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X-ray gratings for Talbot Lau interferometry

Recent updates
High contrast resolution targets for X-ray imaging now available. (4.2021)
X-ray lenses: compound refractive lens (CRL). User publication list (excerpts) added! (7.2020)
X-ray gratings for Talbot interferometry. User publication list (excerpts) added! (6.2020)

Meet us at:
XNPIG International Conference on X-ray and Neutron Phase Imaging with Gratings
20-24.10.2019, Sendai International Center, Sendai, Japan
NSRRC Users' Meeting and Workshop
17-20.9.2019, NSRRC, Hsinchu, Taiwan

1. X-ray imaging by Talbot Interferometry

(a) X-ray images you can obtain
Using X-ray Talbot interferometer, differential phase contrast images and visibility contrast (dark field or small-angle scattering contrast) images can be obtained in addition to ordinary X-ray absorption images on one set-up, which allows you to get far more information of the inside and surface of the sample than the conventional X-ray absorption imaging method.
In the example images below, you will find the difference of the obtained information between the different modalities (absorption contrast and differential phase contrast) of the same sample taken at the same time.


Absorption contrast image

Differential phase contrast
Sample: SD card with scratches (scale bar: 2.5 mm). Taken at BL14-C, Photon Factory, Japan


In the example pictures below you find a differential phase contrast image and small-angle scattering image (dark field image) of a piece of old rubber tube. The dark field imaging is highly sensitive to structural change and density changes of tissues like lungs and can identify lung diseases where conventional X-ray imaging cannot do. Now, intensive efforts are geared at the realisation of medical equipments using the Talbot-Lau interferometry for imaging breast and lung diseases.

Differential phase contrast image

Small angle scattering image (dark field image)
Sample: old rubber tube (scale bar: 2.5 mm). Taken at BL14-C, Photon Factory, Japan




(b) Talbot Interferometer: Multi modal X-ray imaging method using X-ray gratings

By adding a source grating (absorption grating) G0 to a Talbot interferometer set-up, coherent X-ray can be obtained from a standard X-ray tube (Talbot-Lau interferometer).



Talbot-Lau interferometry system (TALINT)
set-up example:

- Energy: 8-60 keV (ask us for higher energies)
- FOV: Up to 10 mm round (with bent gratings)
- Visibility: > 25% (typ.)
- Source to detector distance: min. 500 mm
- Sensitivity ((G1-G2)/p2): ~250,000
- System phase drift: < 3 rad/h (with G2 period of 4.8 µm)



2. X-ray gratings from Karlsruhe, Germany

Karlsruhe Institute of Technology (KIT)/IMT and its spin-off company microworks GmbH have a long experience in the fabrication of micro structures by X-ray lithography and electroplating (LIGA process) and they supply worldwide high aspect ratio X-ray gratings necessary for Talbot interferometer.


Left: High aspect ratio absorption grating. AR > 80 available depending on the period.

Right: Bent absorption grating to avoid shadow effects. Delivered mounted on a holder.

(a) Grating structure examples
X-ray gratings are made by copying the precision structure of an X-ray mask onto the resist on the substrate, followed by electroplating done between the gaps of the X-ray exposed resist lamellae. Grating layout designs can either be chosen from existing masks or be newly made for your special set-up.


Metal height (examples)250 μm4.0 μm
Period (metal + space)4.8 μm3.57 μm
MaterialAuNi

Examples of existing period designs, subject to change



(b) Grating standard specifications

Here are some examples of grating specifications and some options which do not require special development.

Absorber / Phase shift materialAu, Ni or polymer resist
Substrate Standard: Si wafer (200 or 550 µm)
Optional: Low X-ray absorption materials like graphite and polyimide.
Structured area Standard: 70 mm diameter.
Optional: 100-140 mm diameter, 100 mm x 90 mm.
Further larger area by stitching some plates.
See also bleow, "(c) Development 1 / Large area gratings".


