Mr. Christian J. Trum Profile

Christian J. Trum

Project Engineer at Technische Hochschule Deggendorf

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Publications (11)

Proceedings Article | 20 August 2020 Poster + Paper

Hybrid-process-chain for polishing optical glass lenses – HyoptO

Christian Trum, Beate Schmidbauer, Rolf Rascher, Manuel Jung, Edgar Willenborg, Sebastian Sitzberger

Proceedings Volume 11487, 114871L (2020) https://doi.org/10.1117/12.2568400

KEYWORDS: Polishing, Surface finishing, Glasses, Laser processing, Silica, Lenses, Surface roughness

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Proceedings Article | 8 July 2020 Paper

Concept of a two-part clamping system for lenses in optical metrology

Sebastian Sitzberger, Rolf Rascher, Johannes Liebl, Christian Trum

Proceedings Volume 11478, 114780G (2020) https://doi.org/10.1117/12.2566547

KEYWORDS: Lenses, Interfaces, Metrology, Optical metrology, Manufacturing, Prototyping, Fused deposition modeling, Optical testing

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Proceedings Article | 8 July 2020 Paper

Non-ablative removal of sub surface damages in ground optical glass substrates by controlled melting of thin surface layers using CO2-laser radiation

Manuel Jung, Christian Trum, Beate Schmidbauer, Edgar Willenborg, Rolf Rascher

Proceedings Volume 11478, 1147804 (2020) https://doi.org/10.1117/12.2564801

KEYWORDS: Laser processing, Surface finishing, Silica, Polishing, Glasses, Surface roughness

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Proceedings Article | 14 September 2018 Presentation + Paper

Improved performance of CMP processes through targeted adjustment of polishing slurry and polish pad

Christian Trum, Sebastian Sitzberger, Rolf Rascher

Proceedings Volume 10742, 107420S (2018) https://doi.org/10.1117/12.2321031

KEYWORDS: Polishing, Surface finishing, Manufacturing, Materials processing, Optical components

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Chemical-mechanical polishing (CMP) of optical glasses is widespread and forms the basis for many high-precision polishing processes. The pads, slurries and glass materials used in polishing have many different properties. The effects of these properties on the process results are often unknown. The right choice and combination is therefore often a challenge.

By means of a plan processing of N-BK7 and SF56 samples by a plan-polishing process, the influence on the process results, material removal rate (MRR), micro roughness and cleanliness caused by slurry and polishing pad is shown. It turns out that the type of polish pad has the biggest impact on the results. The easy-to-process material N-BK7 shows only little influence by the type of slurry used. The more challenging SF56, however, shows significant effects, especially in the area of the resulting micro roughness and the appearance of surface damages like orange peel. Especially the use of Auerpol® PZ500 shows clear advantages here.

For a selection of three out of nine polishing pads, the effect of density variation of the slurry was also investigated. Lower particle concentrations lead to lower material removal rates. This applies to both materials. The more sensitive SF56 shows a reduction in micro roughness by the use of a less dense slurry.

The correct selection of the polishing pad has a positive effect on the material removal rate and/or the micro roughness in all tested materials. An adaptation of the type and concentration of the slurry is especially important for more sensitive materials and in combination with the right polishing pad.

In view of the development towards special materials and small lot sizes, the targeted and correct selection of polishing slurries and pads becomes more and more important. The information required for this purpose on the behavior of the pads and slurries available on the market must therefore first be determined in a targeted manner and clearly presented.

Proceedings Article | 7 August 2018 Paper

Filled-Up-Microscopy (FUM): a non-destructive method for approximating the depth of sub-surface damage on ground surfaces

Christian Trum, Christian Vogt, Sebastian Sitzberger, Rolf Rascher, Oliver Faehnle

Proceedings Volume 10829, 1082909 (2018) https://doi.org/10.1117/12.2318576

KEYWORDS: Cements, Nondestructive evaluation, Confocal microscopy, Light scattering, Microscopy, Surface finishing, Manufacturing, Polishing, Optics manufacturing, Laser induced damage

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Proceedings Article | 7 August 2018 Paper

Workpiece self-weight in precision optics manufacturing: compensation of workpiece deformations by a fluid bearing

