Mr. Johannes Liebl Profile

Johannes Liebl

Project Engineer at Technische Hochschule Deggendorf

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Publications (15)

Proceedings Article | 20 August 2020 Presentation + Paper

Interferometric measurement with robot kinematics

Simon Killinger, Johannes Liebl, Rolf Rascher

Proceedings Volume 11487, 114870I (2020) https://doi.org/10.1117/12.2568348

KEYWORDS: Interferometry, Kinematics, Process control, Precision optics, Optics manufacturing, Polishing, Control systems, Calibration, Interferometers, Mechanics

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Proceedings Article | 8 July 2020 Paper

First steps towards an automated polishing process chain using one robot

Simon Killinger, Johannes Liebl, Rolf Rascher

Proceedings Volume 11478, 114780I (2020) https://doi.org/10.1117/12.2564840

KEYWORDS: Interferometry, Kinematics, Optics manufacturing, Precision optics, Polishing, Actuators, Robotic systems, Interferometers, Optical components

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Proceedings Article | 8 July 2020 Paper

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

Sebastian Sitzberger, Johannes Liebl, Christian Trum, Rolf Rascher

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 | 28 June 2019 Paper

Zero-point clamping systems in optical production

Sebastian Sitzberger, Johannes Liebl, Jakob Reitberger, Rolf Rascher

Proceedings Volume 11171, 111710J (2019) https://doi.org/10.1117/12.2528774

KEYWORDS: Optics manufacturing, Manufacturing, Process control, Tolerancing, Interfaces, Reliability, Precision optics, Optical alignment, Metals, Mirrors

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Proceedings Article | 28 June 2019 Paper

Mid-spatial frequency errors in feed direction occurring in ADAPT polishing

S. Killinger, J. Liebl, R. Rascher

Proceedings Volume 11171, 111710G (2019) https://doi.org/10.1117/12.2528114

KEYWORDS: Polishing, Surface finishing, Spatial frequencies, Foam, Convolution, Aspheric lenses, Optics manufacturing, Precision optics, Superposition, Microchannel plates

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Proceedings Article | 18 August 2018 Paper

Model based error separation of power spectral density artefacts in wavefront measurement

Alexander Haberl, Antonia Harsch, Gerald Fütterer, Johannes Liebl, Christof Pruß, Rolf Rascher, Wolfgang Osten

Proceedings Volume 10749, 107490T (2018) https://doi.org/10.1117/12.2321106

KEYWORDS: Interferometers, Wavefronts, Calibration, Phase transfer function, Mirrors, Objectives, Phase measurement, Fizeau interferometers, Sensors, Modulation transfer functions

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Proceedings Article | 7 August 2018 Paper

Contribution of the phase transfer function of extended measurement cavities to mid spatial frequencies and the overall error budget

G. Fütterer, J. Liebl, A. Haberl

Proceedings Volume 10829, 108290L (2018) https://doi.org/10.1117/12.2318711

KEYWORDS: Spatial frequencies, Phase transfer function, Sensors, Mirrors, Modulation transfer functions, Fizeau interferometers, Interferometers, Phase measurement, Point spread functions, Stars

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A challenge of coaxial - measurement cavity based - interferometer is to realize an interference contrast in the vicinity of one and to realize a complete elimination of the parasitic reflections. Another challenge, which also exists in non-coaxial setups, is the phase transfer function of extended measurement cavities. Ideally, the surface under test (SUT) and the reference surface (REF) are both exactly imaged onto the detector plane. In practice, SUT and REF have to be placed within the depth of field (DOF), which refers to the object space. The term depth of focus refers to the image space. To avoid confusion, the depth of field might be referred to as DOOF (depth of object field) and the depth of focus might be referred to as DOIF (depth of image field).

However, in many measurement situations, the REF is not placed within the DOOF, which is the small z-range, which is imaged onto the detector plane. Furthermore, the phase transfer function (PTF) of the REF and the image distortion of the REF are both dependent on the focal plane used to image the SUT onto the detector plane. Effects as phase deformation, image distortion and image blurring have to be taken into account when using extended measurement cavities. This can be done by using a look up table (LUT), which contains simulated and/or calibrated data. Thus, the related system error can be subtracted. A remaining challenge is an unknown object under test (OUT), which is measured by using a double path arrangement. The measured wave front depends on the two surfaces of the OUT and the position of the return mirror. For simplicity, a homogeneous substrate and a perfect return mirror might be presumed. The simulation of waves propagating within extended measurement cavities, as well as measurement results, will be discussed. In addition, the influence on the power spectral density (PSD) will be described. This is important for high end correction techniques as e.g. magneto rheological figuring (MRF) and ion beam figuring (IBF).

