66,118 research outputs found
Stable fiber-illumination for extremely precise radial velocities with NEID
NEID is a high-resolution red-optical precision radial velocity (RV)
spectrograph recently commissioned at the WIYN 3.5 m telescope at Kitt Peak
National Observatory, Arizona, USA. NEID has an extremely stable environmental
control system, and spans a wavelength range of 380 to 930 nm with two
observing modes: a High Resolution (HR) mode at R 112,000 for maximum RV
precision, and a High Efficiency (HE) mode at R 72,000 for faint
targets. In this manuscript we present a detailed description of the components
of NEID's optical fiber feed, which include the instrument, exposure meter,
calibration system, and telescope fibers. Many parts of the optical fiber feed
can lead to uncalibratable RV errors, which cannot be corrected for using a
stable wavelength reference source. We show how these errors directly cascade
down to performance requirements on the fiber feed and the scrambling system.
We detail the design, assembly, and testing of each component. Designed and
built from the bottom-up with a single-visit instrument precision requirement
of 27 , close attention was paid to the error contribution
from each NEID subsystem. Finally, we include the lab and on-sky tests
performed during instrument commissioning to test the illumination stability,
and discuss the path to achieving the instrumental stability required to search
for a true Earth twin around a Solar-type star.Comment: Accepted in A
The Maunakea Spectroscopic Explorer Book 2018
(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is
intended as a concise reference guide to all aspects of the scientific and
technical design of MSE, for the international astronomy and engineering
communities, and related agencies. The current version is a status report of
MSE's science goals and their practical implementation, following the System
Conceptual Design Review, held in January 2018. MSE is a planned 10-m class,
wide-field, optical and near-infrared facility, designed to enable
transformative science, while filling a critical missing gap in the emerging
international network of large-scale astronomical facilities. MSE is completely
dedicated to multi-object spectroscopy of samples of between thousands and
millions of astrophysical objects. It will lead the world in this arena, due to
its unique design capabilities: it will boast a large (11.25 m) aperture and
wide (1.52 sq. degree) field of view; it will have the capabilities to observe
at a wide range of spectral resolutions, from R2500 to R40,000, with massive
multiplexing (4332 spectra per exposure, with all spectral resolutions
available at all times), and an on-target observing efficiency of more than
80%. MSE will unveil the composition and dynamics of the faint Universe and is
designed to excel at precision studies of faint astrophysical phenomena. It
will also provide critical follow-up for multi-wavelength imaging surveys, such
as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field
Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation
Very Large Array.Comment: 5 chapters, 160 pages, 107 figure
Maunakea Spectroscopic Explorer (MSE) - The Prime Focus Subsystems: Requirements and Interfaces
MSE will be a massively multiplexed survey telescope, including a segmented
primary mirror which feeds fibers at the prime focus, including an array of
approximately four thousand fibers, positioned precisely to feed banks of
spectrographs several tens of meters away. We describe the process of mapping
top-level requirements on MSE to technical specifications for subsystems
located at the MSE prime focus. This includes the overall top-level
requirements based on knowledge of similar systems at other telescopes and how
those requirements were converted into specifications so that the subsystems
could begin working on their Conceptual Design Phases. We then discuss the
verification of the engineering specifications and the compiling of lower-level
requirements and specifications into higher level performance budgets (e.g.
