The Swift Solar Activity X-ray Imager (SSAXI-Rocket) is a ride-along instrument to the High-Resolution Coronal Imager (Hi-C) Flare NASA sounding rocket launch campaign scheduled for the Spring 2024. In the short 5- minute rocket flight, SSAXI-Rocket will measure the soft X-ray near-peak emission phase of a large solar flare of GOES C-class or greater. The SSAXI-Rocket instrument has peak sensitivity to 10 MK solar plasma, similar to the current Hi-C flare extreme ultraviolet instruments, providing the exploration of the variability in heating and energy transport of solar flares. SSAXI-Rocket combines small X-ray focusing optic (Wolter-I) with onaxis imaging resolution of 9 arcseconds or better and high-speed readout CMOS detector, to image the flare soft X-rays at 5 hertz or faster, with minimized image saturation and pixel signal blooming. These high-time cadence measurements can help uncover the soft X-ray intensity variations which can provide constraints on the intermittent heating processes in the flare magnetic loops. SSAXI-Rocket is the testbed for technology that is planned for future heliophysics and astronomy SmallSat, CubeSat, and large satellite X-ray observatories.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a sounding rocket mission that completed a successful flight from the White Sands Missile Range on July 30, 2021. MaGIXS captured spatially resolved soft X-ray spectra from portions of two solar active regions during its roughly 5-minute flight. The instrument was originally designed as a grazing incidence slit spectrograph but flew in a slit-less configuration that produced overlapping spectroheliograms. For the second flight, MaGIXS-2, the instrument has been reconfigured to a more simplified optical layout that reuses the Wolter-I telescope and blazed varied-line space reflective grating. The field stop at the telescope focal plane and the finite conjugate spectrometer mirror pair have been removed – the telescope now directly feeds the grating. Additionally, an identical but new 2k x 1k CCD camera has been built for this flight. The MaGIXS-2 data product will again be overlapping spectroheliograms of at least one solar active region, but with improved resolution, a larger field of view and increased effective area. Here we present the updated instrument layout, the expected performance, the integration and calibration approach, and proposed future improvements, including the implementation of additional complimentary spectral diagnostics.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument designed and built to observe X-ray emissions from the Sun’s atmosphere in the 6–24Å (0.5–2.0keV) range while achieving high spectral and spatial resolution along a 8-arcminute long slit. We describe the alignment process and discuss the results achieved for assembling the Telescope Mirror Assembly (TMA) and the Spectrometer Optics Assembly (SOA) prior to final integration into the MaGIXS instrument. The MaGIXS mirrors are full shell, electroformed nickel replicated on highly polished mandrels at the Marshall Space Flight Center (MSFC). The TMA carries a single shell, Wolter Type-1 mirror pair (primary and secondary) formed on a common mandrel. The SOA includes a matched pair of identical parabolic mirrors and a planar varied-line spacing (VLS) diffraction grating. We performed the subassembly alignment and mounting at the Smithsonian Astrophysical Observatory (SAO) using metrology and precision positioning systems constructed around the Centroid Detector Assembly (CDA), originally built for the alignment of the Chandra mirror shells. The MaGIXS instrument launch has been postponed until 2021 due to the COVID-19 pandemic.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument designed to obtain spatially resolved soft X-ray spectra of the solar atmosphere in the 6–24 Å (0.5–2.0 keV) range. The instrument consists of a single shell Wolter Type-I telescope, a slit, and a spectrometer comprising a matched pair of grazing incidence parabolic mirrors and a planar varied-line space diffraction grating. The instrument is designed to achieve a 50 mÅ spectral resolution and 5 arcsecond spatial resolution along a ±4-arcminute long slit, and launch is planned for 2019. We report on the status and our approaches for fabrication and alignment for this novel optical system. The telescope and spectrometer mirrors are replicated nickel shells, and are currently being fabricated at the NASA Marshall Space Flight Center. The diffraction grating is currently under development by the Massachusetts Institute of Technology (MIT); because of the strong line spacing variation across the grating, it will be fabricated through e-beam lithography.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument designed to obtain spatially resolved soft X-ray spectra of the solar atmosphere in the 6–24 Å (0.5–2.0 keV) range. The instrument consists of a single shell Wolter Type-I telescope, a slit, and a spectrometer comprising a matched pair of grazing incidence parabolic mirrors and a planar varied-line space diffraction grating. The instrument is designed to achieve a 50 mÅ spectral resolution and 5 arcsecond spatial resolution along a ±4-arcminute long slit, and launch is planned for 2019. We report on the status and our approaches for fabrication and alignment for this novel optical system. The telescope and spectrometer mirrors are replicated nickel shells, and are currently being fabricated at the NASA Marshall Space Flight Center. The diffraction grating is currently under development by the Massachusetts Institute of Technology (MIT); because of the strong line spacing variation across the grating, it will be fabricated through e-beam lithography.
