Fibre optic sensor for surface roughness measurement
Date
1995
Authors
Bohlmann, Jan
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Abstract
The surface roughness of a manufactured part plays an important role in production processes. In some cases the surface roughness needs to meet exact specifications to ensure proper functioning of the part. The key to minimizing production costs is the correct measurement and description of the surface. Two general types of measuring systems are in common use: contact and non-contact devices. A mechanical profiler, for example, works by mechanical contact of a diamond tip that travels over the surface and measures local height variations. In this thesis a fibre optic interferometer sensor system, originally designed to measure pressure variations, is evaluated as a non-contact surface profile measurement device. Software has been developed to calibrate the system and to acquire surface data, which then is used to pe1iorm surface parameter calculations. In an evaluating comparison both devices, the stylus and the fibre optic interferometer system, measure the same surface samples which represent different machining processes. Limitations of the system are evaluated by measuring the diameter of the laser spot and its standoff distance from the surface.