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Hällstig, Emil
Publications (10 of 14) Show all publications
Khodadad, D., Bergström, P., Hällstig, E. & Sjödahl, M. (2015). Fast and robust automatic calibration for single-shot dual-wavelength digital holography based on speckle displacements (ed.). Paper presented at . Applied Optics, 54(16), 5003-5010
Open this publication in new window or tab >>Fast and robust automatic calibration for single-shot dual-wavelength digital holography based on speckle displacements
2015 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 54, no 16, p. 5003-5010Article in journal (Refereed) Published
Abstract [en]

The objective of this paper is to describe a fast and robust automatic single-shot dual-wavelength holographic calibration method that can be used for online shape measurement applications. We present a model of the correction in two terms for each lobe, one to compensate the systematic errors caused by off-axis angles and the other for the curvature of the reference waves, respectively. Each hologram is calibrated independently without a need for an iterative procedure or information of the experimental set-up. The calibration parameters are extracted directly from speckle displacements between different reconstruction planes. The parameters can be defined as any fraction of a pixel to avoid the effect of quantization. Using the speckle displacements, problems associated with phase wrapping is avoided. The procedure is shown to give a shape accuracy of 34 μm using a synthetic wavelength of 1.1 mm for a measurement on a cylindrical test object with a trace over a field of view of 18  mm×18  mm.

Keywords
digital holography, Speckle imaging, Interferometry, metrology, calibration, surface measurement, multiplexing, single shot, Technology - Engineering physics, Teknikvetenskap - Teknisk fysik
National Category
Applied Mechanics Computational Mathematics
Research subject
Experimental Mechanics; Scientific Computing
Identifiers
urn:nbn:se:ltu:diva-10347 (URN)10.1364/AO.54.005003 (DOI)000355555700009 ()2-s2.0-84942372341 (Scopus ID)924b8540-da35-4fa3-90a0-89f1ac2a9d3d (Local ID)924b8540-da35-4fa3-90a0-89f1ac2a9d3d (Archive number)924b8540-da35-4fa3-90a0-89f1ac2a9d3d (OAI)
Note
Validerad; 2015; Nivå 2; 20150522 (davkho)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Khodadad, D., Amer, E., Gren, P., Melander, E., Hällstig, E. & Sjödahl, M. (2015). Single-shot dual-polarization holography: measurement of the polarization state of a magnetic sample (ed.). In: (Ed.), Fernando Mendoza Santoyo; Eugenio R. Mendez (Ed.), SPECKLE 2015: VI International Conference on Speckle Metrology. : SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Single-shot dual-polarization holography: measurement of the polarization state of a magnetic sample
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2015 (English)In: SPECKLE 2015: VI International Conference on Speckle Metrology / [ed] Fernando Mendoza Santoyo; Eugenio R. Mendez, SPIE - International Society for Optical Engineering, 2015Conference paper, Published paper (Refereed)
Abstract [en]

In this paper a single-shot digital holographic set-up with two orthogonally polarized reference beams is proposed to achieve rapid acquisition of Magneto-Optical Kerr Effect images. Principles of the method and the background theory for dynamic state of polarization measurement by use of digital holography are presented. This system has no mechanically moving elements or active elements for polarization control and modulation. An object beam is combined with two reference beams at different off-axis angles and is guided to a detector. Then two complex fields (interference terms) representing two orthogonal polarizations are recorded in a single frame simultaneously. Thereafter the complex fields are numerically reconstructed and carrier frequency calibration is done to remove aberrations introduced in multiplexed digital holographic recordings. From the numerical values of amplitude and phase, a real time quantitative analysis of the polarization state is possible by use of Jones vectors. The technique is demonstrated on a magnetic sample that is a lithographically patterned magnetic microstructure consisting of thin permalloy parallel stripes