Jenna Samra, Peter Cheimets, Edward DeLuca, John Galeros, Thomas Gauron, Leon Golub, Giora Guth, Edward Hertz, Philip Judge, Serge Koutchmy, Vanessa Marquez
This paper presents the design of an innovative solar spectrometer that will y on the NSF/NCAR Gulfstream V High-Performance Instrumented Airborne Platform for Environmental Research (GV HIAPER) during the 2017 solar eclipse. The airborne infrared spectrometer (AIR-Spec) is groundbreaking in two aspects: it will image infrared coronal emission lines that have never been measured, and it will bring high resolution imaging to GV HIAPER. The instrument development faces the challenges of achieving adequate resolution and signal-to-noise ratio in a compact package mounted to a noisy moving platform. To ensure that AIR-Spec meets its research goals, the instrument is undergoing pre-flight modeling and testing. The results are presented with reference to the instrument requirements.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument that is designed to observe soft X-ray emissions from 24 - 6.0 Å (0.5 - 2.0 keV energies) in the solar atmosphere. For the first time, high-temperature, low-emission plasma will be observed directly with 5 arcsecond spatial resolution and 22 mÅ spectral resolution. The unique optical design consists of a Wolter - I telescope and a 3-optic grazing- incidence spectrometer. The spectrometer utilizes a finite conjugate mirror pair and a blazed planar, varied line spaced grating, which is directly printed on a silicon substrate using e-beam lithography. The grating design is being finalized and the grating will be fabricated by the Massachusetts Institute of Technology (MIT) and Izentis LLC. Marshall Space Flight Center (MSFC) is producing the nickel replicated telescope and spectrometer mirrors using the same facilities and techniques as those developed for the ART-XC and FOXSI mirrors. The Smithsonian Astrophysical Observatory (SAO) will mount and align the optical sub-assemblies based on previous experience with similar instruments, such as the Hinode X-Ray Telescope (XRT). The telescope and spectrometer assembly will be aligned in visible light through the implementation of a theodolite and reference mirrors, in addition to the centroid detector assembly (CDA) - a device designed to align the AXAF-I nested mirrors. Focusing of the telescope and spectrometer will be achieved using the X-ray source in the Stray Light Facility (SLF) at MSFC. We present results from an alignment sensitivity analysis performed on the on the system and we also discuss the method for aligning and focusing MaGIXS.
Ken Kobayashi, Jonathan Cirtain, Amy Winebarger, Sabrina Savage, Leon Golub, Kelly Korreck, Sergey Kuzin, Robert Walsh, Craig DeForest, Bart DePontieu, Alan Title, William Podgorski, Ryouhei Kano, Noriyuki Narukage, Javier Trujillo-Bueno
We present an overview of solar sounding rocket instruments developed jointly by NASA Marshall Space Flight Center
and the University of Alabama in Huntsville. The High Resolution Coronal Imager (Hi-C) is an EUV (19.3 nm) imaging
telescope which was flown successfully in July 2012. The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a
Lyman Alpha (121.6 nm) spectropolarimeter developed jointly with the National Astronomical Observatory of Japan and
scheduled for launch in 2015. The Marshall Grazing Incidence X-ray Spectrograph is a soft X-ray (0.5-1.2 keV) stigmatic
spectrograph designed to achieve 5 arcsecond spatial resolution along the slit.
