Accredited NDT Test Lab

Department

Current research: L100 X-Ray line detector for fast in-line applications

Topic

L100 X-ray line detector, complete system.

Close-up of the active area of the L100: absorber (upper left) wire-bonded to the readout electronics (lower right).

In the context of a strategic alliance with Fraunhofer IPMS and Fraunhofer FEP, a novel X-ray line detector was developed. X-ray detectors are gradually replacing the X-ray films still common in radiography today and are essential for X-ray computed tomography. In conventional indirectly converting detectors, the incoming X-ray photons are converted into visible light, which is then converted into electrical signals by photodiodes for subsequent processing. The intermediate step of converting the X-ray photons into light photons has potentially negative effects on the detector‘s resolution and linearity. To overcome this difficulty, the L100 X-ray line detector presented here works as a directly converting detector, which means that the X-ray photons are directly converted into electrical signals in a kind of a photodiode.

The advantages of this concept are a significant improvement in resolution and linearity as well as the possibility of estimating the energy of each photon presented by the single-photon sensitivity, which in turn can be efficiently used for dual-energy applications, such as material sorting.

Line detectors are used when moving objects need to be analyzed or if the size of the test specimen only permits the use of a well-collimated illuminating beam for elimination of undesirable scattered radiation. The line detector developed in the present work is assembled using application-specific integrated circuits (ASICs) to enable low-cost manufacturing and high configuration flexibility.

The prototypes currently under test have a line length of 102.4 mm and achieve a resolution of 100 μm in test conditions. They can be constructed with two different kinds of absorber materials, enabling detection of X-ray photons in energy ranges of 30–200 keV and 2–40 keV. Thus, the X-ray line detector can be used for both imaging and diffraction applications. The minimum counting time of the detector is 20 μs, which makes it possible to examine the test objects at a speed of around 50 m/s (dependent on the test design).

Combined with the XVision X-ray computed tomography control and analysis software, customized X-ray microtomography systems with intuitive user interfaces can be constructed.