This paper will describe the scientific goals of our sounding rocket program, the Solar Ultraviolet Magnetograph
Investigation (SUMI). This paper will present a brief description of the optics that were developed to meet SUMI's
scientific goals, discuss the spectral, spatial and polarization characteristics of SUMI's optics, describe SUMI's flight
which was launched 7/30/2010, and discuss what we have learned from that flight.
This paper will describe the Marshall Space Flight Center's Solar Ultraviolet Magnetograph (SUMI) sounding rocket
program, with emphasis on the polarization characteristics of the VUV optics and their spectral, spatial and polarization
resolution. SUMI's first flight (7/30/2010) met all of its mission success criteria and this paper will describe the data
that was acquired with emphasis on the MgII linear polarization measurements.
This paper describes the scientific goals of a sounding rocket program called the Solar Ultraviolet Magnetograph Investigation (SUMI), presents a brief description of the optics that were developed to meet those goals and discusses the spectral, spatial and polarization characteristics of SUMI's Toroidal Variable-Line-Space (TVLS) gratings, which are critical to SUMI's measurements of the magnetic field in the Sun's transition region.
Toroidal variable-line-space (VLS) gratings are very important in the design of an efficient VUV solar telescope that will measure the CIV (155nm) and MgII (280nm) emissions lines in the Sun's transition region. In 1983 Kita and Harada described spherical VLS gratings but the technology to commercially fabricate these devices is a recent development, especially for toroidal surfaces. This paper will describe why this technology is important in the development of the Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket program (the good), the delays due to the conversion between the TVLS grating design and the optical fabrication (the bad), and finally the optical testing, alignment and tolerancing of the gratings (the ugly).
Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry-Pérot Interferometer that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry Pérot.
We describe an evolutionary algorithm for the design of an imaging triple-étalon Fabry-Perót interferometer (MFPI), which gives a solution to the multidimensional minimization process through a stochastic search method. The interactions between design variables (the étalon reflectances, interétalon ghost attenuator transmittances, and spacing ratios) are complex, resulting in a fitness landscape that is pitted with local optima. Traditional least-squares and gradient descent algorithms are not useful in such a situation. Instead, we employ a method called evolution strategies in which several preliminary designs are randomly generated subject to constraints. These designs are combined in pairs to produce offspring designs. The offspring population is mutated randomly, and only the fittest designs of the combined population are passed to the next iteration of the evolutionary process. We discuss the evolution strategies method itself, as well as its application to the specific problem of the design of an incoherently coupled triple-étalon interferometer intended for use as a focal plane instrument in the planned National Solar Observatory's Advanced Technology Solar Telescope (NSO's ATST). The algorithm converges quickly to a reasonable design that is well within the constraints imposed on the design variables, and which fulfills all resolution, signal-to-noise, throughput, and parasitic band suppression requirements.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph
Investigation (SUMI) and the unique optical components that have been developed to meet those objectives. A sounding
rocket payload has been developed to test the feasibility of magnetic field measurements in the Sun's transition region.
The optics have been optimized for simultaneous measurements of two magnetic sensitive lines formed in the transition
region (CIV at 1550 Å and MgII at 2800 Å). This paper will concentrate on the polarization properties SUMI's toroidal
varied-line-space (TVLS) gratings and its system level testing as we prepare to launch in the Summer of 2008.
We present measurements of toroidal variable-line-space (TVLS) gratings for the Solar Ultraviolet Magnetograph
Investigation (SUMI), currently being developed at the National Space Science and Technology Center (NSSTC).
SUMI is a spectro-polarimeter designed to measure magnetic fields in the solar chromosphere by observing two UV
emission lines sensitive to magnetic fields, the CIV line at 155nm and the MgII line at 280nm. The instrument uses a
pair of TVLS gratings, to observe both linear polarizations simultaneously. Efficiency measurements were done on
bare aluminum gratings and aluminum/MgF<sub>2</sub> coated gratings, at both linear polarizations.
We present four preliminary designs for a telecentric optical train supporting the Advanced Technology Solar Telescope (ATST) multiple Fabry-Pérot interferometer (MFPI), which is to be used as an imaging spectrometer and imaging spectropolarimeter. The point of departure for all three designs is the F/40 telecentric image at the Coudé focus of the ATST. The first design, representing the high-spectral-resolution mode of operation, produces an intermediate F/300 telecentric image within the triple étalon system and a 34-arcsec field of view (FOV). The second design, intermediate between high- and low-spectral-resolution modes of operation, produces an intermediate F/150 telecentric image at the étalons and a 1.1-arcmin FOV. The third and fourth designs each represent a low-resolution mode of operation, producing an F/82 telecentric image at the étalons and a 2-arcmin FOV. Each design results in good telecentricity and image quality. Departures from telecentricity at the intermediate image plane cause field-dependent shifts of the bandpass peak, which are negligible compared to the bandpass FWHM. The root mean square (rms) geometric spot sizes at the final image plane fit well within the area of a camera pixel, which is itself in accordance with the Nyquist criterion, half the width of the 28-µm-wide resolution element (as determined from the diffraction limit of the ATST). For each configuration, we also examine the impact that the Beckers effect (the pupil apodization caused by the angle-dependent amplitude transmittance of the MFPI) has on the image quality of the MFPI instrument.