NASA/MSFC and SAO have developed a High Resolution EUV Solar Coronal Imaging telescope (Hi-C). The scientific objective of the mission is to determine, at higher spatial resolution than previously available, the geometric configuration and topology of the structures making up the inner corona. The Hi-C telescope launched on a rocket in early July 2012. It acts as a technology pathfinder for future satellite based missions. Key technology features of the Hi-C telescope are: (1) A 23.9 meter focal length, allowing for 0.1 arc-second pixels (2) Extremely high quality optics (3) Single wavelength multi-layer coating over the entire surface of each optic (4) Low distortion approach to mounting the primary into the telescope. The low distortion approach to mounting the primary mirror into the telescope is discussed in this paper. In previous solar EUV telescopes (TRACE, AIA, IRIS) the primary mirror is first bonded into a flexured mirror cell that is then bolted into the telescope. Techniques for bonding the mirror into the mirror cell have been well developed. If done properly, these techniques produce minimal distortion in the optic. Experience has shown, however, that bolting of the cell into the telescope produces distortions, typically in the form of astigmatism. The magnitude of the astigmatism may be acceptable for lower resolution missions, but as we approach ever higher resolutions, these astigmatisms contribute significantly to the error budget. In the Hi-C mission the mirror mounting hardware was completely assembled into the telescope tube prior to bonding the mirror to the mount. This final operation was done with the telescope tube vertical and the primary mirror surface facing up. This approach minimizes the "bolt-up" distortions typically seen, thus improving resolution.
Experimental multilayer reflectance data on flight mirrors and witnesses for three extreme ultraviolet (EUV) channels of
the Atmospheric Imaging Assembly (AIA) instrument aboard NASA’s Solar Dynamics Observatory are presented and
compared to theoretical models. The relevance of these results to the performance of the AIA instrument is discussed.
The Interface Region Imaging Spectrograph (IRIS) is a NASA SMall EXplorer mission scheduled for launch in January
2013. The primary goal of IRIS is to understand how the solar atmosphere is energized. The IRIS investigation
combines advanced numerical modeling with a high resolution UV imaging spectrograph. IRIS will obtain UV spectra
and images with high resolution in space (0.4 arcsec) and time (1s) focused on the chromosphere and transition region of
the Sun, a complex interface region between the photosphere and corona. The IRIS instrument uses a Cassegrain
telescope to feed a dual spectrograph and slit-jaw imager that operate in the 133-141 nm and 278-283 nm ranges. This
paper describes the instrument with emphasis on the imaging spectrograph, and presents an initial performance
assessment from ground test results.
This paper discusses the design of the IRIS Small Explorer (SMEX) Cassegrain telescope, as well as its intended and measured
performance. Lockheed Martin, along with SAO, Montana State University, and Stanford University are developing
the IRIS instrument for a mission to examine the solar spectra in two bands, one centered on 1369 Å, and the other centered
on 2810 Å. SAO led the design and construction of the telescope feed, with assistance from Lockheed and Montana State
University.
The telescope posed a number of implementation challenges, which are discussed here, including the fact that no effective
filters exist to isolate the science spectra to the exclusion of the rest of the solar flux, making it necessary to allow full
sunlight into the telescope.
The Marshall Grazing Incidence X-ray Spectrograph (MaGIXS) is a proposed sounding rocket experiment designed to observe
spatially resolved soft X-ray spectra of the solar corona for the first time. The instrument is a purely grazing-incidence
design, consisting of aWolter Type-1 sector telescope and a slit spectrograph. The telescope mirror is a monolithic Zerodur
mirror with both the parabolic and hyperbolic surfaces. The spectrograph comprises a pair of paraboloid mirrors acting as
a collimator and reimaging mirror, and a planar varied-line-space grating, with reflective surfaces operate at a graze angle
of 2 degrees. This produces a flat spectrum on a detector covering a wavelength range of 6-24Å (0.5-1.2 keV). The design
achieves 20 mÅ spectral resolution (10 mÅ /pixel) and 5 arcsec spatial resolution (2.5 arcsec / pixel) over an 8-arcminute
long slit. The spectrograph is currently being fabricated as a laboratory prototype. A flight candidate telescope mirror is
also under development.
