On the resolution and linearity of lensless in situ X-ray beam diagnostics using pixelated sensors

Abstract

We present a theoretical model that describes the resolution and linearity of a novel transparent X-ray beam imaging and position measurement method. Using a pinhole or coded aperture camera with pixelated area sensors to image a small fraction of radiation scattered by a thin foil placed at oblique angles with respect to the beam, a very precise measurement of the beam position is made. We show that the resolution of the method is determined by incident beam intensity, beam size, camera parameters, sensor pixel size and noise. The model is verified experimentally showing a sub-micrometer resolution over a large linear range.

Performance of the Lancelot Beam Position Monitor at the Diamond Light Source

“…The cross-shaped aperture in the I19 Lancelot module is ideal for low intensity beamlines as it allows more scattered photons to reach the sensor. Additionally, the signal-to-noise ratio increases significantly when using a cross-shaped aperture [7]. However, the measured image in figure 4 is a convolution of the aperture shape with that of the beam.…”

“…The Lancelot beam position and profile monitor [6,7] places a thin foil of low-Z material in the path of the beam. This material causes a negligible drop in flux downstream of the monitor and does not introduce any absorption edges in the hard X-ray part of the spectrum.…”

Compact integrated X-ray intensity and beam position monitor based on rare gas scintillation

“…X-ray scattering from thin films is also used to measure intensity in an unobtrusive way. Silfhout et al [1][2][3][4][5][6] have enhanced scattering-based intensity monitoring by imaging the X-ray footprint using arrays of Soller slits or pinholes in combination with a PIN diode array or CCD imaging device. Most relevant to the work reported here, Suzuki et al 9 have developed a high intensity X-ray monitor based upon the scintillation of the Ar gas.…”