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Publications (10 of 150) Show all publications
Wahl, J., Gren, P., Bergström, P., Lindbäck, T., Magnusson, M., Domeij, K. & Sjödahl, M. (2018). Comparison between process simulation and deformation measured by defocused speckle photography. In: M. Kujawińska ; L. R. Jaroszewicz (Ed.), Speckle 2018: VII International Conference On Speckle Metrology. Paper presented at SPECKLE 2018: VII International Conference on Speckle Metrology, 9-12 September 2018, Janów Podlaski, Poland.. SPIE - International Society for Optical Engineering, 10834, Article ID 108341K.
Open this publication in new window or tab >>Comparison between process simulation and deformation measured by defocused speckle photography
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2018 (English)In: Speckle 2018: VII International Conference On Speckle Metrology / [ed] M. Kujawińska ; L. R. Jaroszewicz, SPIE - International Society for Optical Engineering, 2018, Vol. 10834, article id 108341KConference paper, Published paper (Refereed)
Abstract [en]

Defocused laser speckle photography is used as a tool to measure the heat responses in a titanium component during laser heating. The evolution of the response is compared with a set of preprocessed Finite Element Simulations of the corresponding process with the aim to verify the simulation model and to find the simulation settings that best resemble the experimental results. The titanium component consists of a 300 x 100 mm2 substrate of thickness 3.2 mm on which a 200 x 30 x 11 mm3 ridge is built up using the laser metal deposition by wire process. The component is heated on the top of the ridge by a 300 W laser for 10 s and the deformation of the subtrate is followed throughout the heating-cooling cycle. The simulated deformation gradient is shown to resemble the measured response, and the magnitude of the response indicates that about 70 % of the laser power transferres into heat in the metal.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Series
Proceedings of SPIE - the International Society for Optical Engineering, ISSN 0277-786X ; 10834
Keywords
Laser speckle, deformation, in-process measurement
National Category
Applied Mechanics Other Mechanical Engineering
Research subject
Experimental Mechanics; Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-71895 (URN)10.1117/12.2319384 (DOI)000455052600052 ()2-s2.0-85058383509 (Scopus ID)9781510622975 (ISBN)
Conference
SPECKLE 2018: VII International Conference on Speckle Metrology, 9-12 September 2018, Janów Podlaski, Poland.
Funder
VINNOVA
Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2019-01-28Bibliographically approved
Amer, E., Gren, P., Ramser, K. & Sjödahl, M. (2018). Measurement of selective species concentration using spectroscopic holography. In: M. Kujawińska ; L. R. Jaroszewicz (Ed.), Speckle 2018: VII International Conference on Speckle Metrology. Paper presented at Speckle 2018: VII International Conference On Speckle Metrology 9-12 September 2018 Janów Podlaski, Poland. SPIE - International Society for Optical Engineering, 10834, Article ID 108340P.
Open this publication in new window or tab >>Measurement of selective species concentration using spectroscopic holography
2018 (English)In: Speckle 2018: VII International Conference on Speckle Metrology / [ed] M. Kujawińska ; L. R. Jaroszewicz, SPIE - International Society for Optical Engineering, 2018, Vol. 10834, article id 108340PConference paper, Published paper (Refereed)
Abstract [en]

Spectroscopic holography refers to techniques in which the detected hologram contains information about specific species in the medium under study. In general, at least two lasers are required with wavelengths chosen carefully to fit the interaction process utilized. In this process, energy from the shorter wavelength laser beam is transferred to the longer wavelength coherently through the process of stimulated emission. Two interaction mechanisms are considered; Stimulated Laser Induced Fluorescence (LIF) and Stimulated Raman Scattering (SRS), which both are species specific with the ability of coherent interaction. In this paper, the fundamental properties of spectroscopic holography is presented and demonstrated with a few idealized experiments. These validation experiments are performed in a gas chamber in which different gases may be blended and the gas pressure changed between 1-12 bars. In addition, two examples of applications are presented. In the first set of experiments, LIF holography is used to image light absorption and laser heating in a dye simultaneously. The second set of experiments is performed in a ow of methane gas. It is demonstrated that the combination of holographic phase measurements and SRS gain images may be used for calibration. This calibration may further be used to measure absolute concentration in a burning flame.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Series
Proceedings of SPIE - the International Society for Optical Engineering, ISSN 0277-786X ; 10834
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-72430 (URN)10.1117/12.2319386 (DOI)000455052600021 ()2-s2.0-85058412906 (Scopus ID)9781510622975 (ISBN)
Conference
Speckle 2018: VII International Conference On Speckle Metrology 9-12 September 2018 Janów Podlaski, Poland
Available from: 2019-01-03 Created: 2019-01-03 Last updated: 2019-01-28Bibliographically approved
Dittes, N., Pettersson, A., Sjödahl, M., Casselgren, J., Marklund, P. & Lugt, P. M. (2018). Optical Attenuation Characterization of Water Contaminated Lubricating Grease. Tribology Transactions, 61(4), 726-732
Open this publication in new window or tab >>Optical Attenuation Characterization of Water Contaminated Lubricating Grease
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2018 (English)In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 61, no 4, p. 726-732Article in journal (Refereed) Published
Abstract [en]

