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Alexander Haberl, M.Sc.

Fakultät Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Mitarbeiter:innen

Operative Leitung

T 102

09923/80108-423

Sortierung:
Beitrag (Sammelband oder Tagungsband)

  • Alexander Haberl
  • Johannes Liebl
  • Rolf Rascher

ABC-polishing

pg. 1082906.

  • (2018)

DOI: 10.1117/12.2318549

Abstract anzeigen

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.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • TC Teisnach Optik
  • NACHHALTIG
Beitrag (Sammelband oder Tagungsband)

  • A. Harsch
  • C. Pruss
  • Alexander Haberl
  • W. Osten

Tilted wave interferometry for testing large surfaces

pg. 1082908.

  • (2018)

DOI: 10.1117/12.2318573

Abstract anzeigen

Measuring large surfaces interferometrically is a straight forward established technology, as long as they are concave and spherical. The situation chnages completely if aspheres and freeforms have to be measured. The application of a Tilted Wave Interferometer opens up possibilities to measure large concave surfaces of any shape without compensation optics. For the investigation of large convex aspheres, it is necessary to make use of stitching methods. Due to the freeform capability of the Tilted Wave Interefrometer, it is possible to acquire larger subapertures compared to null interferometers. Therefore measurement and computation time are reduced.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • NACHHALTIG
Vortrag

  • Alexander Haberl
  • H. Harsch
  • Gerald Fütterer
  • Johannes Liebl
  • C. Pruß
  • Rolf Rascher
  • W. Osten

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

In: SPIE Optical Engineering + Applications Conference on Interferometry XIX

San Diego, CA, USA

  • 19.-23.08.2018 (2018)
  • TC Teisnach Optik
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
  • NACHHALTIG
Beitrag (Sammelband oder Tagungsband)

  • Alexander Haberl
  • H. Harsch
  • Gerald Fütterer
  • Johannes Liebl
  • C. Pruß
  • Rolf Rascher
  • W. Osten

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

pg. 107490T.

  • (2018)

DOI: 10.1117/12.2321106

  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • TC Teisnach Optik
  • NACHHALTIG
Beitrag (Sammelband oder Tagungsband)

  • Gerald Fütterer
  • Johannes Liebl
  • Alexander Haberl

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

pg. 108290L.

  • (2018)

DOI: 10.1117/12.2318711

Abstract anzeigen

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).
  • TC Teisnach Optik
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • NACHHALTIG
Beitrag (Sammelband oder Tagungsband)

  • Robert Schneider
  • Alexander Haberl
  • Rolf Rascher

Polishing tool and the resulting TIF for three variable machine parameters as input for the removal simulation

pg. 1032602.

  • (2017)

DOI: 10.1117/12.2267415

  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • TC Teisnach Optik
  • NACHHALTIG