Design And Research Of Micro-Display 3D Topography Measurement System

With the development of technology and people's constant pursuit of science and technology,three dimensional topography measurement is widely used in medical treatment,product testing,safety protection,military reconnaissance,etc..According to the method of measurement,it can be divided into contact measurement and noncontact measurement.The contact measurement technology with high measurement accuracy is more mature,but the measurement speed is slow and can't be used for nondestructive testing.Non-contact measurement is rapid and does not cause damage to the measured object,so it has wide application prospects.In this paper,the object is measured by the projected grating phase method.The height of the object leads to the structural grating distortion,when the structure grating is projected onto the surface of the object measured.The phase information related to the height of object measured can be obtained by image processing of the distorted fringes and the reference fringes.Through the linear relationship between the phase and the height of the object,the 3D topography of the object is reconstructed to achieve the purpose of measurement.Based on the measurement system,the main work of this paper is as follows:Through the analysis of the whole system,FPGA development platform and schematic and PCB were designed.First of all,the Verilog code of LCOS microdisplay is designed based on FPGA development board.The functional simulation test platform was set up and the functional simulation was carried out by analyzing the timing of the driving signal of the LCOS module.The design of the micro-display module drive circuit was realized.Secondly,the Verilog code design of CMOS image acquisition module is completed by calling FPGA internal IP core based on FPGA.The simulation test environment is constructed to realize the function simulation.At last,the normal image acquisition is realized.Based on the crossed optical axis system,the system is built and the system verticality and parallelism are calibrated.The performance of the micro-display 3D topography measurement system is analyzed by the actual measurement.Based on MATLAB,an image processing program is prepared for image preprocessing and noise processing.Then,the FourierTransform Profilometry is used to transform the image from time domain to frequency domain and to extract the fundamental frequency and folded phase.The real phase information is obtained by using the quality map guided phase unwrapping method with integral to solve the folded phase.Finally,according to the linear relationship between phase and height to restore the 3D shape of the object.