Water-contaminated grease samples are investigated with attenuation spectra in the visible and near-infrared (NIR) regions in this article. The purpose of this investigation was to identify a model with optical attenuation spectra such that the water content of grease samples could be characterized with a simple measurement setup using common methodology from the field of instrumental chemistry. The ratio between two chosen wavelengths of light appears to approximate the water content of grease samples with an acceptable coefficient of determination using a methodology to show what can potentially be done to develop condition monitoring tools. To illustrate the outlined method, a prestudy of grease aging and oxidation levels is also investigated to show that other variables do not significantly change the measurement.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Applied Mechanics
Research subject
Machine Elements; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-67205 (URN)10.1080/10402004.2017.1404175 (DOI)000438157400015 ()2-s2.0-85044094152 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-09 (rokbeg)

Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2018-12-14Bibliographically approved
Sjödahl, M. & Amer, E. (2018). Quantitative measurement of thin phase objects: comparison of speckle deflectometry and defocus-variant lateral shear interferometry. Applied Optics, 57(14), 3645-3652
Open this publication in new window or tab >>Quantitative measurement of thin phase objects: comparison of speckle deflectometry and defocus-variant lateral shear interferometry
2018 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 57, no 14, p. 3645-3652Article in journal (Refereed) Published
Abstract [en]

The two techniques of lateral shear interferometry and speckle deflectometry are analyzed in a common optical system for their ability to measure phase gradient fields of a thin phase object. The optical system is designed to introduce a shear in the frequency domain of a telecentric imaging system that gives a sensitivity of both techniques in proportion to the defocus introduced. In this implementation, both techniques successfully measure the horizontal component of the phase gradient field. The response of both techniques scales linearly with the defocus distance, and the precision is comparative, with a random error in the order of a few rad/mm. It is further concluded that the precision of the two techniques relates to the transverse speckle size in opposite ways. While a large spatial coherence width, and correspondingly a large lateral speckle size, makes lateral shear interferometry less susceptible to defocus, a large lateral speckle size is detrimental for speckle correlation. The susceptibility for the magnitude of the defocus is larger for the lateral shear interferometry technique as compared to the speckle deflectometry technique. The two techniques provide the same type of information; however, there are a few fundamental differences. Lateral shear interferometry relies on a special hardware configuration in which the shear angle is intrinsically integrated into the system. The design of a system sensitive to both in-plane phase gradient components requires a more complex configuration and is not considered in this paper. Speckle deflectometry, on the other hand, requires no special hardware, and both components of the phase gradient field are given directly from the measured speckle deformation field.

Place, publisher, year, edition, pages
Optical Society of America, 2018
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-68878 (URN)10.1364/AO.57.003645 (DOI)000431880000003 ()2-s2.0-85046971352 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-05-24 (andbra)

Available from: 2018-05-24 Created: 2018-05-24 Last updated: 2018-08-21Bibliographically approved
Bergström, P., Michael, F. & Sjödahl, M. (2018). Virtual projective shape matching in targetless CAD-based close-range photogrammetry for efficient estimation of specific deviations. Optical Engineering: The Journal of SPIE, 57(5), Article ID 053110.
Open this publication in new window or tab >>Virtual projective shape matching in targetless CAD-based close-range photogrammetry for efficient estimation of specific deviations
2018 (English)In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 57, no 5, article id 053110Article in journal (Refereed) Published
Abstract [en]

A concept for targetless, computer-aided design (CAD)-based, close-range photogrammetry for online shape inspection is introduced. The shape of an object, which is arbitrarily located on a conveyor belt, is to be measured and compared with its nominal shape as defined by a CAD model. For most manufactured objects, deviations are only measured at a few given comparison points. These deviations can be estimated using local photogrammetry based on a priori geometrical information given by the CAD model and the comparison points. Our method results in faster output with higher precision, because we do not generate a shape representation of the entire measured object using typical photogrammetric methods. Images depicting the object from convergent angles are captured by an array of cameras in a precalibrated network, and the CAD model is matched and aligned, within the projective geometry of the camera network, to the depicted object in the images without the use of targets. An algorithm for solving this virtual projective targetless shape matching problem is presented.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Keywords
computer-aided design, close-range, matching, online, photogrammetry, shape
National Category
Reliability and Maintenance Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-68856 (URN)10.1117/1.OE.57.5.053110 (DOI)000435435300019 ()2-s2.0-85047752202 (Scopus ID)
Projects
SIVPRO
Note