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2015
Series
Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X ; 9660
Keywords
Single-shot acquisition, holography, dual-polarization, Magneto-Optical Kerr Effect, polarization, measurement, multiplexed holography, Technology - Electrical engineering, electronics and photonics, Teknikvetenskap - Elektroteknik, elektronik och fotonik
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-34046 (URN)10.1117/12.2189782 (DOI)000360300500036 ()2-s2.0-84943551779 (Scopus ID)82680dae-42a6-4c75-92d6-621694a624d6 (Local ID)9781628418781 (ISBN)82680dae-42a6-4c75-92d6-621694a624d6 (Archive number)82680dae-42a6-4c75-92d6-621694a624d6 (OAI)
Note
Validerad; 2015; Nivå 1; 20150829 (davkho)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Khodadad, D., Bergström, P., Hällstig, E. & Sjödahl, M. (2014). Dual-wavelength digital holography: single shot calibration (ed.). In: (Ed.), (Ed.), Interferometry XVII: Techniques and Analysis. Paper presented at Interferometry XVII : Techniques and Analysis 17/08/2014 - 21/08/2014. Bellingham, Wash: SPIE - International Society for Optical Engineering, Article ID 920305.
Open this publication in new window or tab >>Dual-wavelength digital holography: single shot calibration
2014 (English)In: Interferometry XVII: Techniques and Analysis, Bellingham, Wash: SPIE - International Society for Optical Engineering, 2014, article id 920305Conference paper, Published paper (Refereed)
Abstract [en]

In an on line shape measurement in disturbed environment, use of many wavelengths in order to avoid phase ambiguity may become a problem as it is necessary to acquire all holograms simultaneously due to environmental disturbances. Therefore to make the shape data available the different holograms have to be extracted from a single recorded image in spectral domain. Appropriate cut areas in the Fourier method are therefore of great importance for decoding information carried by different wavelengths. Furthermore using different laser sources, induces aberration and pseudo phase changes which must be compensated. To insure any phase change is only because of the object shape, calibration is therefore indispensable. For this purpose, effects of uncontrolled carrier frequency filtering are discussed. A registration procedure is applied using minimum speckle displacements to find the best cut area to extract and match the interference terms. Both holograms are numerically propagated to a focus plane to avoid any unknown errors. Deviations between a reference known plate and its measurement are found and used for calibration. We demonstrate that phase maps and speckle displacements can be recovered free of chromatic aberrations. To our knowledge, this is the first time that a single shot dual wavelength calibration is reported by defining a criteria to make the spatial filtering automatic avoiding the problems of manual methods. The procedure is shown to give shape accuracy of 35μm with negligible systematic errors using a synthetic wavelength of 1.1 mm.

Place, publisher, year, edition, pages
Bellingham, Wash: SPIE - International Society for Optical Engineering, 2014
Series
Proceedings of S P I E - International Society for Optical Engineering, ISSN 0277-786X ; 9203
Keywords
digital holography, dual-wavelength, single shot, calibration, speckle displacements, on line shape measurement, image correlation, Technology - Engineering physics, Teknikvetenskap - Teknisk fysik
National Category
Applied Mechanics Computational Mathematics
Research subject
Experimental Mechanics; Scientific Computing
Identifiers
urn:nbn:se:ltu:diva-39188 (URN)10.1117/12.2062101 (DOI)000354364200005 ()2-s2.0-84922880623 (Scopus ID)dd50de19-cde8-41f8-bbb9-c54962ee2580 (Local ID)9781628412314 (ISBN)dd50de19-cde8-41f8-bbb9-c54962ee2580 (Archive number)dd50de19-cde8-41f8-bbb9-c54962ee2580 (OAI)
Conference
Interferometry XVII : Techniques and Analysis 17/08/2014 - 21/08/2014
Note
Godkänd; 2014; 20140827 (davkho)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-07-10Bibliographically approved
Bergström, P., Khodadad, D., Hällstig, E. & Sjödahl, M. (2014). Dual-wavelength digital holography: single-shot shape evaluation using speckle displacements and regularization (ed.). Paper presented at . Applied Optics, 53(1), 123-131
Open this publication in new window or tab >>Dual-wavelength digital holography: single-shot shape evaluation using speckle displacements and regularization
2014 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 53, no 1, p. 123-131Article in journal (Refereed) Published
National Category
Computational Mathematics Applied Mechanics
Research subject
Scientific Computing; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-13247 (URN)10.1364/AO.53.000123 (DOI)000329034300018 ()2-s2.0-84891611011 (Scopus ID)c7007a95-2668-4842-9dbb-89edbe94a0fa (Local ID)c7007a95-2668-4842-9dbb-89edbe94a0fa (Archive number)c7007a95-2668-4842-9dbb-89edbe94a0fa (OAI)
Note
Validerad; 2014; 20131210 (berper)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Khodadad, D., Bergström, P., Hällstig, E. & Sjödahl, M. (2014). Single Shot Dual-Wavelength Digital Holography: Calibration Based on Speckle Displacements (ed.). International Journal of Optomechatronics, 8(4), 326-339
Open this publication in new window or tab >>Single Shot Dual-Wavelength Digital Holography: Calibration Based on Speckle Displacements
2014 (English)In: International Journal of Optomechatronics, ISSN 1559-9612, Vol. 8, no 4, p. 326-339Article in journal (Refereed) Published
Abstract [en]

