A virtual instrument based on lightwave scattering by surfaces for real-time mapping of atmospheric corrosion of metals

The present work reports the design and implementation of an optical-sensor based virtual instrument for visualizing and estimating the degree of corrosion of metal surfaces exposed to atmosphere. A platform carrying the specimen plates was driven by a stepper motor assembly horizontally in XY directions. An opto-electronic transmitter-receiver unit was fixed vertically very close to the platform so that the sample surfaces may be scanned by a light beam. The reflected and scattered optical signals from each point in the scanned area were acquired by the sensor module. A parameter incorporating the relative values of these signals proved to be a fairly reliable measure of the surface texture, which in turn consistently represented the degree of corrosion. These signals interfaced with a personal computer enabled 3D visualization of the magnitude of the corrosion level of the surface and 2D mapping of the surface corrosion.