Research On 3D Measurement Technology Of Micro-structure Based On Bi-telecentric System

With the increasing demand for precision products in modern society,the precision requirements of industrial components are getting higher and higher.Checking measur ements technology on precision component is very important and relatively lagging be hind.For current situation,the main measurement method is the probe contact measur ement.While in this way,positioning is complicated and efficiency poor,probes even scratch the surface of work piece.Therefore,it is of great practical value to study an efficient,accurate and automatic measurement method.In this paper,bi-telecentric im aging system and laser parallel scanning technology are adopted to realize a three-dim ensional accurate measurement on micro three-dimensional structure of industrial comp onents.The main work can be divided into following 3 parts:Firstly,Current study situation and main technique of three-dimensional measureme nt has been analyzed.Thereupon a three-dimensional accurate measurement method bas ed on bi-telecentric optical system has been proposed.Combined mathematical model of bi-telecentric lens with parameter characteristics of three-dimensional measurement s ystem,singles camera measurement model has been established.On this basis,double cameras model with special double axis vertical structure has been proposed.Theoretic ally speaking,it is more outstanding in measure accuracy,efficiency and reliability.Secondly,an experimental measurement platform based on an industrial camera with bi-telecentric lens and linear laser source with 635 nm wave length has been established.And the calibration technique of telecentric cameras has been studied.From the three-dimensional measurement on the chamfering structure of a small component,the result shows that the measure accuracy of side length can reach within 0.02 mm and angel accuracy measure can reach within 2'.Combined the distortion model of bi-telecentric lens and modified system model,the compensation system can increase length measure accuracy within 0.01 mm ad angel measure accuracy within 1'.The need for precise measurement of micro structure of precision components is meet.Thirdly,image specifications of LAI(Laser Active Imaging)has been studied,imag e processing technique in this system has been researched and the measurement system software has been designed.To get more accurate measurement,the paper proposes to extract centre line of light stripe based on edge detection of Gaussiam fitting met hod.It is called sub-pixel location algorithm.Compared with Hessian matrix method,i ts processing speed has been increased by two third and it has better robustness on p hase step breakpoint.This research result can realize a rapid and efficient non-contact method for micro structure of precision components measurement.It has great potential advantage in continuous measurement and automatic measurement.