We present a calibration method which allows single shot dual wavelength online shape measurement in a disturbed environment. Effects of uncontrolled carrier frequency filtering are discussed as well. We demonstrate that phase maps and speckle displacements can be recovered free of chromatic aberrations. To our knowledge, this is the first time that a single shot dual wavelength calibration is reported by defining a criteria to make the spatial filtering automatic avoiding the problems of manual methods. The procedure is shown to give shape accuracy of 35 µm with negligible systematic errors using a synthetic wavelength of 1.1 mm.

National Category
Applied Mechanics Computational Mathematics
Research subject
Experimental Mechanics; Scientific Computing
Identifiers
urn:nbn:se:ltu:diva-3966 (URN)10.1080/15599612.2014.942932 (DOI)000343656700010 ()2-s2.0-84908215753 (Scopus ID)1d0489e0-ecaf-433b-911f-feff8edfa5db (Local ID)1d0489e0-ecaf-433b-911f-feff8edfa5db (Archive number)1d0489e0-ecaf-433b-911f-feff8edfa5db (OAI)
Note

Validerad; 2014; Bibliografisk uppgift: Special Issue: Advances in Optical Imaging and Metrology - Selected papers from the conference Fringe 2013; 20140815 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-08-16Bibliographically approved
Bergström, P., Khodadad, D., Hällstig, E. & Sjödahl, M. (2014). Single shot shape evaluation using dual-wavelength holographic reconstructions and regularization (ed.). In: (Ed.), Wolfgang Osten (Ed.), Fringe 2013: 7th International Workshop on Advanced Optical Imaging and Metrology (pp. 103-108). Berlin: Encyclopedia of Global Archaeology/Springer Verlag
Open this publication in new window or tab >>Single shot shape evaluation using dual-wavelength holographic reconstructions and regularization
2014 (English)In: Fringe 2013: 7th International Workshop on Advanced Optical Imaging and Metrology / [ed] Wolfgang Osten, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 103-108Conference paper, Published paper (Refereed)
Abstract [en]

The aim of this work is to evaluate the shape of a free form object using single shot digital holography. The digital holography results in a gradient field and wrapped phase maps representing the shape of the object. The task is then to find a surface representation from this data which is an inverse problem. To solve this inverse problem we are using regularization with additional shape information from the CAD-model of the measured object.

