声光频谱仪频率分辨率判断方法研究

频率分辨率是声光频谱仪的一个重要指标。声 光布拉格器件实际衍射光宽度远大于 理论宽度,因 此对声光频谱仪频率分辨率的估计需根据实际衍射光的宽度来判断。本文在现有光学测试平 台下,对单频信号 产生的衍射光,通过高斯函数建立数学模型,利用二分迭代法得到两高斯函数在满足瑞利 判据条件下可 分辨的最小间距。根据光路系统衍射光偏转距离与对应频率带宽,估计系统频率分辨率与 实测系统频率分辨率基本一致。研究结果表明,本文方法能有效估计声光频谱仪的频率分辨 率。

Study on frequency resolution judgment for acousto-optic spectrum analyzer

Frequency resolution is a main parameter of the acousto-optic spectru m analyzer.Because the actual diffraction width of the acousto-optic Bragg device is much larger t han the theoretical width, we need to estimate the frequency resolution of the acousto-optic spectrum anal yzer by the actual diffraction width.Under the existing optical experimental platform,we establis h the mathematical model by the Gaussian function for the diffraction,which is stimulated by one radio frequency (RF) signal.We have solved the two Gaussian function superposition equations by dichotomy,and get th e minimum distance which could be distinguished under the Rayleigh criterion condition.According t o diffraction deflection distance of the optical system and the corresponding frequency bandwidth,we get the estimated frequency resolution.According to the multiplication property of Fourier transf orm,we generated the dual-frequency immediate frequency (IF) signal by the signal generator,and meas ure the frequency resolution of this optical system.The test results show that the estimated frequency resolution and the re al frequency resolution of this optic system are basically the same.We can estimate the acousto-optic f requency resolution by this method.