Ralf K. Heilmann

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The Constellation-X mission will perform X-Ray science with improvements in energy resolution and effective area over its predecessor missions. The primary instrument on each of the four Constellation-X spacecraft is the Spectroscopy X-Ray Telescope (SXT). The SXT is a 1.6m diameter grazing incidence mirror assembly comprised of approximately 4000 optic(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 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)
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 Reflection Grating Spectrometer (RGS) on Constellation-X will require thousands of large gratings with very exacting tolerances. Two types of grating geometries have been proposed. In-plane gratings have low ruling densities (∼ 500 l/mm) and very tight flatness and assembly tolerances. Off-plane gratings require much higher ruling densities (∼ 5000(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)
The analysis of many systems in optical communications and metrology utilizing Gaussian beams, such as free-space propagation from single-mode fibers, point diffraction interferometers, and interference lithography, would benefit from an accurate analytical model of Gaussian beam propagation. We present a full vector analysis of Gaussian beam propagation by(More)
We present a spectrometer design based on a novel nanofabricated blazed X-ray transmission grating which is modeled to have superior efficiency. Here we outline a full instrument design proposed for Constellation-X which is expected to give resolving powers ~2000 (HEW). The spectrometer advantages include lower mass budget and smaller diffractor area, as(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)