Abstract The full field X-ray fluorescence (FF-XRF) imaging is a technique capable of analysing the spatial distribution of elements in a sample. An alternative technique is the scanning macro-XRF method. Both techniques are powerful tools for non-destructive analysis of artworks mainly historical paintings. Technically, FF-XRF imaging is usually realised by coupling of a pinhole camera and a position sensitive and energy dispersive X-ray detector. The main advantages of the pinhole camera are its simplicity and infinite depth of field, however it introduces vignetting. For a visible light pinhole camera one distinguishes natural vignetting following the cos4 law and mechanical vignetting due to finite thickness of the camera. For an X-ray pinhole camera one has to take into account an additional component of vignetting due to absorption of X-rays in the air or other gas unless the setup is kept in vacuum. The goal of this study is to work out an analytical model of vignetting effects for a FF-XRF apparatus using an X-ray pinhole camera. Complete quantitative characterisation of the vignetting effects is a key step towards proper correction of the vignetting artefacts in recorded images. The elaborated analytical model has been applied to the images acquired with the FF-XRF apparatus being developed and an example of vignetting correction is presented.

中文翻译：

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基于针孔光学的全场X射线荧光成像系统渐晕效应建模

摘要 全场X射线荧光（FF-XRF）成像是一种能够分析样品中元素空间分布的技术。另一种技术是扫描宏 XRF 方法。这两种技术都是对艺术品（主要是历史绘画）进行无损分析的强大工具。从技术上讲，FF-XRF成像通常是通过针孔相机与位置敏感和能量色散X射线探测器的耦合来实现的。针孔相机的主要优点是其简单性和无限景深，但它引入了渐晕。对于可见光针孔相机，由于相机的厚度有限，可以区分遵循 cos4 定律的自然渐晕和机械渐晕。对于 X 射线针孔相机，除非设置保持在真空中，否则由于在空气或其他气体中吸收 X 射线，必须考虑渐晕的附加分量。本研究的目的是为使用 X 射线针孔相机的 FF-XRF 设备制定渐晕效应分析模型。对渐晕效果进行完整的定量表征是正确校正记录图像中渐晕伪影的关键步骤。详细的分析模型已应用于使用正在开发的 FF-XRF 设备获取的图像，并提供了一个渐晕校正示例。对渐晕效果进行完整的定量表征是正确校正记录图像中渐晕伪影的关键步骤。详细的分析模型已应用于使用正在开发的 FF-XRF 设备获取的图像，并提供了一个渐晕校正示例。对渐晕效果进行完整的定量表征是正确校正记录图像中渐晕伪影的关键步骤。详细的分析模型已应用于使用正在开发的 FF-XRF 设备获取的图像，并提供了一个渐晕校正示例。