Kofsky I L, Geller J D, Miller C S
Appl Opt. 1972 Oct 1;11(10):2340-6. doi: 10.1364/AO.11.002340.
Diffraction arid partial coherence cause errors in the measurement of small-scale photographic detail by microdensitometers and projection systems. The optical imaging nonlinearities can be avoided by scanning the silver distribution with a narrow beam of energetic electrons and counting the secondary quanta that are excited. It is found that the number of low energy (secondary) and high energy (backscattered) electrons emitted from various emulsion types as well as the characteristic Ag x-ray fluorescence are measures of the local silver concentration. A mechanism for the secondary electron contrast, which is only in part due to surface relief, is proposed. Spatial frequencies up to 2280 1p/mm have been retrieved by such scanning electron beam probes.
衍射和部分相干性会在使用微密度计和投影系统测量小尺度照片细节时导致误差。通过用一束窄的高能电子束扫描银分布并对激发的二次量子进行计数，可以避免光学成像非线性。研究发现，从各种乳剂类型发射的低能（二次）和高能（背散射）电子的数量以及特征性银X射线荧光是局部银浓度的度量。本文提出了一种二次电子对比度的机制，其部分原因仅在于表面起伏。通过这种扫描电子束探头已经获取了高达2280线对/毫米的空间频率。
