@inproceedings{5cf4a6f93938491d9adeda1c0f650a97,
title = "Front and backside structuring of gratings for phase contrast imaging with X-ray tubes",
abstract = "Phase contrast imaging with conventional X-ray tubes as e.g. in computer tomography scanners (CTscanners) requires a setup of three different types of optical gratings. One grating is used to obtain a spatially coherent radiation, the second grating defines a periodic phase shift and the third is used as a periodic absorption grating. In order to absorb high energy radiation, absorption gratings with periods of a few microns only and extreme aspect ratios (>80) are fabricated, employing a modified LIGA process. However, above a critical structural height, structures collapse due to e.g. capillary effects. To overcome this limitation a new variant of the LIGA process has been developed. It is characterized by structuring of a resist on both sides of a membrane, resulting in a moderate aspect ratio on both sides of the membrane instead of an extreme aspect ratio on one side. To get a perfect overlay of both structures the grating structure on the front side of a membrane patterned by the standard LIGA-process is used as the mask for structuring the second resist layer on the backside of the membrane. A second electroforming step fills the gaps on the backside.",
keywords = "LIGA, Phase contrast, X-ray, computer tomography, extreme aspect ratio, grating, grating interferometry, talbot effect, talbot interferometer, talbot-lau interferometer",
author = "J. Kenntner and T. Grund and B. Matthis and M. Boerner and J. Mohr and T. Scherer and M. Walter and M. Willner and A. Tapfer and M. Bech and F. Pfeiffer and I. Zanette and T. Weitkamp",
year = "2010",
doi = "10.1117/12.859666",
language = "English",
isbn = "9780819483003",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
booktitle = "Developments in X-Ray Tomography VII",
note = "Developments in X-Ray Tomography VII ; Conference date: 02-08-2010 Through 05-08-2010",
}