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Enhancement of Defect Visibility in Optical Birefringent Images

IP.com Disclosure Number: IPCOM000087824D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Stobbs, WM: AUTHOR

Abstract

In the preceding article, Matthews and Plaskett had proposed the super-imposition of an appropriate long range stress on the stress-field of a dislocation in order to increase the dislocation visibility. Application of the stress will give a different background intensity so that the defect image will be more clearly apparent.

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Enhancement of Defect Visibility in Optical Birefringent Images

In the preceding article, Matthews and Plaskett had proposed the super- imposition of an appropriate long range stress on the stress-field of a dislocation in order to increase the dislocation visibility. Application of the stress will give a different background intensity so that the defect image will be more clearly apparent.

It is proposed that the optimum stress field to be applied for observation of defects is simply one-half the value for reversal in background from dark to light. This can be used as a way of quantifying the contrast changes of the defect as a function of applied stress in order to give an accurate determination of the magnitude of the Burgers vector of the defect, using a null comparison method.

If a crystal would be liable to be damaged if a long range stress field were superimposed, an improvement in contrast can still be obtained by using a quarter-wave plate in conjunction with the analyzer and polarizer. The quarter- wave plate is used to get the background grey for optimum contrast and minimum exposure of the dislocation image. A quarter-wave plate can also be used to quantify the strain field of the dislocation by noting how the contrast changed as a function of background and transmitted intensity.

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