Research On Key Technologies In Laser Interference Displacement And Velocity Measurement

With the rapid development of modern science and technology, precision measurement technology becomes an important symbol of national high technology development.Precision measurement is regarded as the key technology in the developed countries. The laser interferometer sensors have a lot of advantages such as simple structure, high precision and non-contact measurement, indicating a good application prospect in the measurement of physical quantity such as velocity. In this paper, by combing the modern signal processing methods and laser sensor technology, the precision measurement theories and key technologies are studied.The birefringent dual-frequency He-Ne laser has the advantages of compact structure,low cost and the stable laser frequency-difference. In this paper, we report a new signal-processing scheme based on a DSP lock-in amplifier and a low-frequency (millihertz)measurement algorithm. Theoretical analysis and simulation results are presented. The velocity measurement experiments by using a high-precision linear stage (PI) are performed to verify the performance of the laser Doppler velocimeter (LDV). Compared with the previous dual-frequency LDV,the average velocity resolution of the developed LDV is improved from 0.31 mm/s to 0.028 mm/s for a target without the rotational velocity. The system has strong anti-disturbance ability, compact structure, indicating great promise in non-invasive measurement.A practical homodyne laser interferometer which used cubic corner reflector instead of plane mirror for measuring large-scale displacement is developed in view of the difficulties in adjusting the light path. The displacement measurement theory and the signal processing method are proposed. Experimentally, PI's high-precision commercial electric displacement platform is included in the displacement measurement to evaluate the performance of the interferometer during the experiment. Experimental results show that the improved interferometer's displacement measurement precision can reach less than 0.7?m in the hundred mm large-scale displacement measuring process. The error source in the measuring process is analyzed, and the results obtained are conformed to that of the experiments. The designed homodyne laser interferometer with compact structure, low cost and high repeatability has reached a practical level.In addition, a laser mouse self-mixing interferometer with compact structure and low cost is fabricated in the paper for measuring large-scale displacement. Based on the principle of the self-mixing interference effect, a cost-effective laser mouse is chosen as the light source for displacement measurement. The measurement data is eventually transferred to the Linux operating system by the Bluetooth. The measurement theory and the Bluetooth technology are proposed. Experimental results show that the developed system can implement the displacement waveform recovery well. The system has compact structure,strong anti-disturbance ability and cost-effectiveness, indicating great promise in non-invasive measurement.