Optical techniques are appropriate to industrial inspection tasks because of their noncontact nature, high response speed, and increasing ruggedness and affordability. This paper relates to the development of two electrooptical systems for the inspection of woven webs and of extruded wires. In both cases, parameters of industrial interest are inferred from the light beam distribution after interaction with the material under analysis. Suitable optical configurations provide a laminar light beam which is line array scanned and Fourier transform processed. The emphasis is on the maximization of the measurement reliability, depth of field, and processing speed according to on-line application requirements.
P. Cielo and G. Vaudreuil, "Optical inspection of industrial materials by unidimensional Fourier transform," Appl. Opt. 27, 4645-4652 (1988)