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CO2 Laser Induced Damage to Germanium: Relation to Surface Preparation
Gibson, DR
Barr and Stroud Ltd., Applied Physics Group, Glasgow

MacDonald, CM
Barr and Stroud Ltd., Applied Physics Group, Glasgow

Wilson, AD
Barr and Stroud Ltd., Applied Physics Group, Glasgow


Pages: 12    Published: Jan 1988


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Source: STP1015-EB


Abstract

The laser damage behaviour of germanium is examined in relation to surface preparation methods including alumina polishing, “Syton” polishing, diamond machining and plasma etching. Data on laser damage threshold (LDT), damage morphology, surface absorption, surface roughness and the transmittance of the laser pulse (TLP) are used in conjunction with a thermal model in an attempt to identify the various mechanisms responsible for surface damage in Ge. Alumina and “Syton” polishing result in significantly different LDTs, morphologies and TLPs which can be directly correlated with the predictions of a thermal model based on laser heating of embedded polishing particles. Plasma etching removes polishing debris and thus increases the LDT. Diamond machining gives a wide range of LDTs related to variations in surface topography and work damage. A practical ranking of the effect of surface preparation method on LDT is presented.


Keywords:
CO2 Laser Damage, Diamond Machining, Germanium, Plasma Etching, Polishing

Paper ID: STP18745S
Committee/Subcommittee: F01.02
DOI: 10.1520/STP18745S
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