Peculiarities of optical formation and filtering the images and diffraction patterns of volumetric objects applied to 3D measuring technologies

Abstract

Constructive method for the formation and filtering Fraunhofer diffraction patterns and images of volumetric objects has been developed applied to 3-D measuring technologies for noncontact dimensional inspection. This method is simple, physically obvious and at the same time, sufficiently strict for engineering applications. It is based on the model of equivalent diaphragms, according to which the problem of light diffraction on volumetric bodies is reduced to the analysis of diffraction phenomena on the plane diaphragms using the Kirchhoff-Fresnel approximation. Dependencies between the characteristic parameters of the diffraction patterns and geometric dimensions of 3-D typical objects were found. Suggested efficient algorithms allow by corresponding processing of diffraction patterns to determine transverse and longitudinal sizes of extended objects with the errors 0.1 percent and 1 percent, respectively. Peculiarities of coherent optical processing the 3-D objects are investigated by the example of high- frequency filtering (contouring) of volumetric edges with perfectly absorbing and reflecting inner surfaces. Results of the investigations showed a satisfactory agreement of the theoretical and experimental data.