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  • 1
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    OBSERVATION OF MISFIT DISLOCATIONS IN GaAs–Ge HETEROJUNCTIONS (1967)
    American Institute of Physics
    Details
    Publication Date: 1967-05-01
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics
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    PAPER CURRENT
  • 2
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    Relief‐exposure characteristics of radiographs in relief (1978)
    American Institute of Physics
    Details
    Publication Date: 1978-02-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
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    PAPER CURRENT
  • 3
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    Surface roughness studies with DALLAS-detector array for laser light angular scattering (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: An attempt is made to develop a better mathematical description of optical scattering phenomena, in order to construct an optical scattering apparatus for reliable and routine measurements of roughness parameters without resorting to comparator standards. After a brief outline of optical scattering theory, a description is presented of an experimental instrument for measuring surface roughness which incorporates optical scattering principles. The instrument has a He-Ne laser which illuminates the test surface at a variable angle of incidence. Scattered light distribution is detected by an array of 87 fiber-optic sensors positioned in a rotating semicircular yoke. The output from the detector is digitized and analyzed in a laboratory computer. For a comparison with experimental data, theoretical distributions are calculated by substituting the roughness profiles into the operand of and integral equation for electromagnetic scattering developed by Beckmann and Spizzichino (1963). A schematic diagram of the instrument is provided and the general implications of the experimental results are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Research; 89; 3-16
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Surface texture characterization by angular distributions of scattered light (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Work at the National Bureau of Standards to develop an on-line optical measurement device and attendant algorithms for automated optical scattering measurements of machined metal surfaces are described. The surfaces could be milled, ground or lapped, and the system is intended to categorize the resulting surface characteristics. The optical device consists of a He-Ne laser which is shone on a surface. The scattered light is captured by a semicircular array of 87 detector elements rotated over the scanned area. The light signals are processed through a digital voltmeter and then an A/D converter. The signals are then stored for later comparisons with optical scattering data obtained by optical instruments used with stylus instruments for characterizing surface topographies. A theoretical model has been defined which relates light scattering and the characteristics of the surface roughness. Initial experimental results with a sinusoidal surface have indicated that although the system can follow the trend of the roughness, the roughness amplitude is as yet uncertainly defined and the computations require excessive time.
    Keywords: QUALITY ASSURANCE AND RELIABILITY
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Surface finish measurement studies (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The performance of stylus instruments for measuring the topography of National Transonic Facility (NTF) model surfaces both for monitoring during fabrication and as an absolute measurement of topography was evaluated. It was found that the shop-grade instruments can damage the surface of models and that their use for monitoring fabrication procedures can lead to surface finishes that are substantially out of range in critical areas of the leading edges. The development of a prototype light-scattering instrument which would allow for rapid assessment of the surface finish of a model is also discussed.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA. Langley Research Center Cryogenic Wind Tunnel Models; p 205-214
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Three-dimensional stylus profilometry (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The method of three-dimensional stylus profilometry is presented together with a computer-based system for transforming the surface topography of a specimen into an intensity image. Examples are given in which intensity images obtained by stylus profilometry are compared with scanning electron micrographs and two other representations of the stylus data. The comparisons are made for three types of surface irregularities: a discrete feature, a periodic profile surface, and a random profile surface. It is shown that stylus profilometry provides high vertical resolution for low sloped surfaces and thus can be useful in revealing features not easily detectable with other methods.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Wind tunnel model surface gauge for measuring roughness (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The optical inspection of surface roughness research has proceeded along two different lines. First, research into a quantitative understanding of light scattering from metal surfaces and into the appropriate models to describe the surfaces themselves. Second, the development of a practical instrument for the measurement of rms roughness of high performance wind tunnel models with smooth finishes. The research is summarized, with emphasis on the second avenue of research.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-CR-182392 , NAS 1.26:182392 , PB88-109921 , NBSIR-87/3586
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Evaluation of methods for characterizing surface topography of models for high Reynolds number wind-tunnels (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Current work by the National Bureau of Standards at the NASA National Transonic Facility (NTF) to evaluate the performance of stylus instruments for determining the topography of models under investigation is described along with instrumentation for characterization of the surface microtopography. Potential areas of surface effects are reviewed, and the need for finer surfaced models for the NTF high Reynolds number flows is stressed. Current stylus instruments have a radii as large as 25 microns, and three models with surface finishes of 4-6, 8-10, and 12-15 micro-in. rms surface finishes were fabricated for tests with a stylus with a tip radius of 1 micron and a 50 mg force. Work involving three-dimensional stylus profilometry is discussed in terms of stylus displacement being converted to digital signals, and the design of a light scattering instrument capable of measuring the surface finish on curved objects is presented.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AIAA PAPER 82-0603 , In: Aerodynamic Testing Conference; Mar 22, 1982 - Mar 24, 1982; Williamsburg, VA
    Format: text
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    NASA TECHNICAL REPORTS
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