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Showing papers in "Proceedings of SPIE in 1990"


Proceedings ArticleDOI
TL;DR: In this paper, a parametric influence on the morphology of CVD diamond has been investigated, where the surface of diamond films changes from the triangular 1 1 1 ) faces to the square f 100) faces.
Abstract: A parametric influence on the morphology of CVD diamond has been investigated. While the gas pressure has a minor effect on the morphological development of diamond in the optimum temperature range, the influences by the substrate temperature, the methane concentration in hydrogen, and the gas flow rate are found to be substantial. With an increase of substrate temperature or gas flow rate over the range in this study, the surface of diamond films changes from the f 100) face dominating to the { 1 1 1 } face prevailing. With an increase of methane concentrations from 0.5% to 2%, the morphology of diamond films changes from the triangular 1 1 1 ) faces to the square f 100) faces. Further increasing methane concentrations to 5% results in a film with sub-.tm crystallite aggregates. These experimental variables change the diamond morphology possibly by influencing the free energies of crystallographic faces and the atom mobility on the surface.

11 citations


Proceedings ArticleDOI
TL;DR: In this paper, the first prototypes have been 6 mm or 20 mm diameter windows with film thicknesses 0.5 micrometers - 2.5 mm of polyimide and 40 nm - 100 nm of aluminum.
Abstract: Methods have been developed to make ultrathin low-leak x-ray entrance windows which can withstand atmospheric pressures. The first prototypes have been 6 mm or 20 mm diameter windows with film thicknesses 0.5 micrometers - 2.5 micrometers of polyimide and 40 nm - 100 nm of aluminum. Also 0.5 micrometers - 1 micrometers thick beryllium windows with diameter of 6 mm have been fabricated. The goal is to fabricate 140 mm and 70 mm diameter windows for Danish-Finnish position sensitive proportional counters to be flown on the Soviet SPECTRUM-ROENTGEN-GAMMA satellite.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

5 citations


Proceedings ArticleDOI
TL;DR: In this article, the angle-resolved scattering from several phase Fresnel zone plates (lenses) and Dammann gratings (beam splitters) was calculated by random perturbations of the surface-relief pattern.
Abstract: We have calculated the angle-resolved scattering from several phase only Fresnel zone plates (lenses) and Dammann gratings (beam splitters). We simulate manufacturing errors by random perturbations of the surface-relief pattern, and calculate the irradiance in the far-field by evaluating the Fresnel diffraction integral. Scattering from perturbations of the etch depth is found to be proportional to the square of the ratio of the perturbation divided by the wavelength. Random perturbations of the pattern edges in Fresnel zone plates causes more scattering with shorter wavelengths than with longer wavelengths, but in Dammann gratings this scattering is independent of wavelength. Scattering increases for either small apertures or small f-numbers; but does not depend on either the number of levels in a Fresnel zone plate, the pattern in a Dammann grating, or the form of the probability distribution function.

4 citations