Ralf K Heilmann

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Metrology is the science and engineering of measurement. It has played a crucial role in the industrial revolution at the milli-inch length scale and in the semiconductor revolution at the micrometre length scale. It is often proclaimed that we are standing at the threshold of another industrial revolution, brought by the advent and maturing of(More)
The authors report a silicon-on-insulator ͑SOI͒ process for the fabrication of ultrahigh aspect ratio freestanding gratings for high efficiency x-ray and extreme ultraviolet spectroscopy. This new grating design will lead to blazed transmission gratings via total external reflection on the grating sidewalls for x rays incident at graze angles below their(More)
Diffraction gratings are ubiquitous wavelength dispersive elements for photons as well as for subatomic particles, atoms, and large molecules. They serve as enabling devices for spectroscopy, microscopy, and interferometry in numerous applications across the physical sciences. Transmission gratings are required in applications that demand high alignment and(More)
The authors report on the fabrication of 200 nm period blazed transmission gratings on silicon-on-insulator ͑SOI͒ wafers. These critical angle transmission ͑CAT͒ gratings require 3 – 5 ␮m tall freestanding grating bars with a very high aspect ratio ͑Ͼ100͒ and smooth sidewalls. In order to meet the challenging geometrical requirements, they modified and(More)
We report progress in using nanoimprint lithography to fabricate high fidelity blazed diffraction gratings. Anisotropically etched silicon gratings with 200 nm period and 7.5° blaze angle were successfully replicated onto 100 mm diameter wafers with subnanometer roughness and excellent profile conformity. Out-of-plane distortion induced by residual stress(More)
We have developed a new type of soft x-ray diffraction grating. This critical-angle transmission (CAT) grating combines the advantages of traditional transmission gratings (low mass, extremely relaxed alignment and flatness tolerances) with those of x-ray reflection gratings (high efficiency due to blazing in the direction of grazing-incidence reflection,(More)
We report a process which integrates interference lithography, nanoimprint lithography, and anisotropic etching to fabricate replicated diffraction gratings with sawtooth profiles. This new process greatly reduces grating fabrication time and cost, while preserving the groove shape and smoothness. Relief gratings with 400 nm period inverted triangular(More)
High-resolution spectroscopy at energies below 1 keV covers the lines of C, N, O, Ne and Fe ions, and is central to studies of the Interstellar Medium, the Warm Hot Intergalactic Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, etc. The large collecting area, long focal length, and 5 arcsecond half power diameter(More)
  • Ralf K Heilmann, Glen P Monnelly, Olivier Mongrard, Nat Butler, Carl G Chen, Lester M Cohen +6 others
  • 2003
We report on progress in developing low-cost methods for shaping thin-foil glass x-ray optics. Such optics might serve as substrates for reflection gratings or as foil mirrors in high-throughput missions such as Constellation-X. Novel thermal shaping to lithographically defined pin chucks leads to the desired shape with high accuracy, thereby avoiding the(More)
We are developing scanning beam interference lithography ͑SBIL͒ for writing and reading large gratings with nanometer level distortion. Our distortion goals require fringe locking to a moving substrate with subnanometer spatial phase error while measuring and controlling the fringe period to approximately one part per million. In this article, we describe(More)