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Optical Method to Determine Magnetic Coating Thickness

IP.com Disclosure Number: IPCOM000046514D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Mastrangelo, CJ: AUTHOR

Abstract

Thickness measurements of magnetic coatings have traditionally been made using X-ray analysis. This is a well-understood and accurate method, but requires a minute or so of counting to provide sufficient data for a thickness determination. In addition, there is a current concern of the environmental hazard of X-rays. Because of the time required with X-ray analysis, it is not feasible to monitor thickness in real time, that is, while the thickness is being reduced due to buffing. If an instantaneous detection method were available, it would allow monitoring magnetic coating thickness change while it was happening.

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Optical Method to Determine Magnetic Coating Thickness

Thickness measurements of magnetic coatings have traditionally been made using X-ray analysis. This is a well-understood and accurate method, but requires a minute or so of counting to provide sufficient data for a thickness determination. In addition, there is a current concern of the environmental hazard of X-rays. Because of the time required with X-ray analysis, it is not feasible to monitor thickness in real time, that is, while the thickness is being reduced due to buffing. If an instantaneous detection method were available, it would allow monitoring magnetic coating thickness change while it was happening.

The present method uses simple absorption of visible light (blue) and the degree of the absorbancy due to the thickness of the magnetic coating. Using a current magnetic disk and blue light, it is possible to monitor the inside diameter (ID) and outside diameter (OD) thickness change with a monochromator to isolate the reflected wavelength most sensitive to the coating thickness.

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