The Magnetic Transition Region Probe is a space telescope designed to measure the magnetic field at several heights and temperatures in the solar atmosphere, providing observations spanning the chromospheric region where the field is expected to become force free. The primary goal is to provide an early warning system (hours to days) for solar energetic particle events that pose a serious hazard to astronauts in deep space and to understand the source regions of these particles. The required magnetic field data consist of simultaneous circular and linear polarization measurements in several spectral lines over the wavelength range from 150 to 855 nm. Because the observations are photon limited an optical telescope with a large (>18m<sup>2</sup>) collecting area is required. To keep the heat dissipation problem manageable we have chosen to implement MTRAP with six separate Gregorian telescopes, each with ~ 3 m<sup>2</sup> collecting area, that are brought to a common focus. The necessary large field of view (5 × 5 arcmin<sup>2</sup>) and high angular resolution (0.025 arcsec pixels) require large detector arrays and, because of the requirements on signal to noise (10<sup>3</sup>), pixels with large full well depths to reduce the readout time and improve the temporal resolution. The optical and engineering considerations that have gone into the development of a concept that meets MTRAP's requirements are described.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. A sounding rocket payload is being developed to test the feasibility of magnetic field measurements in the Sun's transition region. The optics have been optimized for simultaneous measurements of two magnetic lines formed in the transition region (CIV at 1550Å and MgII at 2800Å). Finally, this paper will concentrate on the polarization properties of the SUMI polarimeter and toroidal variable-line-space gratings.
This paper will describe the evolution of the Marshall Space Flight Center's (MSFC) electro-optical polarimeter with emphasis on the field-of-view characteristics of the KD*P modulator. Understanding those characteristics was essential to the success of the MSFC solar vector magnetograph. The paper will show how the field-of-view errors of KD*P look similar to the linear polarization patterns seen in simple sunspots and why the placement of the KD*P in a collimated beam was essential in separating the instrumental polarization from the solar signal. Finally, this paper will describe a modulator design which minimizes those field-of-view errors.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. In order to test the scientific feasibility of measuring magnetic fields in the UV, a sounding rocket payload is being developed. This paper will discuss: (1) the scientific measurements that will be made by the SUMI sounding rocket program, (2) how the optics have been optimized for simultaneous measurements of two magnetic lines CIV (1550Å) and MgII (2800Å), and (3) the optical, reflectance, transmission and polarization measurements that have been made on the SUMI telescope mirrors and polarimeter.
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.
We outline here a preliminary optical design study for a telecentric tunable Fabry-Perot etalon system. The first result of the optical optimization into a design, which delivers performance image quality and telecentricity, is presented here. Bearing in mind the possible use of such a study design - as a possible instrument for the Advanced Technology Solar Telescope (ATST) - we also show that a hybrid design strategy delivers a compact design that will fit inside the ATST's Coude optical tables.
Multiple etalon systems are discussed that meet the science requirements for a narrow-passband imaging system for the 4-meter National Solar Observatory (NSO)/Advance Technology Solar Telescope (ATST). A multiple etalon system can provide an imaging interferometer that works in four distinct modes: as a spectro-polarimeter, a filter-vector magnetograph, an intermediate-band imager, and broadband high-resolution imager. Specific dual and triple etalon configurations are described that provide a spectrographic passband of 2.0-3.5 pm and reduce parasitic light levels to 10<sup>-4 </sup>as required for precise polarization measurement, e.g., Zeeman measurements of magnetic sensitive lines. A TESOS-like (Telecentric Etalon SOlar Spectrometer) triple etalon system provides a spectral purity of 10<sup>-5</sup>. The triple designs have the advantage of reducing the finesse requirement on each etalon; allow the use of more stable blocking filters, and have very high spectral purity. A dual-etalon double-pass (Cavallini-like) system can provide a competing configuration. Such a dual-etalon design can provide high contrast. The selection of the final focal plane instrument will depend on a trade-off between an ideal instrument and practical reality. The trade study will include the number of etalons, their aperture sizes, complexities of the optical train, number of blocking filters, configuration of the electronic control system, computer interfaces, temperature controllers, etalon controllers, and their associated feedback electronics. The heritage of single and multiple etalon systems comes from their use in several observatories, including the Marshall Space Flight Center (MSFC) Solar Observatory, Sacramento Peak Observatory (NSO), and Kiepenheuer-Institut für Sonnenphysik (KIS, Germany), Mees Solar Observatory (University of Hawaii), and Arcetri Astrophysical Observatory (Italy). The design of the ATST multiple etalon system will benefit from the experience gained at these observatories.
