Approach Of Measuring 3-D Profile With Binary Optical Element

The measurement of the 3-D contour is increasingly important in high speed examination on pipelining, quality assurance, robot visual, shape analog, automatic processing, reverse engineering and diagnosis. Noncontact optical measurement method is commonly considered to be the most promising way for 3-D contour measurement because of its high resolution, nondestruction and high speed in data gathering. Presently there are many methods for 3-D measurement, among which triangle method is generally adopted for its simple system structure, high speed in measurement and capability for real time processing.The application of the BOE in the 3-D measurement has been investigated in this paper. A 3-D measurement system is designed and established based on the triangle method,in which BOE working as the producer of the structural light. Three tasks are fulfilled in this paper, firstly, the diffraction characteristics of the BOE are deduced; secondly the system calibration, data gathering and processing are introduced in detail. Finally all matters which have influence on the precision of measurement are analyzed.Based the diffraction theory of optical wave, designed by computer and etched to 2 or more steps of surface relief structure by laser beam (or ion beam/electron beam) on the substrate (or the surface of the traditional optical device), BOE is a kind of purely phase modulation diffraction device with extremely high diffraction efficiency. The BOE designed and made in this paper is capable of converting the incidental laser beam into structural light of 2 dimensional dots array, and the diffraction image is nonlocality. After calibration, the distribution of the dot array can be calculated according the etching parameters and distance of diffraction. The dots array modulated by the surface of the object to be measured can be taken by a camera and measurement parameters are recorded, then the 3-D contour of the object measured can be obtained by processing the data gathered.The dot array producer which is made up of BOE and diode laser is small in size, light...