Apparatus for measuring the thickness of thin layers

US4293767A · kind A · utility

Inventors

• Helmut Fischer · Calw, DE
• Albert Ott · Niedernhausen, DE
• Willi Steegmuller · Nagold, DE

Key dates

• Filing date: Aug 24, 1979
• Grant date: Oct 6, 1981
• Expiry date: Aug 24, 1999

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N23/203
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The apparatus measures the thickness of thin layers on strips and wires which are moved relative to the apparatus. The apparatus is stationary and includes one or more beta emitters directed towards the layer and spatially arranges relative to the longitudinal axis of a beta radiation detector or counting tube which is arranged to the rear of the beta emitter for counting the backscattered beta radiation, and a guide for the strip or wire at a specified distance from the beta emitter. The ratio of the characteristic cross-sectional dimension (D) of the window of the beta radiation detector to the intersecting surface diameter (d) of the intersecting surface layer/intensity distribution curve of the beta emitter, being expressed as D/d=15 . . . 2; with the distance between the layer and the beta radiation emitter being in the plateau region of the curve of the counting rate/distance characteristic obtained by the above feature.