We present the design for a stigmatic grazing incidence X-ray spectrograph designed for solar coronal observations. The
spectrograph is composed of a slit, a pair of paraboloid mirrors and a plano varied-line-space grating. All reflective surfaces
of the spectrograph operate at an angle of incidence of 88 degrees, and covers a wavelength range of 0.6 to 2.4nm (0.5 to
2.0keV). The design achieves 1.5pm spectral resolution and 15 μm spatial resolution over a 2.5mmlong slit. The current
spectrograph design is intended for a sounding rocket experiment, and designed to fit inside a NASA sounding rocket
payload behind a 1.1m focal length Wolter Type-1 telescope. This combination will have a 2.5arcsec spatial resolution
and a 8 arcminute slit length. We are currently fabricating a laboratory prototype of the spectrograph to demonstrate the
performance and establish the alignment procedures for a flight model.
We present experimental results on the development and testing of the extreme ultraviolet (EUV) reflective multilayer coatings that will be used in the Atmospheric Imaging Assembly (AIA) instrument. The AIA, comprising four normal incidence telescopes, is one of three instruments aboard the Solar Dynamics Observatory mission, part of NASA's Living with a Star program, currently scheduled for launch in 2008. Seven different multilayer coatings will be used, covering the wavelength region from 93.9 to 335.4 Å.
Hot magnetized plasmas - typified by the solar corona - are ubiquitous throughout the universe. The physics governing the dynamics of such plasmas takes place on remarkably small spatial and temporal scales, while both the cause activity and the response occur on large spatial scales. Thus both high resolution and large fields of view are needed. Observations from SMM, Yohkoh, EIT and TRACE show that typical solar active region structures range in temperature from 0.5 to 10 MK, and up to 40MK in flares, implying the need for broad temperature coverage. The RAM S-T Probe consists of a set of imaging and spectroscopic instruments that will enable definitive studies of fundamental physical processes that govern not only the solar atmosphere but much of the plasma universe. Few problems in astrophysics have proved as resistant to solution as the microphysics that results in the production of high-energy particles in hot magnetized plasmas. Theoretical models have focused in recent years on the various ways in which energy may be transported to the corona, and there dissipated, through the reconnection of magnetic fields. Theory implies that the actual dissipation of energy in the corona occurs in spatially highly localized regions, and there is observational support for unresolved structures with filling factors 0.01 - 0.001 in dynamic coronal events.
The Solar-B X-ray telescope (XRT) is a grazing-incidence modified Wolter I X-ray telescope, of 35 cm inner diameter and 2.7 m focal length. XRT, designed for full sun imaging over the wavelength 6-60 Angstroms, will be the highest resolution solar X-Ray telescope ever flown. Images will be recorded by a 2048 X 2048 back-illuminated CCD with 13.5 μm pixels (1 arc-sec/pixel ) with full sun field of view. XRT will have a wide temperature sensitivity in order to observe and discriminate both the high (5-10 MK) and low temperature (1-5 MK) phenomena in the coronal plasma.
This paper presents preliminary results of the XRT mirror calibration performed at the X-ray Calibration Facility, NASA-MSFC, Huntsville, Alabama during January and February 2005. We discuss the methods and the most significant results of the XRT mirror performance, namely: characteristics of the point response function (PSF), the encircled energy and the effective area. The mirror FWHM is 0.8" when corrected for 1-g, finite source distance, and CCD pixelization. With the above corrections the encircled energy at 27 μm and 1keV is 52%. The effective area is greater than 2cm2 at 0.5keV and greater than 1.7cm2 at 1.0keV.
