Kniffen S K, Becker M F, Powers E J
Appl Opt. 1992 Mar 10;31(8):1015-29. doi: 10.1364/AO.31.001015.
A hybrid optical-digital processor has been developed that computes both the magnitude and phase of the bispectrum for wide bandwidth (10 MHz to 1 GHz) rf signals. The overall optical architecture is that of a modified Mach-Zehnder interferometer that contains three acousto-optic modulators and appropriate transforming lenses. The intensity distribution in the output plane of the interferometer contains an interference term that represents the real part of the bispectrum multiplied by a spatial carrier (the interference fringes). To isolate the bispectrum information, the output image is digitized and digitally filtered. The imaginary part of the bispectrum is obtained by Hilbert transforming the real part, and then computing the bispectrum magnitude and phase. The processor is tested with four different combinations of rf test signals. Each signal has a bandwidth of either 6 or 12 MHz. Test results that illustrate the performance of the processor in the recovery of magnitude and phase information for the bispectrum of quadratically related signals are presented.
已经开发出一种混合光学 - 数字处理器，它可以计算宽带宽（10 MHz至1 GHz）射频信号的双谱幅度和相位。整体光学架构是一种经过改进的马赫 - 曾德尔干涉仪，其中包含三个声光调制器和适当的变换透镜。干涉仪输出平面中的强度分布包含一个干涉项，它表示双谱的实部乘以一个空间载波（干涉条纹）。为了分离双谱信息，对输出图像进行数字化和数字滤波。双谱的虚部通过对实部进行希尔伯特变换，然后计算双谱幅度和相位来获得。该处理器用四种不同组合的射频测试信号进行测试。每个信号的带宽为6 MHz或12 MHz。给出了测试结果，这些结果说明了该处理器在恢复二次相关信号双谱的幅度和相位信息方面的性能。
