Research For Interference Data Processing Technology Of Photo-elastic Modulation Based On DSP

As a kind of spectral detection technology with high modulation frequency,wide spectral range and good anti-vibration performance,the photo-elastic modulation Fourier transform spectrometer(PEM-FTS)has a broad development foreground and application value in the field of transient spectrum detection such as aerospace,environmental protection,industrial production and life sciences.The core device of the PEM-FTS is photo-elastic modulator,because it's modulation frequency is high,can produce tens of thousands of interferograms per second,so the system needs for a higher speed data processing methods to achieve interference signal spectral recovery.Therefore,this paper focuses on the high-speed processing technology of the photo-elastic modulation interference data.In this paper,based on the basic principle of the optical modulation interference,the characteristics of the photo-elastic modulation interference signal are analyzed.According to the photo-elastic modulation interference signal characteristics,several key techniques of data preprocessing are studied emphatically,such as apodization,filtering,phase correction.Because of the problem of complex calculation of Forman and Mertz phase correction method,an improved phase correction method is proposed to reduce the Mertz method calculation.The experimental results show that this method can reduce the computational complexity by half.The nonuniform fast Fourier transform(NUFFT)algorithm based on the convolution interpolation of Gaussian kernel function is studied in this paper.And analyzing the influence of different parameters on the inversion spectrum.The NUFFT algorithm can quickly and accurately realize the spectral recovery of the photo-elastic modulation interference signal under the premise of selecting the parameters reasonably.Based on the FPGA + DSP high speed data processing platform,the apodization,filtering,phase correction and NUFFTalgorithm of 671 nm laser and 500 K blackbody radiation signal are realized on TMS320C6713 DSP chip.Finally,the experiment platform of the PEM-FTS system is built.On the basis of the theoretical verification,the experiment is carried out with compound color light as the radiation source.The experimental results show that the data processing algorithm is feasible.The algorithm reduces the quantity of data,speeds up the data processing speed,and satisfies the requirement of the system's high speed processing.