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合成孔径激光成像雷达系统中可调谐激光器的非线性啁啾,引起回波信号傅里叶频谱的展宽和相位的误差,影响距离向和方位向分辨率。实际测量了激光器的频率非线性,利用光纤法布里-珀罗干涉仪,测量激光器频率随时间的变化,得到高阶非线性项,给出了实验结果。以此为依据,研究了点目标回波外差信号的傅里叶频谱。通过改变分析信号的时间采样窗口宽度,压缩频谱宽度和相位误差,降低了非线性影响。在保证相位精度π/4时,得到了优化的时间采样窗口宽度。
The nonlinear chirp of tunable lasers in synthetic aperture laser imaging radar system causes the widening and phase error of the Fourier spectrum of the echo signal, which affects the range and azimuth resolution. The nonlinear nonlinearity of the laser was measured. By using the fiber Fabry-Perot interferometer, the laser frequency was measured and the higher-order nonlinearity was obtained. The experimental results were given. Based on this, the Fourier spectrum of point-target echo heterodyne signal was studied. By changing the time-sampled window width, compressing the spectral width and the phase error of the signal, the nonlinear effect is reduced. Optimized time-sampling window width is obtained when the phase accuracy is π / 4.