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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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Light scattering off particles flowing through a two-slit interference pattern can be used to measure the shear stress of the fluid. We have designed and fabricated a miniature diffractive optic sensor based on this principle.
The current NASA WFIRST (Wide-Field InfraRed Survey Telescope) coronagraph instrument (CGI) design allocates two subband filters per each full science band in order to contain system complexity and cost. We present our detailed investigation results on the adequacy of such a limited number of finite subband filters in achieving broadband dark hole contrast with a shaped pupil coronagraph (SPC). The study is based on diffraction propagation modeling with realistic WFIRST optics, where each subband’s image plane electric field is estimated from pairwise pupil plane deformable mirror (DM) probing and image plane intensity averaging of the resulting fields of multiple (subband) wavelengths. Multiple subband choices and probing and control strategies are explored, including standard subband probing; mixed wavelength and/or weighted Jacobian matrix; subband probing with intensity subtraction; and extended subband probing with intensity subtraction. Overall, the investigation shows that the achievable contrast with a limited number of finite subbands is about 2~2.5x worse than the designed contrast for the current SPC. The result suggests that future shaped pupil designs should be optimized for slightly broader bandwidths than the intended science bandpasses if limited subbands are used for wavefront sensing via probing.
An analytical description of the scattered light from a 10 meter diameter Diffractive Optical Element lens-based telescope operating at 1 micron wavelength has been formulated.
The overall scope of this NESC study was to identify (or develop) a tool, methodology, or process that can inspect a ceramic capacitor and consistently return repeatable grain size distribution results. It is important to note that the development of a machine learning technique was considered as an option for this study, but only if an existing automated tool was not available. This report explains why the Electron Backscatter Diffraction analysis method for grain structure and size distribution was deemed a suitable candidate for this work.
Diffraction of hf radio waves by ionospheric irregularities - radiation from artificial satellites
Oxygen adsorption on tungsten crystal face studied by back-reflection low energy electron diffraction
Electromagnetic wave propagation and diffraction in plasmas
Annular aperture diffracted energy distribution for extended source
Low energy electron diffraction study of oxygen adsorption on molybdenum /111/ surface
Diffraction of inelastically scattered electrons in tungsten at low energies
Plane wave scattered and diffracted fields for infinite cylinder of arbitrary cross section solved by boundary perturbation method and conformal mapping
Epitaxial growth of indium antimonide thin films as studied in situ by electron diffraction
Diffraction patterns calculated by computing two dimensional Fourier transform of aperture electric field
X rays and gamma rays interaction with crystals analyzed by quantum electrodynamics Green function methods, emphasizing Mossbauer gamma ray diffraction optics
X ray diffraction studies of kamacite /alpha-iron/ from iron meteorites indicating shock induced alteration and unstable polymorph influence
X ray and neutron diffraction studies of NaCl type beta phases of silver-bismuth selenide/sulfide, determining crystal structure
Crystal-diffraction spectrometer, combined with a lithium-drifted Ge-diode detector, performs high-resolution gamma ray spectroscopy on the complicated neutron-capture gamma ray spectra. The system is most useful in the 1-3 MeV energy range and improves the signal to background ratio.