The US National Science Foundation 4m Daniel K. Inouye Solar Telescope (DKIST) on Haleakala, Maui is the largest solar telescope in the world. DKIST’s superb resolution and polarimetric sensitivity will enable astronomers to explore the origins of solar magnetism, the mechanisms of coronal heating and drivers of flares and coronal mass ejections. DKIST operates as a coronagraph at infrared wavelengths, providing crucial measurements of the magnetic field in the corona. During its Operations Commissioning Phase, DKIST has already conducted a significant number of shared-risk observations for community researchers. The complex raw data are calibrated by the DKIST Data Center located in Boulder and distributed to the science community. We’ll present examples of science results and discuss lessons learned. Ongoing instrument development efforts include, an upgrade of the single-conjugate adaptive optics system to a multi-conjugate AO, the implementation of image slicers for the DL-NIRSP instrument and development of infrared detectors the DL- and CRYO-NIRSP instruments.
Spectro-polarimeters in solar astronomy usually require splitting different wavebands into separate monochromatic arms that operate as independent sub-instruments. We demonstrate a concept for a polarimeter that operates at two wavebands simultaneously, using a single channel of optical components and a single detector. By using chromatic zero-order waveplates, polarized light propagates differently through the instrument depending on its wavelength, allowing to measure the polarization in both wavebands simultaneously. We present Stokes vectors measurements with ∼ 1% relative error using standard off-the-shelf components, thus demonstrating the relevance of this concept for fields like solar astronomy and space instrumentation.
The Daniel K. Inouye Solar Telescope, with its 4m aperture, is the largest telescope for observations of the Sun, and is currently in its Operations Commissioning Phase. During this phase of the project, the five DKIST first light instruments, the Visible Broadband Imager (VBI), the Visible Spectro-Polarimeter (ViSP), the Diffraction-Limited Near-Infrared Spectro-Polarimeter (DL-NIRSP), the Cryogenic Near-Infrared Spectro-Polarimeter (Cryo-NIRSP) and the Visible Tunable Filter (VTF) are used in selected modes to acquire scientific data. We provide an overview of the DKIST instrumentation system and its inherent flexibility. We further report on lessons learned during commissioning, and present sample data products.
The Diffraction-Limited Near Infrared Spectropolarimeter (DL-NIRSP) is a facility instrument of the U.S. National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST). DL-NIRSP was originally commissioned with a birefringent fiber optic image slicer for high resolution observations of the solar atmosphere to support contiguous 2D-spatial, spectral, and polarimetric measurements in three channels between 500 and 1800 nm with very high spectral resolution over narrow bandpasses. During commissioning, we found temporal variations of the flat field and other fiber-related issues limited instrument performance. To resolve these various problems, we replaced the existing fiber-based image slicer with the high resolution Machined Image Slicer Integral Field Unit with 36 micrometer wide slicer mirrors (MISI-36). We report on the implementation and optical testing of MISI-36.
This paper describes Flare Sentinel, a compact integral field spectrograph (IFS) for the study of the hydrogen Balmer series spectrum from 350 to 450 nm of solar flare from space. Flare Sentinel IFS is based on a new Machined Image Slicer Compact Spectrograph Array (MICS) design. MICS consists of an image slicer that divides a continuous 2D spatial field formed by an imaging system into multiple narrow slices, and an array of miniature spectrographs, each forming the spectra of one of the slices of the 2D field. The spectra formed by all the miniature spectrographs can be projected on a common 2D focal plane to be recorded by an image sensors. The spectra can also be distributed to multiple focal planes and recorded simultaneously by multiple sensors to increase the instantaneous hyperspectral field of view of the instrument. New image slicers with slit width of 36 um and 20 um have been successfully fabricated using Canon Inc.’s ultra-precision diamond-cutting CNC mill. This capability is enabling design and fabrication of IFSs with imaging format of 102 × 102 , and spectral resolution between 100 < R < 10, 000 in a very compact package. We will present the optical design and the optical hardware of a prototype IFS that has been fabricated.
