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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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This paper provides an overview of the architecture, design, integration, and test of the SIM flight interferometer real time control to meet challenging flight system requirements for the high processor throughput, low-latency interconnect, and precise synchronization to support microarcsecond-level astrometric measurements for greater than five years at 1 AU in Earth-trailing orbit.
We describe the differential phase mode of the Keck Interferometer.
The Terrestrial Planet Finder (TPF) is a space-based infrared interferometer that will combine high sensitivity and spatial resolution to detect and characterize planetary systems within 15 pc of our sun.
The paper presents a partial account of control lessons learned during the development of the Micro-Precision Interferometer (MIP) testbed.
Optical and infrared interferometers will open new vistas for astronomy over the next decade.
The Laser-Stabilized Imaging Interferometer (LASII) concept is being developed as a candidate for the next generation of optical resolution beyond Hubble Space Telescope (HST). The essential ingredients are: a rigid and stable structure to minimize mechanical and thermal distortion, active control of the optical geometry by a laser metrology system, a self-deploying structure fitting into a single launch vehicle, and ultraviolet operation. We have modified earlier design concepts to fit the scale of an intermediate sized NASA mission.
The Integrated Modeling of Optical Systems (IMOS) Integration Work Bench at JPL has been used to model the effects of structural perturbations on the optics in the proposed Orbiting Stellar Interferometer (OSI).
A modified Twyman-Green interferometer is in use that makes possible wavefront testing of optical filters at any wavelength from 200 to 1100 nanometers. The use of mirrors for collimation and pupil imaging makes the intrument achromatic, and therefore the focus is fixed over the entire bandwidth.
Deep Space 3 will fly a stellar optical interferometer on three separate spacecraft in heliocentric orbit: one spacecraft for the Michelson beam combining optics, and two spacecraft for each of the starlight apertures.
The New Millennium Interferometer (DS-3) Mission is described along with a new candidate observation plan which takes advantage of an observation mode in which data is collected as the spacecraft are in relative motion.
The Micro Arcsecond Metrology Testbed (MAM) is a laboratory-based, long baseline, white-light interferometer inside a vibration-isolated vacuum tank.
This paper proposes a vibration attenuation strategy for spaceborne optical interferometers to meet their sub-micron positional stability requirements.
NASA Goddard Space Flight Center (GSFC) has been actively developing the laser transmitter for the Laser Interferometer Space Antenna (LISA) program since the late 2017. We have delivered a prototype laser transmitter to the LISA program for performance evaluationin 2021. We continued to further develop the LISA laser with a goal of advancing the technology readiness level (TRL) of the laser to 6 by the end of 2023. In this paper, we report on the progress we made on the laser development for the LISA program.
The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational-wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational-wave observations by LISA to probe the universe.
There is a large inter disciplinary need for high precision angular sensors in state-of-the-art technologies. This particularly applies to optical metrology in the field of Extreme Ultraviolet (EUV) or X-ray where the optics are commonly characterized in terms of slope errors at a nanoradian scale level. Here, in this paper, we present the in-lab development of an angular sensor based on a single reflection compact Sagnac interferometer using instantaneous phase shifting. Our automated prototype and first results show less than 15 nrad RMS repeatability, at least 200 nrad sensitivity and 280 nrad reproducibility over 100 μrad angular range.
Here, we describe a magnetic field sensor based on a spin wave interferometer. Its sensing element consists of a magnetic cross junction with four micro-antennas fabricated at the edges. Two of these antennas are used for spin wave excitation while two other antennas are used for detection of the inductive voltage produced by the interfering spin waves. Two waves propagating in the orthogonal arms of the cross may accumulate significantly different phase shifts depending on the magnitude and direction of the external magnetic field. This phenomenon is utilized for magnetic field sensing. The sensitivity attains its maximum under the destructive interference condition, where a small change in the external magnetic field results in a drastic increase of the inductive voltage, as well as in the change of the output phase. We report experimental data obtained for a micrometer scale Y 3 Fe 2 (FeO 4 ) 3 cross structure. The change of the inductive voltage near the destructive interference point exceeds 40 dB per 1 Oe. The phase of the output signal exhibits a π-phase shift within 1 Oe. The data are collected at room temperature. Taking into account the low thermal noise in ferrite structures, we estimate that the maximum sensitivity of the spin wave magnetometer may exceed attotesla.
X-ray grating interferometry allows for the simultaneous acquisition of attenuation, differential-phase contrast, and dark-field images, resulting from X-ray attenuation, refraction, and small-angle scattering, respectively. The modulated phase grating (MPG) interferometer is a recently developed grating interferometry system capable of generating a directly resolvable interference pattern using a relatively large period grating envelope function that is sampled at a pitch that is small enough that X-ray spatial coherence can be achieved by using a microfocus X-ray source or G0 grating. We present the theory of the MPG interferometry system for a 2-dimensional staggered grating, derived using Fourier optics, and we compare the theoretical predictions with experiments we have performed with a microfocus X-ray system at Pennington Biomedical Research Center, LSU. The theoretical and experimental fringe visibility is evaluated as a function of grating-to-detector distance. Additionally, quantitative experiments are performed with porous carbon and alumina compounds, and the mean normalized dark-field signal is compared with independent porosimetry measurements. Qualitative analysis of attenuation and dark-field images of a dried anchovy are shown.
Precise measurements of the plasma density in ionized gas cells and discharged capillaries are critical to the design and operation of plasma-based accelerators, active plasma lenses, and plasma-based radiation sources. In this manuscript, a spectral-domain common-path second-harmonic interferometer is upgraded with the simultaneous measurement of the group and phase velocity, allowing for high-sensitivity density characterization (from the phase velocity advance) without the need for phase tracking from zero-density (enabled by the group velocity delay). The technique is applied to 1.5-cm-long plasma structures, without density ambiguity in parameter scans with >2π phase jumps. Finally, the single-shot sensitivity in phase retrieval is demonstrated at 63 mrad, equivalent to a density-length product of 1.8·10 15 cm -2 . This is an improvement of ×45 compared to group velocity analysis alone.