Proceedings Article | 7 August 2018 Paper

DefGO

J. Liebl, C. Schopf, R. Rascher

Proceedings Volume 10829, 108290I (2018) https://doi.org/10.1117/12.2318704

KEYWORDS: Lenses, Coating, Manufacturing, Deflectometry, Optics manufacturing, Liquids, Glasses, Cameras, Reflection, Solids

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Proceedings Article | 7 August 2018 Paper

ABC-polishing

Alexander Haberl, Johannes Liebl, Rolf Rascher

Proceedings Volume 10829, 1082906 (2018) https://doi.org/10.1117/12.2318549

KEYWORDS: Polishing, Zernike polynomials, Tolerancing, Magnetorheological finishing, Databases, Spherical lenses, Surface finishing, Ion beams, Ion beam finishing, Manufacturing

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In the past, steadily increasing demands on the imaging properties of optics have led more and more precise spherical apertures. For a long time, these optical components have been produced in a satisfying quality using classic polishing methods such as pitch polishing. The advance of computer-controlled subaperture (SA) polishing techniques improved the accuracy of spheres. However, this new machine technology also made it possible to produce new lens geometries, such as aspheres.

In contrast to classic polishing methods, the high determinism of SA polishing allows a very specific correction of the surface defect. The methods of magneto-rheological finishing (MRF) [1], [2] and ion beam figuring (IBF) [3], [4] stand out in particular because of the achievable shape accuracy. However, this leads to the fact that a principle of manufacturing "As exact as possible, as precise as necessary" [5] is often ignored. The optical surfaces often produced with unnecessary precision, result at least in increased processing times.

The increasing interconnection of the production machines and the linking with databases already enables a consistent database to be established. It is possible to store measurements, process characteristics or tolerances for the individual production steps in a structured way. The difficulty, however, lies in the reasonable evaluation of the measurement data.

This is where this publication comes in. The smart evaluation of the measurement data with the widespread Zernike polynomials should result in a classification, depending on the required manufacturing tolerance. In combination with the so-called ABC analysis, all surface defects can be categorized. In this way, an analytic breakdown of a - initially confusing - overall problem is made. With the aid of cost functions [6] an evaluation and consequently a deduction of actions is made possible. Thus, for example, the isolated processing of rotationally symmetrical errors in spiral mode, setup times and machining times can be reduced while avoiding mid spatial frequency errors (MSFE) at the same time.

Proceedings Article | 16 October 2017 Paper

Cheap and fast measuring roughness on big surfaces with an imprint method

C. Schopf, J. Liebl, R. Rascher

Proceedings Volume 10448, 1044822 (2017) https://doi.org/10.1117/12.2279671

KEYWORDS: Surface finishing, Polishing, Optics manufacturing, Glasses, Interferometers, Metals, Manufacturing

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Proceedings Article | 30 June 2016 Paper

Deflectometric acquisition of large optical surfaces (DaOS) using a new physical measurement principle: vignetting field stop procedure

E. Hofbauer, R. Rascher, M. Schilke, J. Liebl, J.-P. Richters

Proceedings Volume 10009, 100090A (2016) https://doi.org/10.1117/12.2236134

KEYWORDS: Vignetting, Mirrors, Interferometry, Spherical lenses, Sensors, Autocollimators, Error analysis, Photovoltaics, Interferometers, Prisms

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Proceedings Article | 30 June 2016 Paper

Interferometric measurement of highly accurate flat surfaces

J. Liebl, H. Linthe, S. Sitzberger, R. Rascher

Proceedings Volume 10009, 100090X (2016) https://doi.org/10.1117/12.2235525

KEYWORDS: Optics manufacturing, Interferometry, Precision optics, Measurement devices, Interferometers, Testing and analysis, Metrology, Kinematics, Wavefronts, Optical testing

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Proceedings Article | 30 June 2016 Paper

Surface reconstruction by using Zernike polynomials

Manon Schilke, Johannes Liebl, Christine Wünsche

Proceedings Volume 10009, 1000910 (2016) https://doi.org/10.1117/12.2236305

KEYWORDS: Zernike polynomials, Autocollimators, Deflectometry, Plano, Algorithm development, Interferometry, Optical testing, Data conversion, Reconstruction algorithms, Wavefronts

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Proceedings Article | 11 October 2015 Paper

The manufacturing and metrology of off-axis mirrors

Karlheinz Penzkofer, Rolf Rascher, Lutz Küpper, Johannes Liebl

Proceedings Volume 9633, 96330X (2015) https://doi.org/10.1117/12.2195893

KEYWORDS: Optics manufacturing, Mirrors, Off axis mirrors, Surface finishing, Polishing, Manufacturing, Photovoltaics, Metrology, Interferometers, Telescopes

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Proceedings Article | 13 May 2013 Paper

Approach to the measurement of astronomical mirrors with new procedures

E. Hofbauer, R. Rascher, Th. Stubenrauch, J. Liebl, R. Maurer, A. Zimmermann, O. Rösch, J. Reitberger

Proceedings Volume 8788, 87881D (2013) https://doi.org/10.1117/12.2020414

KEYWORDS: Interferometry, Photovoltaics, Sensors, Mirrors, Deflectometry, Error analysis, Spherical lenses, Cameras, Interferometers, Astronomy

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Showing 5 of 15 publications

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