| 1. |
- Andersson, Angelica, et al.
(författare)
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Digital speckle-pattern interferometry: fringe retrieval for large in-plane deformations with digital speckle photography
- 1999
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Ingår i: Applied Optics. - : Optical Society of America. - 1559-128X .- 2155-3165. ; 38:25, s. 5408-5412
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Tidskriftsartikel (refereegranskat)abstract
- The compensation of large in-plane motions in digital speckle-pattern interferometry (DSPI) with the use of digital speckle photography (DSP) is demonstrated. Ordinary recordings of DSPI are recombined and analyzed with DSP. The DSP result is used to compensate for the bulk speckle motion prior to calculation of the phase map. This results in a high fringe contrast even for deformations of several speckle diameters. In addition, for the case of an in-plane deformation, it is shown that the absolute phase change in each pixel may be unwrapped by use of the DSP result as an initial guess. The principles of this method and experiments showing the in-plane rotation of a plate and the encounter of two rounded plates are presented
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| 2. |
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| 3. |
- Andersson, Angelica, et al.
(författare)
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TV shearography : quantitative measurement of shear-magnitude fields by use of digital speckle photography
- 2000
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 39:16, s. 2565-2568
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Tidskriftsartikel (refereegranskat)abstract
- Digital speckle photography combined with TV shearography is developed for precise measurement of the magnitude of the shear field in a linear shear configuration. As an application the method is implemented to determine the slope-change variations of a three-dimensional object with TV shearography in which the shear magnitude is obtained with the digital speckle photography technique
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| 4. |
- Bergström, Per, 1981-, et al.
(författare)
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Automatic in-line inspection of shape based on photogrammetry
- 2016
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Ingår i: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings. - Lund : Swedish Production Academy. ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 5. |
- Brugés, Javier Mauricio
(författare)
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Surface characterization methods for quality assessment of polyethylene-coated paperboard
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In manufacturing processes, the quality of a product often depends on its surface, and careful control of surface properties is critical to meet customer requirements. A thin layer of polyethylene (PE) is applied to paperboard to increase barrier functionality and high optical quality of the product. For PE-coated paperboard, product quality inspection is performed at the end of the manufacturing process by taking a portion of the reel to the laboratory for quality inspection. These associated offline characterization methods are destructive and time consuming and are representative of only a small portion of the product.The overall goal of this thesis is to provide new methods to characterize the Surface properties of PE-coated paperboard. Specifically, to determine imaging techniques for measuring surface parameters that affect its barrier functionality and surface roughness.In this thesis, two methods for surface characterization of PE-coated paperboard are presented to quantify the two most important product-related quality parameters, i.e. barrier functionality and optical quality, which are affected by the presence of defects in the coating and by the surface roughness of the product, respectively. First, a full-Stokes imaging polarimeter (FSIP) is used to detect the presence of PE-coated material and to distinguish between coated and uncoated samples at the pixel level. Second, a three-dimensional scanning electron microscope (3D SEM) is employed to calculate the Surface roughness of PE-coated paperboard. These surface characterization techniques offer an advantage over the industry standard due to the high speed and non-contact nature of the measurement, while increasing the throughput of the sample surface parameters studied.A classification accuracy of 99, 74% is achieved using a FSIP to distinguish between PE- and non-PE-coated paperboard at pixel level. Using the 3D SEM technique to measure the topography of PE-coated samples results in a faster method that is comparable in accuracy to a chromatic confocal microscope (CCM). The surface roughness measured with the 3D SEM differs from the standard method by up to 6% and good agreement with statistical parameters is found.In general, surface analysis of PE-coated is often a complex and difficult task for imaging techniques and suitable methods need to be evaluated for their sensitivity to measure the desired surface parameters. The presented characterization techniques inspect larger areas of PE-coated paperboard compared to current industry standards. These methods provide a quantitative solution for surface characterization to inspect the surface parameters necessary to assure the product’s quality.
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| 6. |
- Dahlberg, Tobias, 1990-
(författare)
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KNOW YOUR ENEMY : Characterizing Pathogenic Biomaterials Using Laser Tweezers
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diseases caused by pathogenic agents such as bacteria and viruses result in devastating costs on personal and societal levels. However, it is not just the emergence of new diseases that is problematic. Antibiotic resistance among bacteria makes uncomplicated infections difficult and lethal. Resilient disease-causing spores spread in hospitals, the food industry, and water supplies requiring effective detection and disinfection methods. Further, we face complex neurological diseases where no effective treatment or diagnostic methods exist. Thus, we must increase our fundamental understanding of these diseases to develop effective diagnostic, detection, disinfection, and treatment methods.Classically, the methods used for detecting and studying the underlying mechanics of pathogenic agents work on a large scale, measuring the average macroscopic behavior and properties of these pathogens. However, just as with humans, the average behavior is not always representative of individual behavior. Therefore, it is also essential to investigate the characteristics of these pathogens on a single cell or particle level. This thesis develops and applies optical techniques to characterize pathogenic biomaterial on a single cell or particle level. At the heart of all these studies is our Optical Tweezers (OT) instrument. OT are a tool that allows us to reach into the microscopic world and interact with it. Finally, by combining OT with other experimental techniques, we can chemically characterize biomaterials and develop assays that mimic different biological settings. Using these tools, we investigate bacterial adhesion, disinfection, and detection of pathogenic spores and proteins.Hopefully, the insights of these studies can lessen the burden on society caused by diseases by helping others develop effective treatment, diagnostic, detection, and disinfection methods in the future.
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| 7. |
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| 8. |
- Mohan, N. Krishna, et al.
(författare)
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Optical configuration for TV holography measurement of in-plane and out-of-plane deformations
- 2000
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 39:4, s. 573-577
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Tidskriftsartikel (refereegranskat)abstract
- A novel TV holography method is proposed for parallel evaluation of in-plane and out-of-plane deformation fields. The method permits a trade-off between in-plane and out-of-plane measuring sensitivity. A four-exposure, four-frame phase shifting technique is used in the experiments; the experimental results for an aluminum specimen subjected to both rotation in its own plane and a bending couple load at the center are presented
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| 9. |
- Mohan, N. Krishna, et al.
(författare)
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Optical configurations in TV holography for deformation and shape measurement
- 2000
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Ingår i: Lasers in engineering (Print). - 0898-1507 .- 1029-029X. ; 10:2, s. 147-159
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, TV holography is extensively implemented for determination of deformation and surface shape of diffusely reflecting surfaces. Such investigations are of primary importance in many applications, because these physical parameters are related to the functionality, integrity and performance of the engineering objects. In this paper, a new approach for determination of deformation and surface shape using simple optical configurations is presented. Description of each configuration, theory of fringe formation and the measuring sensitivity are discussed. Experimental results using four frame phase shifting technique are illustrated.
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| 10. |
- Molin, Nils-Erik, et al.
(författare)
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Digital speckle photography combined with speckle interferometry
- 2001
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Ingår i: Second International Conference on Experimental Mechanics, 29 November - 1 December 2000, Singapore. - Bellingham, Wash : SPIE - International Society for Optical Engineering. - 0819439983
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Konferensbidrag (refereegranskat)
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