We present scientific as well as engineering overview of the X-Ray Telescope (XRT) aboard the Japanese Solar-B mission to be launched in 2006, with emphasis on the focal plane CCD camera that employs a 2k x 2k back-thinned CCD. Characterization activities for the flight CCD camera made at the National Astronomical Observatory of Japan (NAOJ) are discussed in detail with some of the results presented.
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite SOLAR-B (launch in 2006) is equipped with a modified Wolter I grazing incidence X-ray telescope (focal length 2700 mm) to image the full Sun at ~ 1.5" angular resolution onto a 2048 x 2048 back illuminated CCD focal plane detector. The X-ray telescope consisting of one single reflecting shell is coated with ion beam sputtered Iridium over a binding layer of Chromium to provide nearly 5 square centimetres effective area at 60 Å. We present preliminary results of X-ray calibrations of the XRT flat mirror samples performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. We describe the instrumental set-up, the adopted measurement technique, and present the measured reflectivity vs. angle of incidence at few energies.
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite
SOLAR-B (launch in 2006) aimed at providing full Sun field of view at
~ 1.5" angular resolution, will be equipped with two wheels of focal-plane filters to select spectral features of X-ray emission from the Solar corona, and a front-end filter to significantly reduce the visible light contamination. We present the results of the X-ray calibrations of the XRT flight filters performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. We describe the instrumental set-up, the adopted measurement technique, and present the transmission vs. energy and position measurements.
We present an overview of currently available EUV multilayer coatings that can be used for the construction of solar physics instrumentation utilizing normal-incidence optics. We describe the performance of a variety of Si-based multilayers, including Si/B4C and new Si/SiC films that provide improved performance in the wavelength range from 25 n 35 nm, as well as traditional Si/Mo multilayers, including broad-band coatings recently developed for the Solar-B/EIS instrument. We also outline prospects for operation at both longer and shorter EUV wavelengths, and also the potential of ultra-short-period multilayers that work near normal incidence in the soft X-ray region.
A hot, magnetized plasma such as the solar corona has the property that much of the physics governing its activity takes place on remarkably small spatial and temporal scales, while the response to this activity occurs on large scales. Observations from SMM, TRACE, SOHO and Yohkoh have shown that typical solar active regions have loops ranging in temperature from 0.5 to 10 MK, and flares up to 40MK. The spatial and temporal domains involved have been heretofore inaccessible to direct observations from Earth, so that theory has relied heavily on extrapolations from more accessible regimes, and on speculation. The RAM Solar-Terrestrial Probe consists of a set of carefully selected imaging and spectroscopic instruments that enable definitive studies of the dynamics and energetics of the solar corona.
The X-ray observations from the Yohkoh SXT provided the greatest step forward in our understanding of the solar corona in nearly two decades. We believe that the scientific objectives of the Solar-B mission can best be achieved with an X-ray telescope (XRT) similar to the SXT, but with significant improvements in spatial resolution and in temperature response that take into account the knowledge gained from Yohkoh. We present the scientific justification for this view, discuss the instrumental requirements that flow from the scientific objectives, and describe the instrumentation that will meet these requirements. XRT is a grazing-incidence (GI) modified Wolter I X-ray telescope, of 35 cm inner diameter and 2.7 m focal length. The 2048 X 2048 back-illuminated CCD has 13.5 (mu) pixels, corresponding to 1.0 arcsec and giving full Sun field of view. This will be the highest resolution GI X-ray telescope ever flown for Solar coronal studies, and it has been designed specifically to observe both the high and low temperature coronal plasma.