Canon has the world's most advanced cutting machine and has provided the world's first CdZnTe1 and InP2 immersion gratings to the market. Cutting gratings on brittle materials is very delicate, and nm-accurate processing can be achieved by cutting alone. Using this technology, we have fabricated the machined image slicer integral field unit (MISI) for the Diffraction-Limited near-IR Spectropolarimeter (DL-NIRSP) 3 of the Daniel K. Inouye Solar Telescope (DKIST) 4 . The MISI-36 we produced is consists of 112 36μm×1.3mm micro slicer mirrors, a parabolic collimator, a monolithic flat mirror array consists of 112-fold mirrors, and a monolithic spherical mirror array consists of 112 spherical mirrors. This paper presents the latest high precision machined and fabricated ultra-compact IFU/ MISI-36.
With the advancements of ultra-high-precision micro-optics fabrication technologies, it is now possible to fabricate integral field units (IFUs) with slicer mirror width of 30 m or less. This paper describes a 36-um machined image slicer IFU (MISI-36) for the Diffraction-Limited near-IR Spectropolarimeter (DL-NIRSP) of the Daniel K. Inouye Solar Telescope (DKIST). MISI-36 has a unique 2-section image slicer design, and is consists of a monolithic image slicer block with 112 micro slicer mirrors, a parabolic collimator, a monolithic flat mirror array consists of 112 fold mirrors, and a monolithic spherical mirror array consists of 112 spherical mirrors. We have successfully fabricated a prototype device using Canon Inc.’s diamond-cutting CNC, and conducted a preliminary performance evaluation using an experimental bench-top spectrograph similar to the spectrograph of DL-NIRSP. We will present the optical design and optical performances of the MISI-36 prototype.
The National Science Foundation’s 4m Daniel K. Inouye Solar Telescope (DKIST) on Haleakala, Maui is now the largest solar telescope in the world. DKIST’s superb resolution and polarimetric sensitivity will enable astronomers to unravel many of the mysteries the Sun presents, including the origin of solar magnetism, the mechanisms of coronal heating and drivers of flares and coronal mass ejections. Five instruments, four of which provide highly sensitive measurements of solar magnetic fields, including the illusive magnetic field of the faint solar corona. DKIST operates as a coronagraph at infrared wavelengths where the sky background is low and bright coronal emission lines are available. The high-order, single-conjugate adaptive optics system (AO) provides diffraction limited imaging and the ability to resolve features approximately 20 km on the Sun. A multi-conjugate AO upgrade is in progress. With these unique capabilities DKIST will address basic research aspects of Space Weather and help improve predictive capabilities. DKIST has completed construction and is now in the early phases of operations. Community proposal-based shared-risk observations are conducted by the DKIST operations team.
With the recent advancement of ultra-high-precision micro-optics fabrication technologies, it is now possible to fabricate IFUs based on machined image slicers with slicer width of 30 um or less. We have developed a machined image slicer IFU (MISI) to replace the BiFOIS IFU of the DL-NIRSP Instrument, one of the first light instrument for the DKIST Telescope. Overall, the IFU contains a total of 336 micro mirrors and a common collimator. The large number of micro optical elements of MISI present a great challenge to the optical and mechanical design process of the IFU. Typical design method that model and position each optical element manually would result in a tedious and lengthy mechanical design process.
This paper describes the CAD design process of MISI using Solidworks macros that were developed to automatically generate all the optical surfaces based on the ZEMAX model data output and also simulating the tool shape and path to generate a precise model of the IFU.
