Mr. Herman A. Combrinck Profile

Herman A. Combrinck

Process Development Engineer at Cranfield Precision

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Publications (4)

Proceedings Article | 20 November 2017 Open Access

Design and development by direct polishing of the WFXT thin polynomial mirror shells

L. Proserpio, S. Campana, O. Citterio, M. Civitani, H. Combrinck, P. Conconi, V. Cotroneo, R. Freeman, E. Mattini, P. Langstrof, R. Morton, G. Motta, O. Oberle, G. Pareschi, G. Parodi, C. Pels, C. Schenk, R. Stock, G. Tagliaferri

Proceedings Volume 10565, 105652N (2017) https://doi.org/10.1117/12.2309176

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Proceedings Article | 27 September 2012 Paper

Thin glass shell oriented to wide field x-ray telescope

M. Civitani, O. Citterio, S. Campana, P. Conconi, E. Mattaini, G. Pareschi, G. Tagliaferri, G. Parodi, V. Burwitz, G. Hartner, J. Arnold, S. Schuler, H. Combrinck, R. Freeman, R. Morton, P. Simpson, D. Walker

Proceedings Volume 8443, 84430Q (2012) https://doi.org/10.1117/12.925906

KEYWORDS: X-rays, Calibration, X-ray telescopes, Polishing, Glasses, Atomic force microscopy, Sensors, Silica, Mirrors, Metrology

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Proceedings Article | 12 October 2011 Paper

Progress on precise grinding and polishing of thin glass monolithic shell (towards WFXT)

O. Citterio, M. Civitani, J. Arnold, S. Campana, H. Combrinck, P. Conconi, V. Cotroneo, R. Freeman, E. Mattaini, R. Morton, G. Motta, G. Pareschi, G. Parodi, L. Proserpio, S. Schuler, P. Simpson, G. Tagliaferri, D. Walker

Proceedings Volume 8147, 814714 (2011) https://doi.org/10.1117/12.895309

KEYWORDS: Polishing, Mirrors, Surface finishing, Glasses, Silica, X-ray telescopes, X-rays, Spatial resolution, Off axis mirrors, Manufacturing

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Proceedings Article | 29 July 2010 Paper

Design and development of thin quartz glass WFXT polynomial mirror shells by direct polishing

L. Proserpio, S. Campana, O. Citterio, M. Civitani, H. Combrinck, P. Conconi, V. Cotroneo, R. Freeman, P. Langstrof, E. Mattaini, R. Morton, B. Oberle, G. Pareschi, G. Parodi, C. Pels, C. Schenk, R. Stock, G. Tagliaferri

Proceedings Volume 7732, 77320D (2010) https://doi.org/10.1117/12.857418

KEYWORDS: Mirrors, Polishing, Quartz, Glasses, Metrology, X-ray telescopes, X-rays, Surface finishing, Spatial resolution, Silicon carbide

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The Wide Field X-ray Telescope (WFXT) is a medium class mission for X-ray surveys of the sky with an unprecedented area and sensitivity. In order to meet the effective area requirement, the design of the optical system is based on very thin mirror shells, with thicknesses in the 1-2 mm range. In order to get the desired angular resolution (10 arcsec requirement, 5 arcsec goal) across the entire 1x1 degree FOV (Field Of View), the design of the optical system is based on nested modified grazing incidence Wolter-I mirrors realized with polynomial profiles, focal plane curvature and plate scale corrections. This design guarantees an increased angular resolution at large off-axis angle with respect to the normally used Wolter I configuration, making WFXT ideal for survey purposes. The WFXT X-ray Telescope Assembly is composed by three identical mirror modules of 78 nested shells each, with diameter up to 1.1 m. The epoxy replication process with SiC shells has already been proved to be a valuable technology to meet the angular resolution requirement of 10 arcsec. To further mature the telescope manufacturing technology and to achieve the goal of 5 arcsec, a deterministic direct polishing method is under investigation. The direct polishing method has already been used for past missions (as Einstein, Rosat, Chandra): the technological challenge now is to apply it for almost ten times thinner shells. Under investigation is quartz glass (fused silica), a well-known material with good thermo-mechanical and polishability characteristics that could meet our goal in terms of mass and stiffness, with significant cost and time saving with respect to SiC. Our approach is based on two main steps: first quartz glass tubes available on the market are grinded to conical profiles, and second the obtained shells are polished to the required polynomial profiles by CNC (Computer Numerical Control) polishing machine. In this paper, the first results of the direct grinding and polishing of prototypes shells made by quartz glass with low thickness, representative of the WFXT optical design, are presented.

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