Hessel K R
Appl Opt. 1974 May 1;13(5):1023-8. doi: 10.1364/AO.13.001023.
Following conversion of a time signal to intensity transmittance variations on film, a lens can be used in collimated coherent light to project a light intensity pattern that is an estimate of the power spectrum of the data contained on the film. To record a general biplanar signal on a film a transmittance bias level is required. The effect of this bias is defined as noise, and signal-to-noise ratios are computed for single frequency signals. Both the unapodized aperture and a cosine-shaped apodization function are considered. The effect of the size of the aperture used to record the signal on film is shown, as is the effect of the recording film speed variations. Film thickness variations reduce the performance of the analyzer; this effect is also computed.
在将时间信号转换为胶片上的强度透射率变化之后，可以使用透镜在准直相干光中投射出一个光强图案，该图案是胶片上所包含数据功率谱的估计值。为了在胶片上记录一般的双平面信号，需要一个透射率偏置电平。这种偏置的影响被定义为噪声，并针对单频信号计算信噪比。同时考虑了未加窗孔径和余弦形加窗函数。展示了用于在胶片上记录信号的孔径大小的影响，以及记录胶片速度变化的影响。胶片厚度变化会降低分析仪的性能；这种影响也会被计算出来。
