26,116 research outputs found
High-contrast integral field spectrograph (HCIFS): multi-spectral wavefront control and reduced-dimensional system identification
Any high-contrast imaging instrument in a future large space-based telescope will include an integral field spectrograph (IFS) for measuring broadband starlight residuals and characterizing the exoplanetâs atmospheric spectrum. In this paper, we report the development of a high-contrast integral field spectrograph (HCIFS) at Princeton University and demonstrate its application in multi-spectral wavefront control. Moreover, we propose and experimentally validate a new reduced-dimensional system identification algorithm for an IFS imaging system, which improves the systemâs wavefront control speed, contrast and computational and data storage efficiency
High-Contrast Integral Field Spectrograph (HCIFS): multi-spectral wavefront control and reduced-dimensional system identification
Any high-contrast imaging instrument in a future large space-based telescope
will include an integral field spectrograph (IFS) for measuring broadband
starlight residuals and characterizing the exoplanet's atmospheric spectrum. In
this paper, we report the development of a high-contrast integral field
spectrograph (HCIFS) at Princeton University and demonstrate its application in
multi-spectral wavefront control. Moreover, we propose and experimentally
validate a new reduced-dimensional system identification algorithm for an IFS
imaging system, which improves the system's wavefront control speed, contrast
and computational and data storage efficiency.Comment: This paper has been accepted to Optics Expres
Progress towards recalibration of spectrographs
The spectral resolution of a spectrograph depends on the input slit width, the diffraction grating grooves and the number of imaging sensor/detector pixels. Due to the proprietary nature of spectrograph designs, recalibration by end-users can be challenging. Most calibration procedures currently published are applicable to in-house instruments or spectrographs with access to the internal specifications. Narrowing the input slit improves the resolution but also reduces the throughput of the imaging system. We attempted to recalibrate an Offner-based spectrograph by using a larger detector plane (an imaging system with a larger sensor), to vary the distance along the focal plane; and by utilising lens optics. Basic experiments were conducted by varying the distance from the exit window and inserting a lens to magnify the spectrograph output onto the larger detector plane. We concluded that the calibration could not be achieved using simple optics within the scope of our experiments. This article addresses a gap in literature that does not present the research community with the unsuccessful steps that are not applicable to similar problem statements. The alternative would be to rely on reflective optics, but this approach may reduce portability
The Infrared Imaging Spectrograph (IRIS) for TMT: Instrument Overview
We present an overview of the design of IRIS, an infrared (0.84 - 2.4 micron)
integral field spectrograph and imaging camera for the Thirty Meter Telescope
(TMT). With extremely low wavefront error (<30 nm) and on-board wavefront
sensors, IRIS will take advantage of the high angular resolution of the narrow
field infrared adaptive optics system (NFIRAOS) to dissect the sky at the
diffraction limit of the 30-meter aperture. With a primary spectral resolution
of 4000 and spatial sampling starting at 4 milliarcseconds, the instrument will
create an unparalleled ability to explore high redshift galaxies, the Galactic
center, star forming regions and virtually any astrophysical object. This paper
summarizes the entire design and basic capabilities. Among the design
innovations is the combination of lenslet and slicer integral field units, new
4Kx4k detectors, extremely precise atmospheric dispersion correction, infrared
wavefront sensors, and a very large vacuum cryogenic system.Comment: Proceedings of the SPIE, 9147-76 (2014
Airborne Visible/Infrared Imaging spectrometer AVIS: Design, characterization and calibration
The Airborne Visible/Infrared imaging Spectrometer AVIS is a hyperspectral imager designed for environmental monitoring purposes. The sensor, which was constructed entirely from commercially available components, has been successfully deployed during several experiments between 1999 and 2007. We describe the instrument design and present the results of laboratory characterization and calibration of the system's second generation, AVIS-2, which is currently being operated. The processing of the data is described and examples of remote sensing reflectance data are presented
The Interface Region Imaging Spectrograph (IRIS)
The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft
provides simultaneous spectra and images of the photosphere, chromosphere,
transition region, and corona with 0.33-0.4 arcsec spatial resolution, 2 s
temporal resolution and 1 km/s velocity resolution over a field-of-view of up
to 175 arcsec x 175 arcsec. IRIS was launched into a Sun-synchronous orbit on
27 June 2013 using a Pegasus-XL rocket and consists of a 19-cm UV telescope
that feeds a slit-based dual-bandpass imaging spectrograph. IRIS obtains
spectra in passbands from 1332-1358, 1389-1407 and 2783-2834 Angstrom including
bright spectral lines formed in the chromosphere (Mg II h 2803 Angstrom and Mg
II k 2796 Angstrom) and transition region (C II 1334/1335 Angstrom and Si IV
1394/1403 Angstrom). Slit-jaw images in four different passbands (C II 1330, Si
IV 1400, Mg II k 2796 and Mg II wing 2830 Angstrom) can be taken simultaneously
with spectral rasters that sample regions up to 130 arcsec x 175 arcsec at a
variety of spatial samplings (from 0.33 arcsec and up). IRIS is sensitive to
emission from plasma at temperatures between 5000 K and 10 MK and will advance
our understanding of the flow of mass and energy through an interface region,
formed by the chromosphere and transition region, between the photosphere and
corona. This highly structured and dynamic region not only acts as the conduit
of all mass and energy feeding into the corona and solar wind, it also requires
an order of magnitude more energy to heat than the corona and solar wind
combined. The IRIS investigation includes a strong numerical modeling component
based on advanced radiative-MHD codes to facilitate interpretation of
observations of this complex region. Approximately eight Gbytes of data (after
compression) are acquired by IRIS each day and made available for unrestricted
use within a few days of the observation.Comment: 53 pages, 15 figure
LIINUS/SERPIL: a design study for interferometric imaging spectroscopy at the LBT
LIINUS/SERPIL is a design study to augment LBTs interferometric beam combiner
camera LINC-NIRVANA with imaging spectroscopy. The FWHM of the interferometric
main beam at 1.5 micron will be about 10 mas, offering unique imaging and
spectroscopic capabilities well beyond the angular resolution of current 8-10m
telescopes. At 10 mas angular scale, e.g., one resolution element at the
distance of the Galactic Center corresponds to the average diameter of the
Pluto orbit (79 AU), hence the size of the solar system. Taking advantage of
the LBT interferometric beam with an equivalent maximum diameter of 23 m,
LIINUS/SERPIL is an ideal precursor instrument for (imaging) spectrographs at
extremely large full aperture telescopes. LIINUS/SERPIL will be built upon the
LINC-NIRVANA hardware and LIINUS/SERPIL could potentially be developed on a
rather short timescale. The study investigates several concepts for the optical
as well as for the mechanical design. We present the scientific promises of
such an instrument together with the current status of the design study.Comment: 12 pages, SPIE conference proceeding, Orlando, 200
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