Construction of the Daniel K. Inouye Solar Telescope (DKIST) is well underway on the Haleakalā summit on the Hawaiian island of Maui. Featuring a 4-m aperture and an off-axis Gregorian configuration, the DKIST will be the world’s largest solar telescope. It is designed to make high-precision measurements of fundamental astrophysical processes and produce large amounts of spectropolarimetric and imaging data. These data will support research on solar magnetism and its influence on solar wind, flares, coronal mass ejections, and solar irradiance variability. Because of its large aperture, the DKIST will be able to sense the corona’s magnetic field—a goal that has previously eluded scientists—enabling observations that will provide answers about the heating of stellar coronae and the origins of space weather and exo-weather. The telescope will cover a broad wavelength range (0.35 to 28 microns) and operate as a coronagraph at infrared (IR) wavelengths. Achieving the diffraction limit of the 4-m aperture, even at visible wavelengths, is paramount to these science goals. The DKIST’s state-of-the-art adaptive optics systems will provide diffraction-limited imaging, resolving features that are approximately 20 km in size on the Sun.
At the start of operations, five instruments will be deployed: a visible broadband imager (VTF), a visible spectropolarimeter (ViSP), a visible tunable filter (VTF), a diffraction-limited near-IR spectropolarimeter (DLNIRSP), and a cryogenic near-IR spectropolarimeter (cryo-NIRSP). At the end of 2017, the project finished its fifth year of construction and eighth year overall. Major milestones included delivery of the commissioning blank, the completed primary mirror (M1), and its cell. Commissioning and testing of the coudé rotator is complete and the installation of the coudé cleanroom is underway; likewise, commissioning of the telescope mount assembly (TMA) has also begun. Various other systems and equipment are also being installed and tested. Finally, the observatory integration, testing, and commissioning (IT&C) activities have begun, including the first coating of the M1 commissioning blank and its integration within its cell assembly. Science mirror coating and initial on-sky activities are both anticipated in 2018.
We provide an update on the construction status of the Daniel K. Inouye Solar Telescope. This 4-m diameter facility is designed to enable detection and spatial/temporal resolution of the predicted, fundamental astrophysical processes driving solar magnetism at their intrinsic scales throughout the solar atmosphere. These data will drive key research on solar magnetism and its influence on solar winds, flares, coronal mass ejections and solar irradiance variability. The facility is developed to support a broad wavelength range (0.35 to 28 microns) and will employ state-of-the-art adaptive optics systems to provide diffraction limited imaging, resolving features approximately 20 km on the Sun. At the start of operations, there will be five instruments initially deployed: Visible Broadband Imager (VBI; National Solar Observatory), Visible SpectroPolarimeter (ViSP; NCAR High Altitude Observatory), Visible Tunable Filter (VTF (a Fabry-Perot tunable spectropolarimeter); Kiepenheuer Institute for Solarphysics), Diffraction Limited NIR Spectropolarimeter (DL-NIRSP; University of Hawaii, Institute for Astronomy) and the Cryogenic NIR Spectropolarimeter (Cryo-NIRSP; University of Hawaii, Institute for Astronomy).
As of mid-2016, the project construction is in its 4th year of site construction and 7th year overall. Major milestones in the off-site development include the conclusion of the polishing of the M1 mirror by University of Arizona, College of Optical Sciences, the delivery of the Top End Optical Assembly (L3), the acceptance of the Deformable Mirror System (Xinetics); all optical systems have been contracted and are either accepted or in fabrication. The Enclosure and Telescope Mount Assembly passed through their factory acceptance in 2014 and 2015, respectively. The enclosure site construction is currently concluding while the Telescope Mount Assembly site erection is underway. The facility buildings (Utility and Support and Operations) have been completed with ongoing work on the thermal systems to support the challenging imaging requirements needed for the solar research.
Finally, we present the construction phase performance (schedule, budget) with projections for the start of early operations.