Validerad;2018;Nivå 2;2018-05-28 (andbra)

Available from: 2018-05-22 Created: 2018-05-22 Last updated: 2018-12-14Bibliographically approved
Öhman, J. & Sjödahl, M. (2017). Axial Particle Positioning by Wavefront Parameterization using Chebyshev Polynomials and Off-axis Digital Holography. In: Digital Holography and Three-Dimensional Imaging: . Paper presented at Digital Holography and Three-Dimensional Imaging 2017, JeJu Island, South Korea, 29 May–1 June 2017. Washington: The Optical Society, Article ID M4A.3.
Open this publication in new window or tab >>Axial Particle Positioning by Wavefront Parameterization using Chebyshev Polynomials and Off-axis Digital Holography
2017 (English)In: Digital Holography and Three-Dimensional Imaging, Washington: The Optical Society , 2017, article id M4A.3Conference paper, Published paper (Refereed)
Abstract [en]

A particle can be axially positioned where its scattered light has a plane wavefront. The phase anomaly compared to a plane wave is fitted to 3D Chebyshev polynomial, where coefficients correspond to the axial position.

Place, publisher, year, edition, pages
Washington: The Optical Society, 2017
Series
Digital Holography and Three-Dimensional Imaging
Keywords
Particle Scattering, Digital Holography
National Category
Atom and Molecular Physics and Optics Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-64069 (URN)10.1364/DH.2017.M4A.3 (DOI)2-s2.0-85026326255 (Scopus ID)978-1-943580-28-6 (ISBN)
Conference
Digital Holography and Three-Dimensional Imaging 2017, JeJu Island, South Korea, 29 May–1 June 2017
Funder
Swedish Research Council, 621-2014-4906
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2018-04-16Bibliographically approved
Eppanapelli, L. K., Casselgren, J., Wåhlin, J. & Sjödahl, M. (2017). Investigation of snow single scattering properties of snow based on first order Legendre phase function. Optics and lasers in engineering, 91, 151-159
Open this publication in new window or tab >>Investigation of snow single scattering properties of snow based on first order Legendre phase function
2017 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 91, p. 151-159Article in journal (Refereed) Published
Abstract [en]

Angularly resolved bidirectional reflectance measurements were modelled by ap- proximating a first order Legendre expanded phase function to retrieve single scattering properties of snow. The measurements from 10 different snow types with known density and specific surface area (SSA) were investigated. A near infrared (NIR) spectrometer was used to measure reflected light above the snow surface over the hemisphere in the wavelength region 900 nm to 1650 nm. A solver based on discrete ordinate radiative transfer (DISORT) model was used to retrieve the estimated Legendre coefficients of the phase function and a cor- relation between the coefficients and physical properties of different snow types is investigated. Results of this study suggest that the first two coefficients of the first order Legendre phase function provide sufficient information about the physical properties of snow where the latter captures the anisotropic behaviour of snow and the former provides a relative estimate of the single scattering albedo of snow. The coefficients of the first order phase function were com- pared with the experimental data and observed that both the coefficients are in good agreement with the experimental data. These findings suggest that our approach can be applied as a qualitative tool to investigate physical properties of snow and also to classify different snow types.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Radiative transfer model, Scattering phase function, Snow, SSA, Reflectance spectrum, NIR spectrometer
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-60532 (URN)10.1016/j.optlaseng.2016.11.013 (DOI)000393264300016 ()2-s2.0-84998694302 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2016-12-19 (andbra)

Available from: 2016-11-18 Created: 2016-11-18 Last updated: 2018-09-13Bibliographically approved
Bergström, P., Fergusson, M., Folkesson, P., Runnemalm, A., Ottosson, M., Andersson, A. & Sjödahl, M. (2016). Automatic in-line inspection of shape based on photogrammetry. In: SPS16: . Paper presented at 7th Swedish Production Symposium, Lund, 25-27 October 2016. Lund: SPS16
Open this publication in new window or tab >>Automatic in-line inspection of shape based on photogrammetry
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2016 (English)In: SPS16, Lund: SPS16 , 2016, , p. 9Conference paper, Published paper (Refereed)
Abstract [en]

