Study On The Principle Of Laser Interference Fringe Pattern Measurement-Measurement Of Micro Object Shape

Three-dimensional(3D)topography measurement technology has been developed.So far it has made many great achievements,especially in optical 3D measurement,because of its wide measurement range,non-contact,and high precision.Its impact and application have penetrated into industry,manufacturing,quality control,reverse engineering,and cultural relics protection.The current measurement technology is mostly based on structural light to achieve,which can't overcome strong background light.Besides,it is difficult to realize the measurement of micro-object.In this dissertation,the laser interference fringe array topography measurement based on the principle of shear interference has been studied,which realized high precision interference fringe projection and overcame introducing phase difference in an independent two-arm transmission beam.In addition,the feasibility of the Fourier transform profilometry is verified by the design of an appropriate band-pass filter,which realizes the non-contact and high precision static measurement of an object.The main research contents are as follows:1.The projection of interference fringes was realized by using the principle of shear interference.A scheme was proposed to overcome the phase difference in the interference arm.Shear elements suitable for a certain wavelength were designed.At the same time,in order to realize the miniature of the optical path,an optical element with 45 degree vertical incidence was introduced.A shape measurement system based on laser interference fringe array was built.2.The design of the phase shift controller based on current parameters was proposed,and the three-terminal input of the laser was realized by using a transistor amplifier.The feasibility of analyzing the phase shift of the laser interference fringe array was verified by using the D/A converter card to quantify the output current.The principle of phase controller based on micro displacement was analyzed and verified.3.The phase unwrapped algorithm was studied and analyzed,The principle of phase unwrapping based on the minimum norm method was deduced,and the correction of phase period was realized.The image filtering was applied to the filtering of the phase noises,and the error of the wrapped phase was improved.4.The laser interferometric array and the algorithms of segmentation and stiching of wrapped phase by using the variable step phase measuring profilometry were studied.The spectrum fringe array,contrasted bandpass effects on fringe processing parameter filter,and Fourier Transform profilometry were analysed.