The birefringent fiber optic image slicer design, or BiFOIS, adapts integral field spectroscopy methods to the special needs of high-sensitivity, spatially-resolved spectropolarimetry. In solar astronomy these methods are of particular importance, as dynamic magnetism lies at the heart of various multi-scaled phenomena in the solar atmosphere. While integral field units (IFU) based on fiber optics have been in continual development for some time, standard stock multimode fibers do not typically preserve polarization. The importance of a birefringent fiber optic IFU design stems from the need for dual-beam spatio-temporal polarimetric modulation to correct for spurious polarization signals induced either by platform jitter or atmospheric seeing. Here we characterize the polarization response of a second generation BiFOIS IFU designed for solar spectropolarimetry. The unit provides 60 × 64 spatial imaging pixels in a densely-packed, high filling factor configuration. Particular attention is placed on the spatial uniformity of the IFU polarization response. Calibrated first-light solar observations are also presented to demonstrate the performance of the device in a real application.
The Daniel K. Inouye Solar Telescope (DKIST, renamed in December 2013 from the Advanced Technology Solar
Telescope) will be the largest solar facility built when it begins operations in 2019. Designed and developed to meet the
needs of critical high resolution and high sensitivity spectral and polarimetric observations of the Sun, the observatory
will enable key research for the study of solar magnetism and its influence on the solar wind, flares, coronal mass
ejections and solar irradiance variations. The 4-meter class facility will operate over a broad wavelength range (0.38 to
28 microns, initially 0.38 to 5 microns), using a state-of-the-art adaptive optics system to provide diffraction-limited
imaging and the ability to resolve features approximately 25 km on the Sun. Five first-light instruments will be available
at the start of operations: Visible Broadband Imager (VBI; National Solar Observatory), Visible SpectroPolarimeter
(ViSP; NCAR High Altitude Observatory), Visible Tunable Filter (VTF; Kiepenheuer Institut für Sonnenphysik),
Diffraction Limited Near InfraRed SpectroPolarimeter (DL-NIRSP; University of Hawai’i, Institute for Astronomy) and
the Cryogenic Near InfraRed SpectroPolarimeter (Cryo-NIRSP; University of Hawai’i, Institute for Astronomy).
As of mid-2014, the key subsystems have been designed and fabrication is well underway, including the site
construction, which began in December 2012. We provide an update on the development of the facilities both on site at
the Haleakalā Observatories on Maui and the development of components around the world. We present the overall
construction and integration schedule leading to the handover to operations in mid 2019. In addition, we outline the
evolving challenges being met by the project, spanning the full spectrum of issues covering technical, fiscal, and
geographical, that are specific to this project, though with clear counterparts to other large astronomical construction
projects.
The Massively Multiplexed Spectrograph (mxSPEC) is a new instrument concept that takes advantage of modern high-speed large-format focal plane arrays (FPAs) and high efficiency bandpass isolation filters to multiplex spectra from many slices of the telescope field simultaneously onto the FPAs within a single grating spectrograph. This design greatly reduces the time required to scan a large telescope field, and with current technologies can achieve more than a factor of 50 or more improvement of the system efficiency over a conventional long-slit spectrograph. Furthermore, several spectral lines can be observed at the same time with proper selection of the diffraction grating, further improving the efficiency of this design to more than two orders of magnitude over conventional single-slit, single-wavelength instrument. This paper describes an experimental, proof-of-concept, 40-slit full-disk spectrograph that demonstrates the feasibility of this new instrument concept and its potential for solar physics research including helioseismology, dynamic solar events, and global scale magnetic field observation of the solar disk and the corona. We also present the preliminary design of a 4-line, 55-slit spectroheliograph that can serve as the template for the instruments of the next generation synoptic solar observatory.
KEYWORDS: Visible radiation, Calibration, Solar telescopes, Solar processes, Spatial resolution, Coronagraphy, Near infrared, Data centers, Telescopes, Adaptive optics
The Daniel K. Inouye Solar Telescope is a 4-meter-class all-reflecting telescope under construction on Haleakalā
mountain on the island of Maui, Hawai’i. When fully operational in 2019 it will be the world's largest solar telescope
with wavelength coverage of 380 nm to 28 microns and advanced Adaptive Optics enabling the highest spatial resolution
measurements of the solar atmosphere yet achieved. We review the first-generation DKIST instrument designs, select
critical science program topics, and the operations and data handling and processing strategies to accomplish them.
