wolter-I mirror and paraboloid pair are being fabricated at the NASA Marshall Space Flight Center (MSFC), using nickel replication. The MaGIXS mirror mandrels have been diamond turned, polished, and have yielded a set of engineering mirrors. Unlike other grazing incidence instruments, such as FOXSI, ART-XC, and IXPE, the MaGIXS prescriptions have large departure from a cone. This property exacerbates challenges with conventional lap polishing techniques and interferometric metrology. Here we discuss the progression of the optical surfaces of the mandrels through lap polishing, X-ray data from the replicated shells obtained in the MSFC Stray Light Facility (SLF), and our transition to using the ZEEKO computer numerical controlled (CNC) polisher for figure correction.

Champey, Patrick↗
NASA NTRSDate not supplied

Probing the Sun with Imaging Spectrographs

EUV and X-ray images of the Sun have revolutionized our understanding of our closest star. With them, we can probe the morphology and temperature structure of the solar atmosphere and see how they evolve as a function of space and time. However, image data cannot be used to determine line-of-sight velocities, abundances, or densities. This information is required to calculate the energy budget of eruptive events, provide boundary conditions for global solar models, and explore fundamental processes occurring in the solar atmosphere. For those diagnostics, we require spectroscopy. Because the structures on the Sun are extended sources, most modern-day spectrographs observe the Sun through long narrow slits. Two-dimensional, spectrally pure solar images with velocity, abundance, and density information are built up by stepping the slit over regions of interest. This mode of operation implies that two-dimensional information is highly limited by cadence and the temporal evolution and spatial structure of these parameters can never be truly separated. Both spatial and spectral information can be obtained in a single snapshot with slitless spectrographs, which were often used in the 1950-1970s, but were abandoned due to the difficulty of unfolding the overlapping spatial and spectral information. Thanks to advances in computer processing speeds and machine learning algorithms, there have been several techniques developed to complete the spatial/spectral unfolding, unlocking the full capability of slitless spectrographs for solar observations. The goal of this talk is to give a broad overview of the capability of such instruments and demonstrate their usefulness in the next decade of solar observatories and beyond.

Amy Winebarger↗
NASA NTRS2022

Real-Time Exposure Control and Instrument Operation With the NEID Spectrograph GUI

The NEID spectrograph on the WIYN 3.5-m telescope at Kitt Peak has completed its first full year of science operations and is reliably delivering sub-m/s precision radial velocity measurements. The NEID instrument control system uses the TIMS package (Bender et al. 2016), which is a client-server software system built around the twisted python software stack. During science observations, interaction with the NEID spectrograph is handled through a pair of graphical user interfaces (GUIs), written in PyQT, which wrap the underlying instrument control software and provide straightforward and reliable access to the instrument. Here, we detail the design of these interfaces and present an overview of their use for NEID operations. Observers can use the NEID GUIs to set the exposure time, signal-to-noise ratio (SNR) threshold, and other relevant parameters for observations, configure the calibration bench and observing mode, track or edit observation metadata, and monitor the current state of the instrument. These GUIs facilitate automatic spectrograph configuration and target ingestion from the nightly observing queue, which improves operational efficiency and consistency across epochs. By interfacing with the NEID exposure meter, the GUIs also allow observers to monitor the progress of individual exposures and trigger the shutter on user-defined SNR thresholds. In addition, inset plots of the instantaneous and cumulative exposure meter counts as each observation progresses allow for rapid diagnosis of changing observing conditions as well as guiding failure and other emergent issues.

Arvind F Gupta↗
NASA NTRS2015

PISCES High Contrast Integral Field Spectrograph Simulations and Data Reduction Pipeline

The PISCES (Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies) is a lenslet array based integral field spectrograph (IFS) designed to advance the technology readiness of the WFIRST (Wide Field Infrared Survey Telescope)-AFTA (Astrophysics Focused Telescope Assets) high contrast Coronagraph Instrument. We present the end to end optical simulator and plans for the data reduction pipeline (DRP). The optical simulator was created with a combination of the IDL (Interactive Data Language)-based PROPER (optical propagation) library and Zemax (a MatLab script), while the data reduction pipeline is a modified version of the Gemini Planet Imager's (GPI) IDL pipeline. The simulations of the propagation of light through the instrument are based on Fourier transform algorithms. The DRP enables transformation of the PISCES IFS data to calibrated spectral data cubes.

The PISCES (Prototype Imaging Spectrograph for Cor↗
NASA NTRS2016

PISCES: An Integral Field Spectrograph Technology Demonstration for the WFIRST Coronagraph

We present the design, integration, and test of the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) integral field spectrograph (IFS). The PISCES design meets the science requirements for the Wide-Field Infra Red Survey Telescope (WFIRST) Coronagraph Instrument (CGI). PISCES was integrated and tested in the integral field spectroscopy laboratory at NASA Goddard. In June 2016, PISCES was delivered to the Jet Propulsion Laboratory (JPL) where it was integrated with the Shaped Pupil Coronagraph (SPC) High Contrast Imaging Testbed (HCIT). The SPC/PISCES configuration will demonstrate high contrast integral field spectroscopy as part of the WFIRST CGI technology development program.

Prototype Imaging Spectrograph for Coronagraphic E↗
NASA NTRSDate not supplied

A New Integral Field Spectrograph for Broadband Coronagraph Demonstrations at the High Contrast Imaging Testbed Facility

An integral field spectrograph (IFS) camera may help fulfill the exoplanet characterization goals of a future Habitable Worlds Observatory. During the Nancy Grace Roman Space Telescope mission formulation phase, the Coronagraph Instrument Project established the laboratory performance baseline of a combined coronagraph and IFS system with the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES; 1E-8 contrast over an 18% bandpass; 3--9 lambda/D bowtie-shaped control region). New laboratory demonstrations are needed to expand on this milestone in terms of contrast, bandpass, and field of view towards the requirements of a future mission capable of characterizing the atmospheres of Earth-like exoplanets. Here we present the design of a successor to PISCES that can observe a 20 lambda/D-diameter field of view with an instantaneous bandpass up to 30%, at a resolving power R > 70 at visible wavelengths. This instrument will interface with the existing coronagraph layout in the High Contrast Imaging Facility DST-2 vacuum chamber. The addition of a spectroscopic imaging camera at HCIT will benefit the wider coronagraph technology community by enabling other NASA-supported investigators to automatically obtain multi-wavelength measurements of speckles both inside and outside of their control region, and the instrument will support community-led demonstrations of high-order wavefront sensing and control techniques such as dark hole maintenance and linear dark field control.

coronagraph↗