Monitoring of the outer diameter of long items using the optical diffraction method

A diffraction method is proposed to increase the resolution (up to several micrometers) of optical measuring transducers that are used in devices for technological monitoring of long cylindrical items (e.g., cables, wires, cords, etc.). A transformation function that makes it possible to calculate diameters of cylinders regardless of their positions in the region of monitoring is based on the diffraction method for the measurement of the shadow boundaries in optical two-coordinate transducers with a divergent laser beam. The results can be employed for the development of high-accuracy noncontact optical devices for technological monitoring of the outer diameter in cable, tube, and other industries.