The SpectroPolarimetric Imager for the Energetic Sun (SPIES) is a project to develop a new class of spectropolarimetric
instrument for the study of highly dynamic solar phenomena. Understanding the physics of dynamic
solar phenomena requires detailed information about the magnetic, thermal, and dynamic properties of the solar
atmosphere at every stage of their evolution. Although these properties can be obtained with existing highperformance
spectropolarimeters such as the SpectroPolarimeter onboard the Hinode space solar observatory or
the Facility IR Spectropolarimeter of the Dunn Solar Telescope, these instruments cannot observe the required
field of view with temporal resolution that can resolve the dynamic timescale of these energetic events. SPIES-2K
is an experimental true-imaging spectropolarimeter developed under this program to address this deficiency in
our observing capability. It is based on a fiber-optic integral field unit containing 2,048 standard multimode
fused silica fibers, and is capable of observing a 64 x 32 pixels field simultaneously with high spatial and spectral
resolution. Moreover, it can obtain the full Stokes spectra of the field with a maximum temporal resolution
of a few seconds. This paper presents the design and characteristics of the instrument, as well as preliminary
results obtained at Fe I 1565 nm wavelength. Additionally, this paper also reports on recent studies of the
polarization maintenance optical fiber ribbon constructed from rectangular element fibers for the Birefringence
Fiber-Optic Image Slicer, and discusses its application to future generation of SPIES and other astronomical
spectropolarimetry projects.
Spectro-polarimetry plays an important role in the study of solar magnetism and strongly influences the design of the
new generation of solar telescopes. Calibration of the polarization properties of the telescope is a critical requirement
needed to use these observations to infer solar magnetic fields. However, the large apertures of these new telescopes
make direct calibration with polarization calibration optics placed before all the telescope optical elements impractical.
It is therefore desirable to be able to infer the polarization properties of the telescope optical elements utilizing solar
observations themselves. Taking advantage of the fact that the un-polarized, linearly, and circularly polarized spectra
originating from the Sun are uncorrelated, we have developed techniques to utilize observations of solar spectra with
redundant combination of the polarization states measured at several different telescope configurations to infer the
polarization properties of the telescope as a whole and of its optical elements. We show results of these techniques
applied to spectro-plarimetric data obtained at the Dunn Solar Telescope.
High-resolution imaging spectropolarimetry in the visible and infrared wavelengths is the most effective and accurate observational diagnostic tool for many astrophysical problems, but many among them also require a spatially resolved two-dimensional field of view. However, it is difficult to achieve simultaneous three-dimensional (x, y, and λ) coverage using instruments with a conventional design. A conventional spectrograph achieves three-dimensional coverage either by scanning a tunable filter through the spectral window of interest, or by scanning a diffraction-grating-based long-slit spectrograph through the target region. Scanning in either spectral or spatial direction unavoidably degrades the quality of the data, and is time consuming. This paper describes a new visible/IR imaging spectropolarimeter design based on a novel birefringent fiber-optic image slicer and multiple-slit spectrograph. With this design, simultaneous 3-D imaging spectropolarimetry of astronomical objects with a large field of view and high spatial and spectral resolution can be achieved.
The Advanced Solar Technology Telescope (ATST) is a 4-m solar telescope being designed for high spatial, spectral and temporal resolution, as well as IR and low-scattered light observations. The overall limit of performance of the telescope is strongly influenced by the qualities of the site at which it is located. Six sites were tested with a seeing monitor and a sky brightness instrument for 1.5 to 2 years. The sites were Big Bear (California), Haleakala (Hawaii), La Palma (Canary Islands, Spain), Panguitch Lake (Utah), Sacramento Peak (New Mexico), and San Pedro Martir (Baja California, Mexico). In this paper we will describe the methods and results of the site survey, which chose Haleakala as the location of the ATST.