The Advanced Solar Coronal Explorer (ASCE) is one of five missions selected for a Phase A Concept Study in the current round of proposed MIDEX missions. ASCE's instrument complement is supported by a SPARTAN 400 reusable carrier. The spacecraft is carried into orbit and deployed by the Space Shuttle; at mission's end, nominally 2 years later, it is retrieved and returned to earth for post-flight calibration. ASCE comprises two instrument modules, the Spectroscopic and Polarimetric Coronagraph (SPC) and the Extreme Ultraviolet Imager (EUVI). The external occulter for the coronagraph is supported on a boom, which is extended 10 meters beyond the instrument apertures once the spacecraft is on station. Large aperture optics can therefore be used, and this, in combination with improvements in optical and photon detection efficiencies, will provide spectroscopy of the extended solar corona with unprecedented sensitivity and spatial resolution, routine measurements of the electron temperature, and polarimetry of the H I Lyman lines. SPC also extends the short wavelength limit to 28 nm. As a consequence, SPC will be able to perform the first He II 30.4 nm and He I 58.4 nm spectroscopy of the extended corona. In the visible part of the spectrum (450 - 600 nm), SPC's Large Aperture Spectroscopic Coronagraph (LASCO) channel will provide polarimetric images with 1.8 arc second resolution elements, which will allow the determination of polarized brightness of the coronal plasma. In a separate parallel channel LASCO will also provide images at single minor ion line wavelengths from which can be determined the shapes and Doppler shifts of those lines. The distant external occulter provides for major improvement in stray light suppression. The EUVI instrument will take high cadence images of the full disk and low corona at four selectable wavelengths with 0.9 arc second resolution elements. A description of the instrument design and performance capabilities is presented.
The process of observing the Sun in the x-ray and extreme UV (XUV), as we are now doing with the TRACE telescope, requires blocking the tremendous amount of visible and RI light that dominates the flux from the sun. If it is not blocked, the energy will swamp the desired spectrum and cause thermal problems inside the telescope. The most effective approach removing the energy is by filtering the incoming light. One of the best materials for eliminating the undesirable wavelengths is aluminum, which is semi- transparent to x-ray and XUV, but blocks most light with wavelength redward of 850 angstrom. Unfortunately the aluminum must be extremely must be extremely thin, < 1600 angstrom thick, to provide the necessary XUV transparency. To overcome the structural problem of supporting large areas of extremely thin aluminum, the aluminum film is bonded on a nickel mesh.
Orbiting x-ray and XUV observatories are pushing the achievable image resolution and with it, the requirements on mounted mirror performance. The transitional region and coronal explorer (TRACE) observatory uses a center mounted primary mirror that must maintain its orientation in roll as well as pitch and way. A conformable bedding was used to support the mirror against the expected launch loads in a re-assembled mount, without inducing unacceptable mirror distortion. The novel mirror mount design is discussed, and its resulting performance described. This paper outlines the TRACE primary mirror assembly design. The evolution of the design from the Space Weather and Terrestrial Hazards assembly to the TRACE baseline design is presented.
This paper describes the conceptual design of a soft x-ray telescope, super-x, which we will propose for the Japan/US/UK Solar-B mission. Super-X will break new ground in both angular resolution and solar coronal temperature discrimination. The telescope design is based upon the successful transition region and coronal explorer instrument. It features four XUV spectral channels spanning the 0.3 to 20 MK temperature range with an angular resolution of approximately 0.27 seconds of arc. We will describe considerations affecting spectral line selection and some details of the characteristics of the instrument.
HIREX is a suite of three complementary solar-pointed instruments that is being proposed to NASA under the NASA MIDEX announcement of opportunity. The main instrument is a 0.6m clear aperture, 240m effective focal length normal incidence XUV telescope operated at 171 angstrom, with a spatial resolution of 0.01 inch. This main telescope is complemented by two other instruments: 1) a 0.3 m context telescope that images in a wavelength range that covers the UV and XUV spectral regime, based on the TRACE design. This context telescope places the high magnification, limited field of view images created by the high resolution telescope in both spatial and temperature context. 2) A spectrometer covering the spectral range from 170-220 angstrom, based on the SERTS design.
