Alexander Haberl, M.Sc.

Operative Management

COO


Bürozeiten

Monday - Thursday / Technology Campus Teisnach T002 / 07:00 - 16:00 Friday / Faculty NuW L002 / 07:00 - 13:00


Lecture
  • Simon Killinger
  • Alexander Haberl
  • Rolf Rascher
Analysis of residual errors during computer controlled polishing
  • 2019
In computer controlled subapertur polishing the formation of mid spatial frequency errors (MSFE) needs special attention. In this work the formation of MSFE in feed direction is investigated using the ADAPT tool from Satisloh.
Lecture
  • Simon Killinger
  • Alexander Haberl
  • Rolf Rascher
Analysis of residual errors during computer controlled polishing
  • 2019
In computer controlled subapertur polishing the formation of mid spatial frequency errors (MSFE) needs special attention. In this work the formation of MSFE in feed direction is investigated using the ADAPT tool from Satisloh.
Contribution
  • 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
  • 2018

DOI: 10.1117/12.2321106

Contribution
  • A. Harsch
  • C. Pruss
  • Alexander Haberl
  • W. Osten
Tilted wave interferometry for testing large surfaces
  • 2018

DOI: 10.1117/12.2318573

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.
Contribution
  • 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
  • 2018

DOI: 10.1117/12.2318711

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).
Contribution
  • 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
  • 2018

DOI: 10.1117/12.2321106

Lecture
  • 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
  • 2018
Contribution
  • A. Harsch
  • C. Pruss
  • Alexander Haberl
  • W. Osten
Tilted wave interferometry for testing large surfaces
  • 2018

DOI: 10.1117/12.2318573

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.
Contribution
  • 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
  • 2018

DOI: 10.1117/12.2318711

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).
Contribution
  • Alexander Haberl
  • Johannes Liebl
  • Rolf Rascher
ABC-polishing
  • 2018

DOI: 10.1117/12.2318549

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.
Lecture
  • 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
  • 2018
Contribution
  • Alexander Haberl
  • Johannes Liebl
  • Rolf Rascher
ABC-polishing
  • 2018

DOI: 10.1117/12.2318549

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.
Contribution
  • Robert Schneider
  • Alexander Haberl
  • Rolf Rascher
Polishing tool and the resulting TIF for three variable machine parameters as input for the removal simulation
  • 2017

DOI: 10.1117/12.2267415

Lecture
  • 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
  • 2017
Contribution
  • Alexander Haberl
  • Rolf Rascher
Yet one more dwell time algorithm
  • 2017

DOI: 10.1117/12.2270540

Contribution
  • Robert Schneider
  • Alexander Haberl
  • Rolf Rascher
Polishing tool and the resulting TIF for three variable machine parameters as input for the removal simulation
  • 2017

DOI: 10.1117/12.2267415

Contribution
  • Robert Schneider
  • Alexander Haberl
  • Rolf Rascher
Parametrization of a Subaperture Polishing Tool - Analysis of the Path Tests , volPaper OM3B.2
  • 2017
Contribution
  • Robert Schneider
  • Alexander Haberl
  • Rolf Rascher
Parametrization of a Subaperture Polishing Tool - Analysis of the Path Tests , volPaper OM3B.2
  • 2017
Lecture
  • 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
  • 2017
Contribution
  • Alexander Haberl
  • Rolf Rascher
Yet one more dwell time algorithm
  • 2017

DOI: 10.1117/12.2270540

Contribution
  • Heiko Biskup
  • Alexander Haberl
  • Rolf Rascher
Surface errors in the course of machining precision optics
  • 2015

DOI: 10.1117/12.2189991

Precision optical components are usually machined by grinding and polishing in several steps with increasing accuracy. Spherical surfaces will be finished in a last step with large tools to smooth the surface. The requested surface accuracy of non-spherical surfaces only can be achieved with tools in point contact to the surface. So called mid-frequency errors (MSFE) can accumulate with zonal processes. This work is on the formation of surface errors from grinding to polishing by conducting an analysis of the surfaces in their machining steps by non-contact interferometric methods. The errors on the surface can be distinguished as described in DIN 4760 whereby 2nd to 3rd order errors are the so-called MSFE. By appropriate filtering of the measured data frequencies of errors can be suppressed in a manner that only defined spatial frequencies will be shown in the surface plot. It can be observed that some frequencies already may be formed in the early machining steps like grinding and main-polishing. Additionally it is known that MSFE can be produced by the process itself and other side effects. Beside a description of surface errors based on the limits of measurement technologies, different formation mechanisms for selected spatial frequencies are presented. A correction may be only possible by tools that have a lateral size below the wavelength of the error structure. The presented considerations may be used to develop proposals to handle surface errors. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Contribution
  • Heiko Biskup
  • Alexander Haberl
  • Rolf Rascher
Surface errors in the course of machining precision optics
  • 2015

DOI: 10.1117/12.2189991

Precision optical components are usually machined by grinding and polishing in several steps with increasing accuracy. Spherical surfaces will be finished in a last step with large tools to smooth the surface. The requested surface accuracy of non-spherical surfaces only can be achieved with tools in point contact to the surface. So called mid-frequency errors (MSFE) can accumulate with zonal processes. This work is on the formation of surface errors from grinding to polishing by conducting an analysis of the surfaces in their machining steps by non-contact interferometric methods. The errors on the surface can be distinguished as described in DIN 4760 whereby 2nd to 3rd order errors are the so-called MSFE. By appropriate filtering of the measured data frequencies of errors can be suppressed in a manner that only defined spatial frequencies will be shown in the surface plot. It can be observed that some frequencies already may be formed in the early machining steps like grinding and main-polishing. Additionally it is known that MSFE can be produced by the process itself and other side effects. Beside a description of surface errors based on the limits of measurement technologies, different formation mechanisms for selected spatial frequencies are presented. A correction may be only possible by tools that have a lateral size below the wavelength of the error structure. The presented considerations may be used to develop proposals to handle surface errors. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.