Signal and noise in modulation transfer function determinations using the slit, wire, and edge techniques.
Signal and noise in modulation transfer function determinations using the slit, wire, and edge techniques.
复制标题
使用狭缝、导线和边缘技术确定调制传递函数中的信号和噪声。
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
B. Reid
中科院分区：
文献类型：
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作者：
I. Cunningham;B. Reid
理想化成像系统的调制传递函数（MTF）可以通过系统线扩展函数（LSF）的傅里叶变换来确定。通过实验确定 LSF 的三种技术需要对狭缝、线或边缘进行成像。本文对这三种技术进行了理论上的建模，以确定计算出的 MTF 中的噪声，作为由量子涨落和随机探测器噪声产生的空间频率的函数。使用 MTF 中的信噪比 (SNR) 来比较这些技术，MTF 定义为 MTF 值与独立测量得出的 MTF 确定集合中的标准偏差之比。结果表明，对于指定的光子注量，边缘法 MTF 在低空间频率下具有最高的信噪比，而狭缝法在高频下更优越。线法信噪比始终不如狭缝法。这表明边缘法更适合测量低频压降等参数，而狭缝法更适合确定高频响应。对于量子噪声受限系统，狭缝法和边缘法相等的交叉频率 (f(e)) 是狭缝宽度和 LSF 测量长度的函数。对于探测器噪声受限的系统，f(e) 仅取决于狭缝宽度。因此，除量子噪声限制狭缝方法之外的所有方法中的 SNR 都可以通过减少测量 LSF 的长度、平滑 LSF 的尾部或通过将尾部拟合到解析表达式来增加。
The modulation transfer function (MTF) of an idealized imaging system can be determined from the Fourier transform of the system's line-spread function (LSF). Three techniques of experimentally determining the LSF require imaging either a slit, wire, or edge. In this paper, these three techniques are modeled theoretically to determine the noise in the calculated MTFs as a function of spatial frequency resulting from both quantum fluctuations and stochastic detector noise. The techniques are compared using the signal-to-noise ratio (SNR) in the MTF, defined as the ratio of the MTF value to the standard deviation in an ensemble of MTF determinations from independent measurements. It is shown that for a specified photon fluence, the edge method MTF has the highest SNR at low spatial frequencies, while that of the slit method is superior at high frequencies. The wire method SNR is always inferior to that of the slit technique. This suggests that the edge method is preferable for measuring parameters such as the low-frequency drop, and the slit method is preferable for determining high-frequency response. The cross-over frequency at which the slit and edge methods are equal (f(e)) for quantum-noise limited systems is a function of the slit width and the length over which the LSF is measured. For detector-noise limited systems, f(e) is dependent on the slit width only. The SNR in all but the quantum-noise limited slit method can therefore be increased by decreasing the length over which the LSF is measured, smoothing the tails of the LSF, or by fitting the tails to an analytic expression.