The 4-m aperture Advanced Technology Solar Telescope (ATST) is the next generation ground based solar telescope. In this paper we provide an overview of the ATST post-focus instrumentation. The majority of ATST instrumentation is located in an instrument Coude lab facility, where a rotating platform provides image de-rotation. A high order adaptive optics system delivers a corrected beam to the Coude lab facility. Alternatively, instruments can be mounted at Nasmyth or a small Gregorian area. For example, instruments for observing the faint corona preferably will be mounted at Nasmyth focus where maximum throughput is achieved. In addition, the Nasmyth focus has minimum telescope polarization and minimum stray light. We describe the set of first generation instruments, which include a Visible-Light Broadband Imager (VLBI), Visible and Near-Infrared (NIR) Spectropolarimeters, Visible and NIR Tunable Filters, a Thermal-Infrared Polarimeter & Spectrometer and a UV-Polarimeter. We also discuss unique and efficient approaches to the ATST instrumentation, which builds on the use of common components such as detector systems, polarimetry packages and various opto-mechanical components.
The location of the Advanced Technology Solar Telescope (ATST) is a critical factor in the overall performance of the telescope. We have developed a set of instrumentation to measure daytime seeing, sky brightness, cloud cover, water vapor, dust levels, and weather. The instruments have been located at six sites for periods of one to two years. Here we describe the sites and instrumentation, discuss the data reduction, and present some preliminary results. We demonstrate that it is possible to estimate seeing as a function of height near the ground with an array of scintillometers, and that there is a distinct qualitative difference in daytime seeing between sites with or without a nearby lake.
KEYWORDS: Telescopes, Mirrors, Solar radiation, Solar energy, Coronagraphy, Solar telescopes, Reflectivity, Optical design, Solar processes, Ray tracing
A new generation of off-axis telescopes has been proposed to address a number of high dynamic range problems in astrophysics. These systems present unusual problems and opportunities for the instrument designer. We will discuss some of the issues that must be resolved when placing instrumentation at the prime focus. The heat stop and occulter systems for the SOLARC off-axis coronagraph will be used to illustrate strategies for solar telescope applications.
The development of new solar IR instrumentation in the past decade had opened new windows of opportunity for solar physics research which were not accessible before. Many spectral lines in the near-IR wavelength range from 1 to 2 microns offer powerful diagnostics for the study of solar magnetism in the photosphere, the chromosphere, and the corona. Significant progress and breakthroughs were made in areas such as the generation of weak background magnetic fields by small-scale surface dynamos, the physics of the sunspot, and the direct measurement of magnetic fields in the corona. The combination of these new IR diagnostics tools, and the unprecedented 4-meter aperture and versatile photospheric and coronal capabilities of the Advanced Technology Solar Telescope (ATST), will greatly enhance our capability to study the Sun. It further promises breakthrough observations that can help to resolve many of the long-standing mysteries of solar physics. The instruments for the ATST will need to accommodate a broad range of science subjects, each with its unique observational requirements. This paper examine the near-IR instrumentation required to achieve the ATST science goals, and present conceptual designs of a near-IR SpectroPolarimeter (NIRSP) aimed at addressing the new challenges of observational solar physics brought upon by the ATST.
A 0.5m aperture off-axis coronagraphic telescope is described. Its fabrication, imaging, and scattered light performance is discussed in the context of simple model expectations.
NICO, the Near Infrared Chromosphere Observatory, is a platform for determining the magnetic structure and fources of heating for the solar chromosphere. NICO, a balloon-borne observatory, will use the largest solar telescope flying to map the magnetic fields, velocities, and heating events of the chromosphere and photosphere in detail. NICO will introduce new technologies to solar flight missions, such as wavefront sensing for monitoring telescope alignment, real-time correlation tracking and high-speed image motion compensation, and wide aperture Fabry-Perot etalons for extended spectral scanning.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.