Study On The Signal Processing Algorithms Of Frequency Modulated Continuous Wave Laser Ranging System And Its Autofocusing System

Large space precision coordinate measuring is the basis of the large equipment manufacturing and precision engineering installation,occupying the important position in the field of energy,defense industry,space science and technology,etc.The real-time and high precision large size measuring become the development direction of large space precision coordinate measuring.The real-time and high precision large size measuring become the development direction of large space precision coordinate measuring.Frequency modulated continuous wave(FMCW)laser ranging has the advantages of high precision,high resolution,large distance measuring range on large absolute distance measurement.More and more researchers paid attention on it.As a non-contact measurement method,FMCW ranging has higher precision and resolution compared with the traditional laser phase method and laser pulse method,So it has a broad application prospect in application of large size and high precision measurement in the range of 10-100 m.Studying FMCW ranging principle and further improving its ranging precision and range resolution have become the current research hotspot in the field of cooperation target laser ranging.In this paper,the main research work is as follows: 1.On the basis of fully grasping the frequency modulation continuous wave laser ranging principle,the signal processing algorithm is researched.The software modules such as optical frequency signal data acquisition,signal error recognition,equispaced-Phase Resampling Nonlinearity Correction Algorithm,signal splicing,all-phase FFT and distance fast calculating algorithm were programmed and integrated using Lab VIEW;2.The effect of nonlinear frequency modulation on the ranging accuracy of FMCW laser ranging system was researched deeply.After grasping the principle of equispaced-Phase Resampling Nonlinearity Correction Algorithm to eliminate nonlinear frequency modulation,improvements was made by proposing hardware-based equispaced-phase resampling nonlinearity correction algorithm.Hardware-based equispaced-phase resampling nonlinearity correction algorithm has higher ranging precision and higher resolution than software-based equispaced-phase resampling nonlinearity correction algorithm.And the method is more simple.It can greatly save system memory space and the data processing time;3.A dual-beam laser autofocusing system is designed in this paper.The autofocusing system is based on a liquid lens with less moving parts and fast response time,which makes the system simple,reliable,compact and fast.A novel scheme “Time-sharing focus,fast conversion” is innovatively proposed.The scheme effectively solves the problem that the guiding laser and the working laser cannot focus at the same target point because of the existence of chromatic aberration.This scheme not only makes both guiding laser and working laser achieve optimal focusing in guiding stage and working stage respectively,but also greatly reduces the system complexity and simplifies the focusing process as well as makes autofocusing time of the working laser reduce to about 10 ms.The dual-beam laser autofocusing system based on liquid lens is fully automatic,compact and efficient.It is fully meet the need of dynamicity and adaptivity and it will play an important role in a number of long-range control applications.