White-Light Method: A New Sensor For The Optical Evaluation Of Rough Surfaces

Abstract

In recent decades the importance of surface roughness as a quality characteristic has increased remarkably. Optical methods for asperity measurements have been investigated, in particular because of their principal advantage of permitting in-process or on -line measurements. This paper reports on a new optical method, the so-called white -light method, which determines a surface parameter, the optical contrast C, that represents the quotient of the standard deviation and mean value of the resultant light intensity. The scanned and converted optical information of a strongly defocused image of the rough surface leads to a good correlation between optically and mechanically evaluated surface parameters. This holds true for surfaces that can be measured without severe distortions due to the mechanical scanning procedure. With reference to industrial applications, the measuring range of this system lies in the interesting region of 0.06 AmSRa_ <10 µm. Efforts are currently being made to bring this type of sensor from the laboratory to the prototype stage for practical use.

Computer Analysis of Interferograms by Fitting Quadratic Forms

“…In the evaluation of optical surfaces [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] the need arises to determine the following basic parameters : the shape of the surface, its deviation from a perfect surface of the same shape and the roughness of the optical surface . This can be achieved by three main methods ; stylus, pneumatic gauge and interference methods .…”