Radiographic detection of 100 A thickness variations in 1-. mu. m-thick coatings applied to submillimeter-diameter laser fusion targets
We have developed x-ray radiography to measure thickness variations of coatings on laser fusion targets. Our technique is based on measuring the variation in x-ray transmission through the targets. The simplest targets are hollow glass microshells or microballoons 100 to 500 ..mu..m in diameter, that have several layers of metals or plastics, 1 to 100 ..mu..m thick. Our goal is to examine these opaque coatings for thickness variations as small as 1% or 0.1%, depending on the type of defect. Using contact radiography we have obtained the desired sensitivity for concentric and elliptical defects of 1%. This percentage corresponds to thickness variations as small as 100 A in a 1-..mu..m-thick coating. For warts and dimples, the desired sensitivity is a function of the area of the defect, and we are developing a system to detect 0.1% thickness variations that cover an area 10 ..mu..m by 10 ..mu..m. We must use computer analysis of contact radiographs to measure 1% thickness variations in either concentricity or ellipticity. Because this analysis takes so long on our minicomputer, we preselect the radiographs by looking for defects at the 10% level on a video image analysis system.
- Research Organization:
- Los Alamos National Lab., NM (USA). Materials Science and Technology Div.
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5186640
- Report Number(s):
- LA-UR-86-2673; CONF-860856-3; ON: DE86015348
- Resource Relation:
- Conference: Conference on review of progress in quantitative NDE, San Diego, CA, USA, 3 Aug 1986; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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