Image Quality). We also briefly discuss the interface specifications, their
effect on the performance of the system and the plan to manage them going
forward. We also discuss the opto-mechanical design of the telescope top end
assembly and refer readers to more details for instrumentation located at the
top end.Comment: 14 pages; Proceedings of SPIE Astronomical Telescopes +
Instrumentation 2018; Modeling, Systems Engineering, and Project Management
for Astronomy VII
Fiber optic (flight quality) sensors for advanced aircraft propulsion
Development of flight prototype, fiber-optic sensing system components for measuring nine sensed parameters (three temperatures, two speeds, three positions, and one flame) on an F404-400 aircraft engine is described. Details of each sensor's design, functionality, and environmental testing, and the electro-optics architecture for sensor signal conditioning are presented. Eight different optical sensing techniques were utilized. Design, assembly, and environmental testing of an engine-mounted, electro-optics chassis unit (EOU), providing MIL-C-1553 data output, are related. Interconnection cables and connectors between the EOU and the sensors are identified. Results of sensor/cable/circuitry integrated testing, and installation and ground testing of the sensor system on an engine in October 1993 and April 1994 are given, including comparisons with the engine control system's electrical sensors. Lessons learned about the design, fabrication, testing, and integration of the sensor system components are included
Hectospec, the MMT's 300 Optical Fiber-Fed Spectrograph
The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT
in the spring of 2004. A pair of high-speed six-axis robots move the 300 fiber
buttons between observing configurations within ~300 s and to an accuracy ~25
microns. The optical fibers run for 26 m between the MMT's focal surface and
the bench spectrograph operating at R~1000-2000. Another high dispersion bench
spectrograph offering R~5,000, Hectochelle, is also available. The system
throughput, including all losses in the telescope optics, fibers, and
spectrograph peaks at ~10% at the grating blaze in 1" FWHM seeing. Correcting
for aperture losses at the 1.5" diameter fiber entrance aperture, the system
throughput peaks at 17%. Hectospec has proven to be a workhorse
instrument at the MMT. Hectospec and Hectochelle together were scheduled for
1/3 of the available nights since its commissioning. Hectospec has returned
\~60,000 reduced spectra for 16 scientific programs during its first year of
operation.Comment: 68 pages, 28 figures, to appear in December 2005 PAS
The Multi-Object, Fiber-Fed Spectrographs for SDSS and the Baryon Oscillation Spectroscopic Survey
We present the design and performance of the multi-object fiber spectrographs
for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon
Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999
on the 2.5-m aperture Sloan Telescope at Apache Point Observatory, the
spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II
surveys, enabling a wide variety of Galactic and extra-galactic science
including the first observation of baryon acoustic oscillations in 2005. The
spectrographs were upgraded in 2009 and are currently in use for BOSS, the
flagship survey of the third-generation SDSS-III project. BOSS will measure
redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyman-alpha
absorption of 160,000 high redshift quasars over 10,000 square degrees of sky,
making percent level measurements of the absolute cosmic distance scale of the
Universe and placing tight constraints on the equation of state of dark energy.
The twin multi-object fiber spectrographs utilize a simple optical layout
with reflective collimators, gratings, all-refractive cameras, and
state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in
two channels over a bandpass covering the near ultraviolet to the near
infrared, with a resolving power R = \lambda/FWHM ~ 2000. Building on proven
heritage, the spectrographs were upgraded for BOSS with volume-phase
holographic gratings and modern CCD detectors, improving the peak throughput by
nearly a factor of two, extending the bandpass to cover 360 < \lambda < 1000
nm, and increasing the number of fibers from 640 to 1000 per exposure. In this
paper we describe the original SDSS spectrograph design and the upgrades
implemented for BOSS, and document the predicted and measured performances.Comment: 43 pages, 42 figures, revised according to referee report and
accepted by AJ. Provides background for the instrument responsible for SDSS
and BOSS spectra. 4th in a series of survey technical papers released in
Summer 2012, including arXiv:1207.7137 (DR9), arXiv:1207.7326 (Spectral
Classification), and arXiv:1208.0022 (BOSS Overview
EXOhSPEC folded design optimization and performance estimation
The EXOplanet high resolution SPECtrograph (EXOhSPEC) instrument is an echelle spectrograph dedicated to the detection of exoplanets by using the radial velocity method using 2m class telescopes. This spectrograph is specified to provide spectra with a spectral resolution R < 70, 000 over the spectral range from 400 to 700 nm and to reach a shortterm radial velocity precision of 3 m/s. To achieve this the separation between two adjacent spectral orders is specified to be greater than 30 pixels and to enable a wide range of targets the throughput of the instrument is specified to be higher than 4%. We present the results of the optimization of the spectrograph collimator performed and initial tests of its optical performance. First, we consider the spectrograph design and we estimate its theoretical performance. We show that the theoretical image quality is close to the diffraction limit. Second, we describe the method used to perform the tolerancing analyzes using ZEMAX software to estimate the optical performance of the instrument after manufacturing, assembly and alignment. We present the results of the performance budget and we show that the estimated image quality performance of EXOhSPEC are in line with the specifications. Third, we present the results of the stray light analysis and we show that the minimum ratio between the scientific signal and the stray light halo signal is higher than 1,000. Finally, we provide a status on the progress of the EXOhSPEC project and we show the first results obtained with a preliminary version of the prototype.Final Accepted Versio
JOKARUS - Design of a compact optical iodine frequency reference for a sounding rocket mission
We present the design of a compact absolute optical frequency reference for
space applications based on hyperfine transitions in molecular iodine with a
targeted fractional frequency instability of better than . It
is based on a micro-integrated extended cavity diode laser with integrated
optical amplifier, fiber pigtailed second harmonic generation wave-guide
modules, and a quasi-monolithic spectroscopy setup with operating electronics.
The instrument described here is scheduled for launch end of 2017 aboard the
TEXUS 54 sounding rocket as an important qualification step towards space
application of iodine frequency references and related technologies. The
payload will operate autonomously and its optical frequency will be compared to
an optical frequency comb during its space flight
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