Sebastian Sitzberger, Christian Trum, Rolf Rascher, Michael Zaeh

Proceedings Volume 10829, 108290A (2018) https://doi.org/10.1117/12.2318577

KEYWORDS: Lenses, Optics manufacturing, Interfaces, Precision optics, Interferometers, Manufacturing, Adhesives, Metrology

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The effects, the extent and the importance of workpiece deformations, particularly lenses, caused by the weight of the workpiece itself, were examined in a previous paper¹ . The considered deformations are in the single-digit to two-digit nanometer range. The investigation was carried out by FEM calculations. The conclusion of the previous aper was that a full-surface support of a workpiece in the processing of one surface presumably produces the best results. Furthermore, it was found that if the second functional surface is not to be touched in the process, a full contact lens mounting on its circumference is advisable. An alternative method for fixing precision lenses is therefore desirable. This can be accomplished in two steps. As a first step, the lens must be gripped at its periphery so that none of the optically functional surfaces of the lens is compromised. However, the complete circumference has to be fixated gaplessly because a punctual fixation has the disadvantage of deforming the lens surface asymmetrically. As a second step, the freely hanging lens surface should be supported to minimize deformation. An approach had to be found that supports the surface like a solid bearing but at the same time does not touch it. Therefore, the usage of an incompressible fluid as a hydrostatic bearing for full-surface support is pursued. For this purpose, the bottom side of the lens has to be stored on water. The results of the FEM simulation showed that with a fluid bearing the resulting deformations can be drastically reduced in comparison to a freely hanging surface. Furthermore, under the right conditions, a resulting deformation comparable to a full surface solid support can be achieved. The content of this paper is a test series under laboratory conditions for a first validation of the theoretical results. Therefore, a prototype model to test a lens fixation with a fluid bearing was developed and manufactured. The resulting deformations were measured with an interferometer and the effects are discussed.

Proceedings Article | 15 June 2017 Paper

Analysis of the influence of the workpiece self-weight in precision optics manufacturing using FEM simulation

Christian Trum, Sebastian Sitzberger, Rolf Rascher

Proceedings Volume 10326, 103260O (2017) https://doi.org/10.1117/12.2273023

KEYWORDS: Optics manufacturing, Finite element methods, Precision optics, Optical simulations, Lens manufacturing, Polishing, Lenses

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Proceedings Article | 15 June 2017 Paper

Advanced method for the characterization of polishing suspensions

Christian Trum, Rolf Rascher, Sebastian Sitzberger

Proceedings Volume 10326, 103260I (2017) https://doi.org/10.1117/12.2272431

KEYWORDS: Polishing, Chemical mechanical planarization, Surface finishing, Glasses, Particles, Materials processing, Precision optics, Manufacturing, Foam, Magnesium

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Proceedings Article | 30 June 2016 Paper

Improving efficiency of chemo-mechanical polishing processes by systematic selection and conditioning of the polishing suspension

Christian Trum, Rolf Rascher

Proceedings Volume 10009, 1000902 (2016) https://doi.org/10.1117/12.2236000

KEYWORDS: Polishing, Chemical mechanical planarization, Optical design, Tolerancing, Glasses, Optics manufacturing, Environmental sensing, Surface finishing, Ion beams, Manufacturing

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Proceedings Article | 30 June 2016 Paper

Hexapod as primary kinematic system for applications in the optic industry

R. Schneider, C. Trum

Proceedings Volume 10009, 1000906 (2016) https://doi.org/10.1117/12.2235400

KEYWORDS: Optics manufacturing, Aspheric lenses, Kinematics, Raster graphics, Spherical lenses, Analytical research, Precision optics, Aspheric lenses, Kinematics, Microchannel plates, Manufacturing, Surface finishing

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Proceedings Article | 15 October 2013 Paper

Determination of a suitable parameter field for the active fluid jet polishing process

Roland Maurer, Christian Trum, Heiko Biskup, Rolf Rascher, Christine Wünsche

Proceedings Volume 8884, 888406 (2013) https://doi.org/10.1117/12.2028752

KEYWORDS: Polishing, Surface finishing, Software development, Neodymium, Magnetorheological finishing, Electronic filtering, Applied sciences, Distributed interactive simulations, Precision optics, Surface roughness

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Showing 5 of 11 publications

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