This paper will describe a new vector magnetograph that has been developed at Marshall Space Flight Center. This magnetograph was a test ed for space flight concepts. One of those concepts that is currently being tested is the increased sensitivity to linear polarization by replacing electro-optical and rotating waveplates with a rotating linear analyzer. Our paper will describe the motivation for developing this magnetograph, compare this instrument with traditional magnetograph designs.
The polarizing optics that are being developed for the Solar UV Magnetograph Investigation (SUMI) are described. This polarimeter is being designed for a sounding rocket payload which will make simultaneous measurements of two magnetically sensitive lines CIV and MgII. With a limited observing program, the polarizing optics will be optimized for circular and linear polarization measurements in active regions. The Q polarization will represent exploratory measurements of the transverse field in strong sunspots. This paper will give a brief overview of the SUMI instrument and its scientific goals, will describe the polarimeter that will be used in the sounding rocket program, and will present some of the measurements that have been made on the SUMI polarization optics.
This paper will describe the scientific objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. In order to test the scientific feasibility of measuring magnetic fields in the UV, a sounding rocket payload is being developed. This paper will discuss: (1) the scientific measurements that will be made by the SUMI sounding rocket program, (2) how the optics have been optimized for simultaneous measurements of two magnetic lines CIV (1550 Angstroms) and MgII (2800 Angstroms), and (3) the optical, reflectance, transmission and polarization measurements that have been made on the SUMI telescope mirrors and polarimeter.
Traditional magnetographs measure the solar magnetic field at the visible 'surface' of the Sun, the photosphere. The Solar Ultraviolet Magnetograph Investigation (SUMI) is a hardware development study for an instrument to measure the solar magnetic field higher in the atmosphere, in the upper chromosphere and in the transition region at the base of the corona. The magnetic pressure at these levels is much stronger than the gas pressure (in contrast to the situation at the photosphere), so the field controls the structure and dynamics of the atmosphere. Rapid changes in the magnetic structure of the atmosphere become possible at this height, with the release of energy. Measurements of the vector magnetic field in this region will significantly improve our understanding of the physical processes heating the Sun's upper atmosphere and driving transient phenomena such as flares and coronal mass ejections. The instrument will incorporate new technologies to achieve the polarization efficiencies required to measure the magnetic splitting of lines in the VUV an UV (C<SUB>IV</SUB> at 1550 angstrom and Mg<SUB>II</SUB> at 2800 angstrom). We describe the scientific goals, the optical components that are being developed for a sounding rocket program, and the SUMI baseline design.
Pulsed-laser deposition has proved to be a promising method for producing complex inorganic thin films. One of its major advantages, relative to other methods, is the capability of controlling many process parameters, such as laser pulse width, energy, and wavelength along with background reactive gas pressure and substrate bias. Adjusting these parameters provides a pre-tuning of the laser plasma thereby allowing for optimum process conditions in a particular thin film deposition. Understanding and fully characterizing such highly-dynamic and rapidly-streaming plasmas requires multiple techniques for monitoring the plasmas at different stages. By combining different diagnostic methods, it is possible to analyze the broad time window over which these ablation plasmas develop and to understand the related processes that occur. We present in this work new results involving correlation of time-resolved Langmuir probe data, optical emission spectroscopy, and electrostatic energy analysis to characterize the laser-induced plasmas generated from targets of titanium, tin-dioxide and aluminum. Two laser sources, an 80 fs Ti:Sapphire laser (780 nm) and a 6 ns Nd:YAG laser (1.06 micrometer), were used in this work. Examples of very high quality, epitaxial tin-dioxide films grown on sapphire by femtosecond-laser MBE are presented. These films are evaluated by high-resolution, cross-sectional TEM and x-ray diffraction. Film quality is considered in relation to the ablation plasma parameters, wherein femtosecond and nanosecond plasmas are compared.
Studies of the 3D structure and dynamics of the solar corona have been severely limited by the constraint of single viewpoint observations. The Stereo X-Ray Coronal Imager (SXCI) mission will send a single instrument, an X-ray telescope, into deep space expressly to record stereoscopic images of the solar corona. The SXCI spacecraft will be inserted into an approximately 1 ZAU heliocentric orbit leading Earth by approximately 25 degrees at the end of nine months. The SXCI x-ray telescope forms one element of a stereo pair, the second element being an identical x-ray telescope in Earth orbit placed there as part of the NOAA GOES program. X-ray emission is a powerful diagnostic of the corona and its magnetic fields, and 3D information on the coronal magnetic structure would be obtained by combining the data from the two x-ray telescopes. This information can be used to address the major solar physics questions of (1) what causes explosive coronal events such as coronal mass ejections, eruptive flares and prominence eruptions and (2) what causes the transient heating of coronal loops. Stereoscopic views of the optically thin corona will resolve some ambiguities inherent in single line-of-sight observations. Triangulation gives 3D solar coordinates of features which can be seen in the simultaneous images form both telescopes. As part of this study, tools were developed for determining the 3D geometry of coronal features using triangulation. Advanced technologies for visualization and analysis of stereo images were tested. Results of mission and spacecraft studies are also reported.