Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Laboratory breakthrough may lead to improved X-ray spectrometers


Swiss researchers improve an interferometry technique by utilizing the interference fringe, an aspect previously viewed as a nuisance

Researchers at the Paul Scherrer Institute's Swiss Light Source in Villigen, Switzerland, have developed a new design for X-ray spectrometers that eschews a commonly utilized component to lowers overall production costs and increase the efficiency of x-ray flux, which may lead to faster acquisition times for sample imaging and increased efficiency for the system. This is essential for biological samples which may be damaged by continued x-ray exposure.

Directly resolved micro-meter interference fringes help reveal subtle phase contrast in the sample.

Credit: Kagias/PSI

X-ray grating interferometry is an extremely useful tool for investigating the compositions of unknown biological samples. In the traditional setup, a source of interference called the interference fringe necessitated the use of highly-sensitive detectors. In response to this, a method known as Talbot-Lau interferometry was developed and widely adopted. It renders the detector mostly inessential by decoupling the interferometer's sensitivity from the detector's resolution. However, a number of manufacturing costs and mechanical complexities ultimately complicate its implementation.

To remedy this, researchers at the Institute for Biomedical Engineering in Zurich and the Swiss Light Source (SLS) have developed an interferometer which does not use the traditional component, called a G2 grating, and instead directly exploits the fringe interference for higher resolution.

"We can perform differential phase contrast imaging with high sensitivity without the need for a G2 grating or a detector with small pixel size in order to resolve the fringe," said Matias Kagias. Kagias is a PhD student in the laboratory of Marco Stampanoni, the paper's primary investigator. Kagias and his colleagues present their work this week in Applied Physics Letters, from AIP Publishing.

X-ray interferometry works by firing X-rays at a downstream detector. When a biomedical sample or a piece of material is placed in the beam's path, the object modifies the observed interference pattern via absorption, refraction, and small-angle scattering. Once these signals are picked up by the detector, technicians can determine the sample's properties using an algorithm.

Along the way - either before or after the sample - the beams pass through a phase grating, which divides the beam into different diffraction orders based on their wavelength. The difference between these diffraction orders introduces an interference fringe - a problematic source of interference which needs to be in the micrometer range in order to achieve high sensitivity for the detector. Unfortunately, such fringes are challenging to record directly over a large field of view.

To work around this, the Talbot-Lau interferometry method utilizes an absorption grating, G2, placed right before the detector, and senses the distortions by a procedure known as phase stepping. Here, the absorption grating is scanned step by step for one or more periods of the interference fringe, each time recording an image which results in an intensity curve at each pixel. This allows the interference fringe to be sensed indirectly, while obtaining absorption, differential phase and small-angle scattering signals for each pixel.

However, this ultimately causes the system to be less efficient for each dose of x-rays due to photon absorption by G2. The required area and aspect ratio of the gratings, which are millimeter-sized, further complicate matters by driving up overall production costs.

The researchers' experimental setup consisted of an X-ray source, a single phase grating, and a GOTTHARD microstrip detector developed by the SLS detector group - a significantly simplified version of the traditional Talbot-Lau interferometer. The GOTTHARD detector uses a direct conversion sensor, in which X-ray photons are absorbed , the charge generated from one absorption event is collected by more than one channel for small channel sizes - charge sharing.

"The key point to resolving the fringe is to acquire single photon events and then interpolate their positions using the charge sharing effect, which is usually considered as a negative effect in photon counting detectors," Kagias said. By interpolating the position of many photons, a high resolution image can then be acquired.

When the researchers implemented the appropriate algorithm to analyze this recorded fringe, they found that the fringes of a few micrometers could be acquired successfully while still retrieving the differential phase signal.

According to Kagias, this ultimately increases the interferometer's flux efficiency by a factor of 2 compared to a standard Talbot-Lau interferometer. This may lead to faster acquisition times and a dose reduction, which is essential given X-rays' potential to damage biological structures.

Future work for Kagias and his colleagues involves moving to large area pixel detectors, and improving the resolution and sensitivity of their setup.


The article, "Single Shot X-Ray Phase Contrast Imaging Using a Direct Conversion Microstrip Detector with Single Photon Sensitivity" is authored by M. Kagias, S. Cartier, Z. Wang, A. Bergamaschi, R. Dinapoli, A. Mozzanica, B. Schmitt, and M. Stampanoni. It will appear in the journal Applied Physics Letters on June 7, 2016 (DOI: 10.1063/1.4948584). After that date, it can be accessed at:

About the journal:

Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology.

Media Contact

John Arnst


John Arnst | EurekAlert!

Further reports about: Applied Physics G2 X-ray biological samples detector spectrometers

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>