Place, publisher, year, edition, pages
Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2014
National Category
Computational Mathematics Applied Mechanics
Research subject
Scientific Computing; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-36941 (URN)10.1007/978-3-642-36359-7_12 (DOI)84903961751 (Scopus ID)ac6d1b08-3fec-4d85-a871-f8286d046e72 (Local ID)978-3-642-36358-0 (ISBN)978-3-642-36359-7 (ISBN)ac6d1b08-3fec-4d85-a871-f8286d046e72 (Archive number)ac6d1b08-3fec-4d85-a871-f8286d046e72 (OAI)
Note
Godkänd; 2014; 20130913 (berper)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Khodadad, D., Hällstig, E. & Sjödahl, M. (2013). Dual-wavelength digital holographic shape measurement using speckle movements and phase gradients (ed.). Paper presented at . Optical Engineering: The Journal of SPIE, 52(10), Article ID 101912.
Open this publication in new window or tab >>Dual-wavelength digital holographic shape measurement using speckle movements and phase gradients
2013 (English)In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 52, no 10, article id 101912Article in journal (Refereed) Published
Abstract [en]

A new method to measure shape by analyzing the speckle movements in images generated by numerical propagation from dual-wavelength holograms is presented. The relationship of the speckle movements at different focal distances is formulated, and it is shown how this carries information about the surface position as well as the local slope of the object. It is experimentally verified that dual-wavelength holography and numerically generated speckle images can be used together with digital speckle correlation to retrieve the object shape. From a measurement on a cylindrical test object, the method is demonstrated to have a random error in the order of a few micrometers.

Keywords
digital holography, speckle movements, shape measurement, dual wavelength, phase gradients, Technology - Electrical engineering, electronics and photonics, Teknikvetenskap - Elektroteknik, elektronik och fotonik
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-16110 (URN)10.1117/1.OE.52.10.101912 (DOI)000328254600017 ()2-s2.0-84886787525 (Scopus ID)fb060241-0d1c-469d-a1ab-a677c2bd2d18 (Local ID)fb060241-0d1c-469d-a1ab-a677c2bd2d18 (Archive number)fb060241-0d1c-469d-a1ab-a677c2bd2d18 (OAI)
Note
Validerad; 2013; 20130916 (davkho)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Khodadad, D., Sjödahl, M. & Hällstig, E. (2013). Shape reconstruction using dual wavelength digital holography and speckle movements (ed.). In: (Ed.), Peter H. Lehmann; Wolfgang Osten; Armando Albertazzi (Ed.), Optical Measurement Systems for Industrial Inspection VIII,: . Paper presented at Optical Measurement Systems for Industrial Inspection : 13/05/2013 - 13/05/2013. : SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Shape reconstruction using dual wavelength digital holography and speckle movements
2013 (English)In: Optical Measurement Systems for Industrial Inspection VIII, / [ed] Peter H. Lehmann; Wolfgang Osten; Armando Albertazzi, SPIE - International Society for Optical Engineering, 2013Conference paper, Published paper (Refereed)
Abstract [en]

A new technique to measure depth based on dual wavelength digital holography and image correlation of speckle movements is demonstrated. By numerical refocusing of the complex optical field to different focus planes and by measuring the speckle movements caused by a wavelength shift both the object surface position and its local slope can be determined. It is shown how the speckle movement varies linearly with the surface slope, the wavelength shift and the distance of the numerical propagation. This gives a possibility to measure the slope with approximately the same precision as from the interferometric phase maps. In addition, when the object surface is in focus there is no speckle movement so by estimating in what plane the speckle movement is zero the absolute surface position can be measured.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2013
Series
Proceedings of S P I E - International Society for Optical Engineering, ISSN 0277-786X ; 8788
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-39878 (URN)10.1117/12.2020471 (DOI)000323493700015 ()2-s2.0-84880718852 (Scopus ID)ecbd8f00-95cd-4b67-9fe7-51df416da530 (Local ID)978-0-8194-9604-1 (ISBN)ecbd8f00-95cd-4b67-9fe7-51df416da530 (Archive number)ecbd8f00-95cd-4b67-9fe7-51df416da530 (OAI)
Conference
Optical Measurement Systems for Industrial Inspection : 13/05/2013 - 13/05/2013
Note
Validerad; 2013; Bibliografisk uppgift: Article number 87880I; 20130814 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-07-10Bibliographically approved
Rosendahl, S., Hällstig, E., Gren, P. & Sjödahl, M. (2010). Phase errors due to speckles in laser fringe projection (ed.). Paper presented at . Applied Optics, 49(11), 2047-2053
Open this publication in new window or tab >>Phase errors due to speckles in laser fringe projection
2010 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 49, no 11, p. 2047-2053Article in journal (Refereed) Published
Abstract [en]

