Electronic dynamics in molecules and atoms takes place on the attosecond timescale. For the observation of such processes, measurement techniques with attosecond resolution are needed. High-harmonic generation (HHG) in gas medium provides an ultrashort light source on the attosecond timescale for observing, understanding and controlling light-induced process on this scale with the necessary time resolution. To be able to use these attosecond pulses to measure electron dynamics, they have to be characterized. For this characterization, the XUV spectrum is extremely important. The XUV spectrum not only contains the information about the photon energies of the pulses, but also temporal information such as the difference between a single isolated attosecond pulse or an attosecond pulse train. The Light Wave Synthesizer 20 generates intense femtosecond pulses with a peak power of 16 TW and a spectrum spanning over the region from 580 to 1000 nm. This allow one to generate attosecond pulses based on HHG in gas medium with 100 eV photon energy and up to 20 nJ pulse energy. The generated attosecond pulses can be observed with a photodiode to measure the energy, an XUV CCD used as a profiler and an XUV flat-field spectrometer. The detector of the flat-field spectrometer is an XUV CCD which records the diffracted beam from a grating. Hence, a certain pixel of the camera shows the intensity for a certain range of photon energies. However, the calibration from pixel to energy is not always fixed due to e.g. the alignment of the spectrometer. This pixel to photon energy calibration can be done either by using the harmonic peaks in the XUV spectra or theoretical analyses of the spectrometer structure. In this thesis, both methods are investigated and the results are in good agreement. Due to the analytical calibration has a lower error and faster to do, future measurements can be evaluated with the analytical method.

The intense few-cycle laser pulses play an important role in the investigations of laser-plasma interaction. However, one of the biggest challenges in their generation is the reduction of temporal intensity contrast by introducing undesired pre-pulses and a long pedestal. Two techniques were investigated in this work to improve the contrast. First, the crossed-polarized wave (XPW) generation was optimized to get clean pulse. The conditions for XPW were optimized including crystal thickness and maximal background pressure in the vacuum cell. Second, the method of elliptical polarization rotation (EPR) in a gas-filled hollow-core fiber (HCF) was implemented to produce both broadened and cleaned pulse, since its setup is much simpler. For the tested EPR-based nonlinear filter, the spectral smoothening and broadening were obtained. The contrast of cleaned pulse was characterized providing 2 order of magnitude contrast enhancement, while it had a high average power of 80 mW. The EPR-based nonlinear filter is a promising simplified technique in the development of intense few-cycle lasers.

To observe electron dynamics in molecules and atoms which takes place on the attosecond timescale, single isolated attosecond pulses are required utilized in performing pump–probe experiments. The Light Wave Synthesizer 20 generates intense sub-5 fs pulses with a peak power of 16 TW and a broad spectrum. This offers a chance of generating isolated attosecond pulses via high harmonic generation (HHG) in gas medium. In this project, the variation of cutoff energy of HHG with different intensities of the driving laser was investigated. In addition, an isolated attosecond pulse with an Fourier-limited pulse duration of 188 as is produced with a selection of 15 eV around the cutoff region. Moreover, one optimization method refer to GDD scan was illustrated to optimize the HHG cutoff and continuum.

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Optical Coherence Tomography (OCT) is a non-invasive high-resolutionmethod for measuring the reectance of scattering media in 1/2/3D, e.g.skin. The method has been used in a number of dierent medical elds andfor measurement of tissue optical properties.The software developed in this thesis is able to display features hidden ina shadowed volume by adding multiple OCT measurements taken at obliqueangles, a technique here called Multiple-Angle Oblique Optical CoherenceTomography (MAO-OCT).Three dierent objects with were measured at 5 to 9 angles. The measurementswere automatically and manually aligned in the software. They werealso tested with 6 dierent high pass intensity lters (HPIF) and reduced insize using 4 dierent methods to speed up calculations.The software's automatic alignment was tested with one tilted computergenerated test at 9 angles and with 5 dierent shadow strengths.With MAO-OCT it is possible to remove some eects of shadows in OCT,though it comes with a cost of reduced sharpness. The errors depend muchon the dierences in index of refraction in the sample.The software managed to automatically align 90% of the articial measurements,and 60% of the OCT measurements. The shadow strength andthe resize method had no noticeable eect on the automatic alignment of themeasurements.

