The black-white stereo technique was applied to the study of small point-defect clusters that were produced by Kr+ bombardment at room temperature. It was found that most of the defects in the first 10nm of the foil depth were vacancies; as were some of the deeper clusters. There was no clear evidence for the presence of interstitial clusters. The defects sometimes exhibited an inconsistent contrast in going from one imaging condition to another. The near-impossibility of establishing that interstitial clusters were not present was demonstrated by the fact that some 53% of the total number of clusters could not be analyzed because they did not exhibit clear black-white contrast under a minimum number of imaging conditions.

H.Fukushima, M.L.Jenkins, M.A.Kirk: Philosophical Magazine A, 1997, 75[6], 1583-602