We are describing a fully automatic in-line shape inspection system for controlling the shape of moving objects on a conveyor belt. The shapes of the objects are measured using a full-field optical shape measurement method based on photogrammetry. The photogrammetry system consists of four cameras, a flash, and a triggering device. When an object to be measured arrives at a given position relative to the system, the flash and cameras are synchronously triggered to capture images of the moving object. From the captured images a point-cloud representing the measured shape is created. The point-cloud is then aligned to a CAD-model, which defines the nominal shape of the measured object, using a best-fit method and a feature-based alignment method. Deviations between the point-cloud and the CAD-model are computed giving the output of the inspection process. The computational time to create a point-cloud from the captured images is about 30 seconds and the computational time for the comparison with the CAD-model is about ten milliseconds. We report on recent progress with the shape inspection system.

Place, publisher, year, edition, pages
Lund: SPS16, 2016. p. 9
Series
Swedish Production Symposium ; 7
National Category
Mathematical Analysis Applied Mechanics Production Engineering, Human Work Science and Ergonomics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-60006 (URN)
Conference
7th Swedish Production Symposium, Lund, 25-27 October 2016
Projects
SIVPRO
Funder
VINNOVA
Available from: 2016-10-27 Created: 2016-10-27 Last updated: 2018-02-05Bibliographically approved
Eppanapelli, L. K., Friberg, B., Casselgren, J. & Sjödahl, M. (2016). Estimation of a low-order Legendre expanded phase function of snow (ed.). Paper presented at . Optics and lasers in engineering, 78, 174-181
Open this publication in new window or tab >>Estimation of a low-order Legendre expanded phase function of snow
2016 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 78, p. 174-181Article in journal (Refereed) Published
Abstract [en]

The purpose of this paper is to estimate the scattering phase function of snow from angularly resolved measurements of light intensity in the plane of incidence. A solver is implemented that solves the scattering function for a semi-infinite geometry based on the radiative transfer equation (RTE). Two types of phase functions are considered. The first type is the general phase function based on a low-order series expansion of Legendre polynomials and the other type is the Henyey-Greenstein (HG) phase function. The measurements were performed at a wavelength of 1310 nm and six different snow samples were analysed. It was found that a first order expansion provides sufficient approximation to the measurements. The fit from the first order phase function outperforms that of the HG phase function in terms of accuracy, ease of implementation and computation time. Furthermore, a correlation between the magnitude of the first order component and the age of the snow was found. We believe that these findings may complement present non-contact detection techniques used to determine snow properties.

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-4108 (URN)10.1016/j.optlaseng.2015.10.013 (DOI)000366769100021 ()2-s2.0-84947210191 (Scopus ID)1fb86369-88ce-4293-89e3-fae4460cfe1f (Local ID)1fb86369-88ce-4293-89e3-fae4460cfe1f (Archive number)1fb86369-88ce-4293-89e3-fae4460cfe1f (OAI)
Note
Validerad; 2015; Nivå 2; 20151028 (lavepp)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Khodadad, D., Singh, A. K., Pedrini, G. & Sjödahl, M. (2016). Full-field 3D deformation measurement: Comparison between speckle phase and displacement evaluation. Applied Optics, 55(27), 7735-7743
Open this publication in new window or tab >>Full-field 3D deformation measurement: Comparison between speckle phase and displacement evaluation
2016 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 55, no 27, p. 7735-7743Article in journal (Refereed) Published
Abstract [en]

The objective of this paper is to describe a full-field deformation measurement method based on 3D speckle displacements. The deformation is evaluated from the slope of the speckle displacement function that connects the different reconstruction planes. For our experiment, a symmetrical arrangement with four illuminations parallel to the planes (x,z) and (y,z) was used. Four sets of speckle patterns were sequentially recorded by illuminating an object from the four directions, respectively. A single camera is used to record the holograms before and after deformations. Digital speckle photography is then used to calculate relative speckle displacements in each direction between two numerically propagated planes. The 3D speckle displacements vector is calculated as a combination of the speckle displacements from the holograms recorded in each illumination direction. Using the speckle displacements, problems associated with rigid body movements and phase wrapping are avoided. In our experiment, the procedure is shown to give the theoretical accuracy of 0.17 pixels yielding the accuracy of 2 × 10-3 in the measurement of deformation gradients

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-59937 (URN)10.1364/AO.55.007735 (DOI)000383996900038 ()2-s2.0-8498881167 (Scopus ID)
Note

Validerad; 2016; Nivå 2; 2016-10-25 (andbra)

Available from: 2016-10-25 Created: 2016-10-25 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-4879-8261

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