When measuring a three-dimensional shape with triangulation and projected interference fringes it is of interest to reduce speckle contrast without destroying the coherence of the projected light. A moving aperture is used to suppress the speckles and thereby reduce the phase error in the fringe image. It is shown that the phase error depends linearly on the ratio between the speckle contrast and the modulation of the fringes. In this investigation the spatial carrier method was used to extract the phase, where the phase error also depends on filtering the Fourier spectrum. An analytical expression for the phase error is derived. Both the speckle reduction and the theoretical expressions for the phase error are verified by simulations and experiments. It was concluded that a movement of the aperture by three aperture diameters during exposure of the image reduces the speckle contrast and hence the phase error by 60%. In the experiments, a phase error of 0.2 rad was obtained.

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-4951 (URN)10.1364/AO.49.002047 (DOI)000276612200007 ()20390003 (PubMedID)2f52d150-3d57-11df-a0f4-000ea68e967b (Local ID)2f52d150-3d57-11df-a0f4-000ea68e967b (Archive number)2f52d150-3d57-11df-a0f4-000ea68e967b (OAI)
Note
Validerad; 2010; 20100401 (sarros)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Rosendahl, S., Hällstig, E., Gren, P. & Sjödahl, M. (2010). Phase errors in speckle reduced laser fringe projection (ed.). In: (Ed.), Armando Albertazzi Gonçalves (Ed.), Speckle 2010: optical metrology : 13 - 15 September 2010, Florianópolis, Brazil. Paper presented at International Conference on Correlation Optics : 13/09/2010 - 15/10/2010 (pp. 73871E). Bellingham, Wash: SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Phase errors in speckle reduced laser fringe projection
2010 (English)In: Speckle 2010: optical metrology : 13 - 15 September 2010, Florianópolis, Brazil / [ed] Armando Albertazzi Gonçalves, Bellingham, Wash: SPIE - International Society for Optical Engineering, 2010, p. 73871E-Conference paper, Published paper (Refereed)
Abstract [en]

When measuring 3D-shape with triangulation and projected interference fringes it is of interest to reduce the phase error in the fringe pattern. A study has been carried out concerning parameters that will affect the phase error and an analytical expression has been derived. It is concluded that the phase error depends on the speckle contrast, C, and the modulation, M, of the fringes and since the phase in this investigation is determined using the spatial carrier method the phase error also depends on the filtering of the Fourier spectrum. To reduce the phase error this work has been focusing on suppressing the speckle contrast. For this the method with a moving aperture is used; a disk with several apertures is rotated in the aperture plane of the camera lens. To verify the derived expression for the phase error and the method to suppress speckles both numerical simulations and experiments have been performed. In the measurements made it was concluded that after an aperture movement of three aperture diameters the speckle contrast and hence the phase error was reduced by 60 %. A phase error of 0.15 radians was obtained in the experiments, thus approximately 1/40 of a fringe period

Place, publisher, year, edition, pages
Bellingham, Wash: SPIE - International Society for Optical Engineering, 2010
Series
Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X ; 7387
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-28482 (URN)10.1117/12.869659 (DOI)000287657900050 ()2-s2.0-78049385535 (Scopus ID)24c9ee40-f08e-11df-8b36-000ea68e967b (Local ID)978-0-8194-7670-8 (ISBN)24c9ee40-f08e-11df-8b36-000ea68e967b (Archive number)24c9ee40-f08e-11df-8b36-000ea68e967b (OAI)
Conference
International Conference on Correlation Optics : 13/09/2010 - 15/10/2010
Note
Validerad; 2010; 20101115 (andbra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
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