Research On Laser Frequency Modulation Technique In Absolute Distance Measurement

Absolute distance measurement is an important driving force for the development of the accurate engineering measurement.FM interferometer laser ranging has the characteristics of high precision and absolute measuring of interferometric measurements,which has the important research value and application prospects.This topic focuses on the implementation of laser linear frequency modulation techniques and absolute distance measurement,which for the achievement of the interferometric absolute measuring.The principle of laser linear frequency modulation interferometry for absolute distance measurement was analyzed and studied.For the key requirement of the measurement system—FM linearity,the simulation analysis and hardware system design of the laser linear frequency modulation system was performed,and an FM interferometric absolute distance measurement system was established.Based on the experimental and simulation analysis of the influencing factors of frequency modulation characteristics,the method of non-linear compensation using the standard interferometer and the shaping of the laser spot to improve the range of the system's range,and then to achieve a large size,high precision absolute distance measurement provides research methods and ideas.The specific research content of this paper is as follows:First,on the basis of detailed analysis of the principle of laser linear FM interference absolute distance measurement,a low-power visible light semiconductor laser with a center wavelength of 650 nm is used as a frequency-modulated light source to study its frequency modulation characteristics,including current-frequency,temperature-wavelength,etc.The effect of the current on the laser power and frequency and the influence of the change of the ambient temperature on the wavelength were revealed,and the effective data was obtained,providing the parameter selection for the realization of the linear frequency modulation.Secondly,according to the distance measurement application,an FM ranging system was set up.The MATLAB simulation experiment and distance measurement experiment were carried out.The experimental results were analyzed.The improvement measures were proposed for the non-ideality of the experimental results,and improved MATLAB simulation and experimental research.Finally,another semiconductor laser with LSR980NL-500 high-power non-visible light is used for FM ranging to improve the system's measurement range and ranging accuracy,verify the feasibility of the design scheme and the effectiveness of the improvement measures.Distance measurement provides program selection and technical support.A system model for FM interferometric ranging using a DFB laser as the FM light source was established.The maximum range of the beat frequency under low frequency power visible semiconductor laser frequency modulation was 140mm,and the range of the distance between the front and rear beat frequency was increased by 41%.In the case of a high-power invisible laser as a frequency-modulated light source,collimation and constant temperature processing improve the system's ranging range and range accuracy.This paper studies the frequency modulation technology of FM laser in absolute distance measurement,and provides research methods and ideas for large-scale and high-precision measurement.It has very important application value.