Characterization of 'Optical Grade' Germanium
FRANKFORD ARSENAL PHILADELPHIA PA
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Various techniques were used to characterize optical grade germanium as to its suitability for optical element fabrication. Major concern centered about various material defects causing gradients in the refractive index and the need to detect these defects in germanium prior to its processing into optical elements. Cursory tests employing such methods as IR transmittance, x-ray radiography, x-ray topography and resistivity mapping were made on several germanium blank discs obtained from primary raw material suppliers. The tests indicated that these methods gave somewhat limited results and by themselves provided only a circumscribed characterization of the material. A review of the literature on interferometry suggests that IR laser interferometry might be a promising quality assurance technique, although the extent of sample preparation for this technique may make its use too costly in any proposed quality inspection system.
- Lasers and Masers
- Test Facilities, Equipment and Methods