A USB 3.0 readout system for Timepix3 detectors with on-board processing capabilities

Self Cite

Elemental mapping images can be achieved through step scanning imaging using pinhole optics or micro pore optics (MPO), or alternatively by full-field X-ray fluorescence imaging (FF-XRF). X-ray optics for FF-XRF can be manufactured with different micro-channel geometries such as square, hexagonal or circular channels. Each optic geometry creates different imaging artefacts. Square-channel MPOs generate a high intensity central spot due to two reflections via orthogonal channel walls inside a single channel, which is the desirable part for image formation, and two perpendicular lines forming a cross due to reflections in one plane only. Thus, we have studied the performance of a square-channel MPO in an FF-XRF imaging system. The setup consists of a commercially available MPO provided by Photonis and a Timepix3 readout chip with a silicon detector. Imaging of fluorescence from small metal particles has been used to obtain the point spread function (PSF) characteristics. The transmission through MPO channels and variation of the critical reflection angle are characterized by measurements of fluorescence from copper and titanium metal fragments. Since the critical angle of reflection is energy dependent, the cross-arm artefacts will affect the resolution differently for different fluorescence energies. It is possible to identify metal fragments due to the form of the PSF function. The PSF function can be further characterized using a Fourier transform to suppress diffuse background signals in the image.

Section: Timepix3 Pixel Detectormentioning

confidence: 99%

Characterization of micro pore optics for full-field X-ray fluorescence imaging

Krapohl

Thörnberg

et al. 2023

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“…In conventional flat field correction, projection images without sample are acquired with and without radiation, which are referred to as flat fields (F) and dark fields (D). In this case, the dark field is not required since Timepix3 is a threshold-based detector that does not record any counts below threshold [34]. Thus, a flat-field image of a Cu plate was obtained and implemented.…”

Section: Xrf Image Of Euro Coinmentioning

confidence: 99%

“…The hybrid pixel detectors emerged from the technology developed for high-energy physics experiments, which can be considered as an assembly of thousands of independent point detectors. The Timepix3, a hybrid pixel detector developed by the Medipix3 group at CERN [24] [25], is a general-purpose integrated circuit suitable for readout of both semiconductor detectors and gas-filled detectors. Unlike in a CCD detector where all pixels share one charge-to-voltage convertor, in a hybrid pixel detector, each pixel has its individual sensitive amplifier, resulting in a fast charge digitization.…”

Section: Introductionmentioning

confidence: 99%

Full-field X-ray fluorescence imaging with a straight polycapillary X-ray collimator

An¹,

Krapohl²,

Norlin³

et al. 2020

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Due to the availability of X-ray imaging detectors, full-field X-ray fluorescence (FF-XRF) imaging technique has become achievable, which provides an alternative to scanning Xray fluorescence imaging with a micro-focus X-ray beamline. In this paper, we present a setup based on straight capillary optics and an energy-dispersive hybrid pixel detector, which can perform simultaneous mapping of several chemical elements. The photon transmission efficiency and spatial resolution are compared between two X-ray collimation setups: one using pinhole optics and one using straight polycapillary optics. There is a tradeoff between the spatial resolution and transmission efficiency when considering X-ray optics. When optimizing the spatial resolution, using straight capillary optics achieved a higher intensity gain when comparing with the pinhole setup. Characterization of the polycapillary imaging setup is performed through analyzing various samples in order to investigate the spatial-frequency response and the energy sensitivity. This developed setup is capable of FF-XRF imaging in characteristic energies below 20 keV, while for higher energies the spatial resolution is affected by photon transmission through the collimator. This work shows the potential of the FF-XRF instrument in the monitoring of toxic metal distributions in environmental mapping measurements.

“…Finally, the MTF is obtained via Fourier transformation of the LSF. The resulting MTF is truncated using the FWHM obtained by applying a Gaussian fit to the LSF [13][14][15].…”

Section: Image Quality Analysismentioning

confidence: 99%

Super-resolution X-ray imaging with hybrid pixel detectors using electromagnetic source stepping

Dreier¹,

Lundström

Bech³

2020

Self Cite

With increasing demand for high-resolution X-ray images, the super-resolution method allows to estimate a single high-resolution image from several low-resolution images. Hybrid pixel detectors provide high-quality and low-resolution images, which makes them particularly well suited for super-resolution. However, such detectors consist of a limited number of pixels at high cost. Applying super-resolution with hybrid pixel detectors shows that it is a viable method to obtain high-resolution images. The point-spread function of such detectors can be idealised to be 1 pixel, adding no blur into the image making such detectors the ideal choice for the application of super-resolution X-ray imaging. However, there are charge sharing effects between the pixels caused by the energy and impact position of incoming photons. Utilising an X-ray source, which allows magnetic stepping of the X-ray spot, several slightly shifted images can be obtained without requiring mechanical movements. Registering the shifts between individual images with sub-pixel precision allows to estimate a high-resolution image. With repeatable and equally spaced X-ray spot position patterns, sufficient information can be obtained with only a few images. In this paper, we present the application of super-resolution for X-ray imaging using a Pilatus 100K hybrid pixel detector from Dectris Ltd. and a prototype micro-focus X-ray source from Excillum AB. Moreover, we analyse the image quality for applications in X-ray radiography and tomography. Using a sufficient number of low-resolution images allows us to achieve an increase in resolution, without introducing significant blur or artefacts into the image. Here we quantify the effects on the quality of resulting super-resolution images using different methods of image interpolation, interpolation factors, shifts of the sample on the detector, and amount of low-resolution images.