On-line X-ray focal spot assessment based on deconvolution using standard imaging devices

This article deals with micro-focus X-ray imaging in high resolution non-destructive testing applications. We present a new technique to assess on-line the focus shape using standard digital radioscopic devices. The focal spot is recovered using a deconvolution technique of the point spread function. A theoretical study based on radiation physics is carried out to determine the optimal material for the test object. We show that the minimum magnification and the detector's spatial cut-off frequency must be directly linked to the deconvolution regularization term. The proposed method is reliable, and does not required any assumption as regards the focus shape. Results are compared to former or existing standards, and to a Gaussian analytical model. (C) 2003 Elsevier Science Ltd. All rights reserved.