| Frequency modulated continuous wave(FMCW)laser interferometry is a high-precision coherent detection technology.It has non-contact and large dynamic range measurement capabilities.It can realize displacement,temperature,pressure,and strain through the conversion of optical path difference and physical quantity.The measurement of isophysical quantities has been broadly used in military equipment and modern lithography machine manufacturing fields of study.Aiming at the problems of low resolution of interference signals,low sampling rate,and slow signal processing speed in the current optical fiber displacement measurement technology,this paper develops a frequency-modulated continuous kymo lottomr interferometric displacement measurement signal handling system based on a high-speed ARM chip.Non-contact,high-resolution nano-displacement measurement.Based on the detailed theoretical research of FMCW laser interferometry technology,this thesis develops a frequency modulated continuous wave laser interferometer based on Fabry-Perot interference structure.First,DFB semiconductor laser is used as the system light source to build the measurement optical path,and the laser is modulated by sawtooth wave to generate the interference beat signal;then the STM32H743 chip with the main frequency of 400MHz and the maximum ADC conversion rate of 4.5MSPS is selected as the core processor to control the beat frequency.The signal is collected and processed at high speed,and based upon this central processing unit,the software platform exploitation and hardware Integrated circuit devise of the frequency modulated continuous wave laser interference signal handing system are implemented;finally according to the characteristics of the beat signal formed by optical FMCW interference,the beat signal demodulation is designed and written The algorithm uses the linear relationship between the difference of light and the phase gression to demodulate the displacement,realizes the non-contact nano-displacement measurement,and visualizes the display through the Qt platform,completing the design and construction of the FMCW signal processing system.In order to verify the feasibility of the developed frequency modulated continuous wave laser interferometry system,a related optical experiment platform was built,the capability of the semiconductor laser was verified experimentally,and the theory prototype was produced,and the optical path difference OPD related to the optical path difference was obtained.The interference beat signal is finally demodulated to obtain the displacement value via joint commissioning with photoelectric transformation,data collection and application signal handling modules.The experimental consequence indicate that the laser interferometer can achieve a resolution of lnm and a modulation frequency of 32KHz.In the stability measurement experiment of 200?400mm,the standard deviation of the measurement results is less than 3.3nm,and the linear fitting coefficient is within the range of 0?600mm.Above 0.99998,the overall measurement system has the advantages of simple structure,fast response,good linearity,and high stability,and has great application potential in the field of displacement measurement. |
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