Dr. Frank Allenstein Profile

Dr. Frank Allenstein

Senior Development Engineer at Meyer Burger (Germany) AG

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Publications (2)

Proceedings Article | 25 August 2010 Paper

Ion-beam figuring (IBF) for high-precision optics becomes affordable

Sven Kiontke, Marcel Demmler, Michael Zeuner, Frank Allenstein, Thoralf Dunger, Matthias Nestler

Proceedings Volume 7786, 77860F (2010) https://doi.org/10.1117/12.859127

KEYWORDS: Ion beams, Ion beam finishing, Aspheric lenses, Surface finishing, Manufacturing, Polishing, Precision optics, Optical components, Ions, Lenses

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Proceedings Article | 16 February 2010 Paper

Ion beam figuring (IBF) for high precision optics

Marcel Demmler, Michael Zeuner, Frank Allenstein, Thoralf Dunger, Matthias Nestler, Sven Kiontke

Proceedings Volume 7591, 75910Y (2010) https://doi.org/10.1117/12.840908

KEYWORDS: Ion beams, Ion beam finishing, Etching, Polishing, Spatial frequencies, Ions, Optical components, Optics manufacturing, Precision optics, Surface finishing

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Recently and upcoming optical applications depend more and more on the precision of the optical elements used. The last is especially driven by shorter wavelength, higher flux densities and imaging close to the diffraction limit. Therefore a dramatically increasing demand on high precision and high quality optical components in leading edge equipment as well as common devices and instruments is observed. So far a few methods have been introduced to provide an adequate manufacturing performance using mechanical grinding and polishing techniques. Up to now the very sophisticated ion beam figuring (IBF) has not been used for common optics. The reasons for this might be the perception of higher costs and less knowledge about the technique in the industry. Now an affordable ion beam figuring technique has been developed to address precision aspherical optics applications. This paper introduces ion beam figuring technology based on equipment which is widely used in semiconductor mass production for ultra precise film thickness trimming. Ion beam figuring works by raster-scanning a focused broad ion beam across an optical surface with variable velocity and dwell time in order to precisely and locally trim away surface contour errors. As a new and cost effective approach the ion beam figuring system used in this presentation applies a 3 axis movement system only (compared to expensive 5-axis movements in other applications). X-and y-axes are used for the areal scan, and the z-axis is used for focus adjustment due to the surface contour of the optical element. The system was intentionally designed without the 2 additional tilt axes for incident angle adjustment and cleverly reduces the complexity and size of the system. It is shown that curved spherical or aspherical surfaces can be corrected down to λ/50 or better by using the state of the art 3-axes trimming system. Even with high spatial frequency parts final processing qualities better than λ/10 are achieved.

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