Studies On A Optical Three-dimension Phase Profilometry Measurement Technology

Since 1980s, optical three-dimensional(S-D) shape phase measurement was developed sharply, with the development and application of laser technology , CCD image sensor, and computer image processing technology, so far it is more than 20 years . In these years the technology is very popular with many advantages such as: non-contact, full-field measure, high accuracy and sensitivity, automation. But in actual application the following problems which are urgent to solve are:( 1 ) suiting the industrial environment ; ( 2 Realizing phase-shifting with high accuracy; ( 3 ) measuring large-scale object .In order to solve these problems ,the improved and new methods are presented by experiment in this dissertation, which are based on theory of optical 3-D shape phase measurement and MATLAB language .In this dissertation, firstly the development, the application, the hot aspects of research and the future research trends of optical 3-D shape phase measurement are included in details. The principle of measuring method(such as phase measuring profilometry , Fourier transform profilometry), the advantage and disadvantage of them and the source of errors are also analyzed. Secondly, in phase unwrapping to overcome the spread of wrong point, changing the patch of unwrapping phase is done to improve the correctness of it. Then, the relation between the unwrapping phase and the height of reconstructed object is discussed detailedly. The data processing, algorithm analysis and reconstructing object are done for the collecting fringe image which are all based on MATLAB language, In all these achievements, the improvement and innovation aspect are following:a) In order to stabilize the interference fringe, a new equivalent shifting object method is presented by using fringe stabilizing device to stabilize the interference fringe though moving object and CCD camera which fixed on a precise moving platform together, The experimental result shows thefringe drift is less than A /20 in five minutes , and the equivalent phase shifting precision is X /100 . Furthermore the system is very simple, performance reliable and operating convenience, stabilize and better repeatability, it will take an important role in improving the measure precision of 3-D phase profllometry.b) A method for large-scale object measurement is presented without phase shifter in this paper. The sinusoidal gray fringes are simulated by computer and projected on the object by the liquid-crystal light valve in this method, in with the phase-shifting is controlled by computer. Then the deformed fringes modulated by object is collected by CCD camera, so optical 3-D phase measurement for large-scale object can be realized. The result shows this measure system is very simple, performance reliable, operating convenience , and its precision approaches to 1% .it takes an important role in large-scale measurement and in practice the new method shows stronger practicality and popularly application prospect.