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Proceedings Paper

Mapping crystal defects with a digital scanning ultramicroscope
Author(s): John M. Springer Jr.; Enrique Silberman; Roger L. Kroes; Don Reiss
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Paper Abstract

A computer controlled scanning ultramicroscope has been built to assist in the characterization of transparent crystals. The device measures the scattering of a focused He-Ne laser beam by crystalline defects. As an XYZ translation table moves the crystal under the ultramicroscope, the scattered light is measured by a photodetector whose output is digitized and recorded. From this data, contour maps or 3-D perspective plots of the scattering regions of the crystal can be generated to assist in finding patterns of defects which might be correlated with perturbations in the growth process. The verified resolution of the present instrument is about 1 micrometers , which is limited by the minimum step of the stepper-motor driven translation stages, optical diffraction effects, and the sensitivity of the detector at the laser light frequency. The instrument was used to build a database of defects patterns in commercial laboratory grown triglycine sulphate (TGS) crystals, and to map defects in a TGS crystal grown from aqueous solution during the flight of Spacelab 3. This crystal shows indications of a reduction both in the generation of defects at the seed-new growth interface and in their propagation into the new crystal.

Paper Details

Date Published: 1 December 1991
PDF: 5 pages
Proc. SPIE 1557, Crystal Growth in Space and Related Optical Diagnostics, (1 December 1991); doi: 10.1117/12.49597
Show Author Affiliations
John M. Springer Jr., Fisk Univ. (United States)
Enrique Silberman, Fisk Univ. (United States)
Roger L. Kroes, NASA/Marshall Space Flight Ctr. (United States)
Don Reiss, NASA/Marshall Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 1557:
Crystal Growth in Space and Related Optical Diagnostics
James D. Trolinger; Ravindra B. Lal, Editor(s)

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