Polarimetric and hyperspectral imaging methods for characterisation of bio- and nanomaterials
MetadataShow full item record
- Institutt for fysikk 
Presented here is the development of a time gated Raman spectrometer, a new method for designing polarimeters, testing of an overdetermined Mueller matrix imaging ellipsometer and Mueller matrix imaging of collagen fibre directions and silicon strain. In addition, a new method, spectral correlation, for analysing hyperspectral images, is developed, implemented and tested. The time gated Raman spectrometer is capable of gating away long lifetime luminescence (> 2 ns), by using a time gated ICCD and a 2 ns pulsed Nd:YAG laser. Furthermore, the system can be used to study UV resonance Raman effects, due to the third (355 nm) and fourth (266 nm) order harmonic excitations available. For optimising broadband polarimeters, genetic algorithms are employed. The resulting polarimeters are demonstrated to have a lower noise propagation and a broader spectral range, compared to previous commercial and patented designs. One of the designs is realised as a Mueller matrix liquid crystal variable retarder based ellipsometer. Its performance is in good agreement with computer optimised models. For calibrating the instrument, an extended version of the eigenvalue calibration method is employed. Mueller matrix imaging is used together with state of the art decomposition methods to image collagen fibre orientations in cartilage and tendon. 3D directional imaging of the collagen fibres is achieved by using different angles of incidence upon the sample and a new method for calculating the fibre direction from the linear retardance. The method uses an effective medium approach to justify that the slow axis is along the direction of the fibres. A similar approach is used to study strain in silicon wafers. Lastly, a spectral correlation method for analysing hyperspectral fluorescence images is developed and demonstrated to be good for analysing double stained amyloid plaques in mice. The resulting analysis allows for calculating the radius dependent mean and standard deviations for a set of plaques as a function of radius. By studying amyloid plaques from mice of different ages, it was found that there were significant changes with age in the structure of the plaques. Furthermore, the method was found to work well for analysing multi-component Raman spectra, where it detected small amounts of tetrahydrofuran in water.
Has partsLetnes, Paul Anton; Nerbo, Ingar Stian; Aas, Lars Martin Sandvik; Ellingsen, Pal Gunnar; Kildemo, Morten. Fast and optimal broad-band Stokes/Mueller polarimeter design by the use of a genetic algorithm. Optics Express. (ISSN 1094-4087). 18(22): 23095-23103, 2010. 10.1364/OE.18.023095.
Aas, Lars Martin Sandvik; Ellingsen, Pål Gunnar; Fladmark, Bent Even; Letnes, Paul Anton; Kildemo, Morten. Overdetermined broadband spectroscopic Mueller matrix polarimeter designed by genetic algorithms. Optics Express. (ISSN 1094-4087). 21(7), 2013. 10.1364/OE.21.008753.
Aas, Lars Martin Sandvik; Ellingsen, Pål Gunnar; Kildemo, Morten; Lindgren, Mikael. Dynamic response of a fast near infra-red Mueller matrix ellipsometer. Journal of Modern Optics. (ISSN 0950-0340). 57(17): 1603-1610, 2010. 10.1080/09500340.2010.515750.
Aas, Lars Martin Sandvik; Ellingsen, Pål Gunnar; Kildemo, Morten. Near infra-red Mueller matrix imaging system and application to retardance imaging of strain. Thin Solid Films. (ISSN 0040-6090). 519(9): 2737-2741, 2011. 10.1016/j.tsf.2010.12.093.
Ellingsen, Pål Gunnar; Lilledahl, Magnus Borstad; Aas, Lars Martin Sandvik; Davies, Catharina De Lange; Kildemo, Morten. Quantitative characterization of articular cartilage using Mueller matrix imaging and multiphoton microscopy. Journal of Biomedical Optics. (ISSN 1083-3668). 16(11): 116002-1, 2011. 10.1117/1.3643721.
Ellingsen, Pål Gunnar; Aas, Lars Martin Sandvik; Hagen, Vegard Stenhjem; Kumar, Rajesh; Lilledahl, Magnus Borstad; Kildemo, Morten. Mueller matrix three-dimensional directional imaging of collagen fibers. Journal of Biomedical Optics. (ISSN 1083-3668). 19(2), 2014. 10.1117/1.JBO.19.2.026002.
Ellingsen, Pål Gunnar; Reitan, Nina Kristine; Pedersen, Brede Dille; Lindgren, Mikael. Hyperspectral analysis using the correlation between image and reference. Journal of Biomedical Optics. (ISSN 1083-3668). 18(2), 2013.
Ellingsen, Pål Gunnar; Nyström, Sofie; Reitan, Nina Kristine; Lindgren, Mikael. Spectral correlation analysis of Amyloid beta plaque inhomogeneity from double staining experiments. Journal of Biomedical Optics. (ISSN 1083-3668). 18(10), 2013. 10.1117/1.JBO.18.10.101313.
Ellingsen, P. G.; Lindgren, M.. Design and test of a Raman spectroscopic system based on a time-gated intensified CCD. .