Construction And Research Of Linear Ruler Verification System Based On Laser Interferometer

As the most common multi-value length gauge in life,the line ruler can provide effective length standards for various parts,components and complete products,and plays an important role in the transmission of length values.In order to ensure the accuracy of the line ruler in the process of measuring value transmission,the measurement departments at all levels of the country need to carry out related verification of the line ruler.However,the traditional line ruler verification system has problems such as low automation,inaccurate measurement,and poor stability.For this reason,this paper proposes a line ruler verification platform system based on laser interferometer,which uses laser interferometer as the comparison verification standard,and cooperates with the line measurement technology based on image processing to realize the line rule verification work and improve the line rule verification platform.Measurement accuracy and degree of automation.The following are the main work content and innovations of this article as follows:1.Starting from the line ruler verification technology and the realization method of laser interferometer,analyze the line ruler comparison method and the laser interferometer measurement model,and propose a line ruler verification platform system design scheme based on the laser interferometer.The overall design plan is divided into mobile station position measurement and line pattern position measurement.For the position measurement of the mobile station,a sinusoidal phase modulation interferometer and a laser heterodyne interferometer are proposed.For the line pattern position measurement,image acquisition,gray value extraction,Line pattern position measurement method based on main line pattern recognition and pixel pitch calculation,and combined the position of the mobile station and the line pattern position to output the line pattern ruler comparison verification result.2.On the basis of the design scheme of the linear ruler calibration platform based on the laser interferometer,carry out the research and development of each part of the system.Use Redpitaya125-14 as the development platform of the mobile station position measurement system,combined with FPGA technology to achieve high-speed parallel signal processing,and finally obtain the mobile station displacement information.The PGC-CDM phase demodulation algorithm is proposed for the sinusoidal modulation interferometer measurement system,which effectively avoids the nonlinear error caused by the modulation depth and phase delay to the phase generation carrier technology;for the laser heterodyne interferometer measurement system,the mixing filter is used for phase discrimination.The signal processing method of,achieves high-precision phase detection;after comprehensive comparison of the two measurement systems,the laser heterodyne interferometer solution is selected as the mobile station position measurement system.The MER-1070-10GM/GC camera is used to develop a line pattern position measurement system,and the maximum allowable error of the line pattern position and the uncertainty of camera recognition are calculated.Based on the 3D CAD software Soild Works,each component and the overall simulation modeling of the linear ruler verification table are completed to ensure that there are no assembly problems in the actual construction of the system.Using Lab VIEW and Qt Ceator to design the system software,the functions of data acquisition,light source exposure adjustment,rail motion control,line pattern recognition and position acquisition are realized.3.According to the developed linear ruler calibration platform system,the system is built as a whole,and various parts of the system are verified for accuracy.Stability experiment was carried out for the position measurement system of the mobile station.The system drift was less than 500 nm within 10 hours,and the average drift was 0.03 nm per second after straight line fitting;and compared with the indoor 50 m length standard device of Zhejiang Institute of Metrology and Measurement in 100 mm steps.Repeatability experiment with 1 m,2 m,5 m steps: The step experiment shows that the maximum cumulative deviation within 5m is 3.5 μm,and the measurement accuracy can reach 1ppm;the repeatability experiment shows that the system repeatability accuracy can reach 0.8 ppm.For the line pattern position measurement system,a checkerboard calibration board with an accuracy of 1 μm is used to measure the line pattern accuracy.The comprehensive measurement accuracy can reach 3 μm,which can meet various line pattern verification regulations and calibration specifications;and the 5 m steel has been verified through comprehensive verification experiments.The indication error of the tape measure and its grade evaluation.Comprehensively proved the practicability and accuracy of the linear ruler calibration system based on laser interferometer.