The proposed HELIX mission consists of two spacecraft that will enable stereoscopic imaging of solar mass ejections, starting with their origins on the Sun and continuing to 1 AU and beyond. With a complement of telescopes and plasma detectors, the HELIX spacecraft will test magnetic helicity conservation and other approaches to understanding the physics of solar mass ejections. The mission will help explain how and why solar ejections occur and how they evolve in interplanetary space. 3D images and velocity maps and in-situ space plasma and magnetic field measurements will allow identification and tracking of ejected plasma. Detection of eruptions aimed at Earth will be an immediate practical benefit of the mission. The HELIX mission should lead to the development of a reliable storm prediction capability that will be of significant value to communications systems operators, electric power networks, NASA operators and others.
We have produced two new normal incidence soft x-ray telescope mirrors coated for lambda equals 63.5 angstrom wavelength: the first with a focal length f equals 1.5 m and a diameter of 25 cm for the Space Weather and Terrestrial Hazards (SWATH) satellite and the second (f equals 2 m, diameter 27.5 cm) for launch by sounding rocket (NIXT). We describe figuring and polishing of the mirror surfaces and deposition and testing of the multilayer coatings. Optimization of the mirror fabrication included grazing incidence x-ray reflectivity for quality control during polishing. In addition, the substrate and each metal layer of the Co-C multilayer coating were polished by an ion beam with in-situ roughness estimation. We explored the possibilities and limitations of telescopes for shorter wavelengths by coating several small mirrors covering the lambda equals 45 to 60 angstrom region at normal incidence and report on their performance.
The instruments on board our Normal Incidence X-ray Telescopes payload and the results obtained during the most recent flights will be described. The payload was launched three times during the 1991 - 1993 period, the last time on April 12, 1993. It contained a main telescope with an 11 inch diameter multilayer coated mirror for (lambda) equals 63.5 angstroms and photographic film as detector. Smaller telescopes for either (lambda) equals 304 angstroms or (lambda) equals 193 angstroms used electronic detection and direct transmission of analog or digital data to the ground station. The flight on the day of the solar eclipse in July 1991 gave us an opportunity to perform a soft-ray knife edge test with the limb of the moon. From the experiment we derive upper limits for the figure errors of the telescope mirror, and we conclude that large mirrors with diffraction limited resolution better than 0.01 arcsec can now be fabricated.
Photos obtained during 5 mm of observation time from the flight of our 25-cm-diam normal-incidence soft x-ray (λ = 63.5 Å) telescope on September 11, 1989, are analyzed and the data are compared to the results expected from tests of the mirror surfaces. These tests cover a range of spatial periods from 25 cm to 1 Å. The photos demonstrate a resolution close to the photon shot noise limit and a reduction in the scattering of the multilayer mirror compared to a single surface for scattering angles above 1 arcmin, corresponding to surface irregularities with spatial penods below 10 μm. Our results are used to predict the possible performance of future telescopes: We conclude that sounding rocket observations might be able to reach a resolution around 0.1 arcsec. Higher resolutions will require flights of longer durations and improvements in mirror testing for the largest spatial periods.
Photos obtained during 5 mm. of observation time from the flight of our 10 inch normal incidence
soft x-ray (1 = 63.5A) telescope on September 11, 1989 are analyzed and the data are compared to the
results expected from tests of the mirror surfaces. These tests cover a range of spatial periods from 25
cm to lÅ. The photos demonstrate a reduction in the scattering of the multilayer mirror compared to
a single surface for scattering angles above 1 arcmin, corresponding to surface irregularities with spatial
periods below 10 tim. Our results are used to predict the possible performance of future flights.
Sounding rocket observations might be able to reach a resolution around 0. 1 arcsec. Higher resolutions
will require flights of longer durations and improvements in mirror testing for the largest spatial penods.
Soft x-ray telescopes require filters that block visible and infrared light and have good soft x-ray transmission. The optical properties of possible materials are discussed, and the fabrication and testing methods for the filters used in a 10-inch normal incidence telescope for X = 63 A are described. The best performances in the is. 44-1 14 A wavelength range are obtained with foils of carbon and rhodium.
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.