Penumbral imaging made easy

Abstract

A new and most direct method of penumbral imaging is presented. It is shown that for square (or polygonal) apertures, the source distribution is given by the second-order mixed Cartesian derivative of the penumbral image intensity distribution. Use of this approach is illustrated by computer simulation. Two different source sizes (3.2 mm and 10 pm) of high-energy gamma sources were reconstructed. The effect of noise in the recording system is studied and a simple noise reduction technique is shown to be quite effective.

Characterization of the self magnetic pinch diode at high voltages for flash radiography.

“…This hot core suggests that the resolving power of the SMP diode in this configuration are greater than given by the standard ESF measurement. The symmetry of the source can be measured by reconstructing a 2-d beam image of the source using the method of Barnea [11,12]. This reconstruction is shown in Fig.…”

“…In this case, if the source distribution were Gaussian, the value determined by the AWE definition and the LLNL definition would be equivalent. By having a co-planar 2-dimensional rolled edge it is possible to use the corner where the two edges meet to derive the spot distribution following the method of Barnea [11,12]. We have implemented a modified version of Barnea's methodology for a single corner and present results of spot size measurements in comparison with the standard penumbral-edge technique.…”

A stochastic approach to quantifying the blur with uncertainty estimation for high-energy X-ray imaging systems

“…[11] The magnification is given by m = l d /l s , where the conjugate distances, l s and l d , are the distances from the source to the aperture and from the aperture to the detector, respectively (see Figure 1). Equations (2) and (3) only affect scaling in the problem, and in practice they are corrected in post-processing.…”

“…A penumbral imaging [8][9][10] technique for spot reconstruction was introduced by Barnea in [11] and is based on the assumption that, when imaging a square aperture larger than the source, all of the information about the source is contained in the penumbra, or blur, caused by the leading edge of the aperture. Figure 1 shows a cartoon schematic of such a system, where the object being imaged is a so-called 'L Rolled Edge' (LRE), which has a square aperture with slightly beveled insides.…”

Demonstration of the self-magnetic-pinch diode as an X-ray source for flash core-punch radiography.

“…In this case, if the source distribution were Gaussian, the value determined by the AWE definition and the LLNL definition would be equivalent. By having a co-planar 2-dimensional rolled edge it is possible to use the corner where the two edges meet to derive the spot distribution by using the method of Barnea [11,12]. The method calls for taking derivatives of multiple line profiles at every corner of a four corner aperture.…”