(c) Development 1 / Large area gratings
With some limited grating periods and structural heights, the large X-ray absorption gratings resulting in a large FOV have been realised.
Specs example Area: 200 mm x 100 mm
Grating period: 7.0-10.0 µm
Gold absorber thickness: 250 µm
Substrate material: Si
Note: Structures with bridges


(d) Development 2 / Very narrow period gratings for hard X-ray

Gratings for hard X-ray with very narrow periods of 1.0 to 2.0 µm are realised in some limited structure areas.




Period2.0 μm1.0 µm1.4 µm
Metal materialNiAuAu
Structure height3.2 μmUp to 5 µm> 20 µm
Structured area10 mm x 10 mm5 mm x 5 mm20 mm x 20 mm
Can be used asG1 (phase grating),18 keV,π/2G1,26 keV,π/2Absorption grating
Substrate materialPolyimideSi 200 µmPolyimide and others
Structure designContinuous lineBridgeBridge

3. Manufacturers and recent results

Manufacturers
Karlsruhe Institute of Technology (KIT)/IMT and its spin-off company microworks GmbH supply X-ray gratings for Talbot and Talbot-Lau interferometers not only with standard specifications described above but also with ones based on the customers' special requirements. ASICON Tokyo Ltd. serves as their local distributor and as technical partner of customers in Japan, South Korea and Taiwan.

High Aspect Ratio (High AR) structures
KIT/IMT and microworks GmbH are two of the world's top authorities in the fabrication of high aspect ratio polymer and metal structures using X-ray lithography and electroplating techniques. With these techniques (LIGA Process), X-ray gratings with both a narrow period and high aspect ratio have been realised.


Imaging examples
Internal link (Japanese): X-ray images of some samples taken with X-ray gratings fabricated by microworks GmbH.

4. Interested? Then contact us.

We will be happy to assist you with imaging of your samples, establishment of Talbot-Lau interforometry set-up, and optimisation of X-ray grating designs and their sales. Please feel free to contact us by email.


5. Publications by users of X-ray grating made by KIT/IMT and microworks (excerpts)

[Medical applications]
▶X-ray dark-field imaging of the human lung - A feasibility study on a deceased body. K Willer et al., PLoS One. 2018; 13(9): e0204565
▶Depiction of pneumothoraces in a large animal model using x-ray dark-field radiography. K Hellbach, A Baehr, F De Marco et al., Sci Rep 8, 2602 (2018)
▶A preclinical Talbot-Lau prototype for x‐ray dark‐field imaging of human‐sized objects. C Hauke et al., Med. Phys. 45 (6), June 2018

[Industrial applications]
▶Laboratory-based X-ray phase-imaging scanner using Talbot-Lau interferometer for non-destructive testing. Shivaji Bachche et al., Scientific Reports volume 7, Article number: 6711 (2017)
▶X-ray phase-imaging scanner with tiled bent gratings for large-field-of-view nondestructive testing. M Kageyama et al., NDT and E International 105 (2019) 19-24
▶System design and evaluation of a compact and high energy X-ray Talbot-Lau grating interferometer for industrial applications. Lee, S., Oh, O., Kim, Y. et al., J. Korean Phys. Soc. 73, 1827-1833 (2018)
▶Multi-modal Talbot-Lau grating interferometer XCT data for the characterization of carbon fibre reinforced polymers with metal components. C Gusenbauer et al., Conference on Industrial Computed Tomography (iCT) 2017

[Astrophysics]
▶Sub-arcsecond imaging with multi-image X-ray interferometer module (MIXIM) for very small satellite. Kiyoshi Hayashida et al., Proc. of SPIE Vol. 10699 106990U-1
▶「サブ秒角撮像を目指すX線多重像干渉計MIXIMの基礎開発」,川端智樹, 大阪大学大学院 修士論文 2018年2月
▶Sub-arcsecond to micro-arcsecond resolution X-ray imaging of SMBH with a novel method MIXIM, Kiyoshi Hayashida et al., AGN Jet Workshop, 2020
X線光学製品と微細加工技術LIGA
X-ray optics and micro fabrication (LIGA)

マイクロ流体デバイス
Microfluidic devices