Peripheral vision plays an important role for visually impaired people with central field loss. Furthermore, recent studies show that defocus in the image on the peripheral retina might influence the development of myopia. Apart from the refractive errors and astigmatism, off-axis aberrations such as coma and transverse chromatic aberration (TCA) also influence the image quality on the peripheral retina. Theory shows that the amount of TCA is quite large in peripheral vision especially in large off-axis angles. The aim of this study is to develop a method to measure the amount of TCA in the peripheral field of view of the human eye. The method which was used for this study was subjective and the amount of TCA was measured in the left eye of the three volunteer adult subjects. The method was based on measuring the TCA as a chromatic difference of position outside of the eye. The measurements were done in the nasal retina of the eye in seven angles from 0 deg eccentricity (fovea) to 60 deg eccentricity. To compare the experimental results with theoretical values two schematic eye models were implemented in ZEMAX optical design software; a reduced eye model and a wide angle eye model. The results showed the expected increase of TCA with off-axis angle. The measurements for two subjects were in good agreement with the eye models. The magnitudes for TCA varied between subjects, one reason for this can be related to the different shapes of the eye in different subjects. The third subject had different values for TCA. This difference led us to investigate the reliability and the repeatability of the method in more detail.

Trapped Rydberg ions with their extraordinary properties serve as very good candidatesfor quantum computing and quantum simulation. The strong dipole-dipoleinteraction in Rydberg ions enables fast entangling gates between qubits. The entanglementdoes not involve motional quantum state to exchange information, whichmakes it suitable to perform gate operations in a long ion string. In this report,preliminary studies for cooling the trapped ions using polarization gradient coolingand addressing of single ion in a long ion string have been done. The results showthat for cooling of multiple ions in a linear chain, a combination of Doppler coolingand polarization gradient cooling provides better cooling as compared to Dopplercooling alone. Simulations for single ion addressing shows that the focusing of thebeams on the ions can be further improved by using additional optics described bythe simulation. Better focusing is essential to deliver higher laser intensities to theion such that the Rabi frequency is higher. This is important for improving the delity of gate operation in long ion strings.

Irradiation induced void swelling is problematic for the application of austenitic steels under high dose irradiation. In this thesis, the swelling is characterized by dislocation bias. The dislocation bias is obtained using the finite element method, accounting for fcc copper and nickel under electron irradiation. The methodology is implemented with the interaction energies between an edge dislocation and point defects. Analytically derived interaction energies, which are based on elasticity theory, are compared with interaction energies obtained from atomistic model using semi-empirical atomic potentials as physics basis. The comparison shows that the description of analytical interaction energies is inaccurate in the dislocation core regions. The bias factor dependence on dislocation density and temperature is presented and discussed. At high temperatures or low dislocation densities, the two approaches tend to converge. However, the dislocation bias based on the interaction energies from the two approaches, reveals larger discrepancy for nickel than for copper. The impact on dislocation bias from the different stacking fault energies of copper and nickel is elaborated. Nickel, which has a larger stacking fault energy, is predicted to have larger swelling rate than copper under the same irradiation conditions. / <p>QC 20130530</p>

Single-particle imaging, or SPI, is a method used to obtain the three-dimensional structure of particles. Repeatedly aiming X-rays at samples of a particle produces diffraction patterns, which are combined to a best-fit three-dimensional model of the particle. SPI of proteins can be improved by orienting the protein before imaging. Protein dipole orientation makes use of a protein's dipole moment and an external electric field to generate torque, which can orient the protein. A protein subject to an electric field may however result in damage of the protein's geometrical structure, or insufficient protein orientation, depending on the magnitude of the electric field. Sufficient protein orientation without substantial protein damage is possible in an interval of electric field strengths. The results in this report reveal that the method of SPI can be further improved. With a protein being fully oriented in an electric field, it is possible to reduce the electric field strength and yet sustain sufficient orientation, with some constraints. Longer times for imaging and less structural damage to the protein are hence possible. This study implements Molecular Dynamics (MD) and the most extensively used open-source MD software, GROMACS, with ubiquitin as a sample protein. / Single-particle imaging, eller SPI, är en metod som används för att erhålla den tredimensionella strukturen hos partiklar. Genom att upprepade gånger rikta röntgenstrålar mot prover av en partikel produceras diffraktionsmönster, som kombineras till en anpassad tredimensionell modell av partikeln. SPI av proteiner kan förbättras genom att i förväg rikta proteinet. I dipolorientering av ett protein utnyttjas proteinets dipolmoment och ett yttre elektriskt fält för att generera vridmoment, vilket kan rikta proteinet. Ett protein som utsätts för ett yttre elektriskt fält kan dock resultera i att proteinets geometriska struktur skadas, eller att proteinets riktning avviker avsevärt, beroende på magnituden av det elektriska fältet. Det är möjligt att rikta ett protein inom ett intervall av elektrisk fältstyrka utan att proteinet skadas avsevärt. Resultaten i denna rapport avslöjar att metoden för SPI kan förbättras ytterligare. Med ett protein som i förväg riktats i ett elektriskt fält är det möjligt att sänka fältstryrkan och ändå upprätthålla riktningen, med vissa begränsningar. Längre tid för avbildning och mindre omfattande strukturella skador möjliggörs med detta. Denna studie implementerar Molecular Dynamics (MD) och den mest använda programvaran med öppen källkod för MD-simuleringar, GROMACS, med proteinet ubiquitin som prov.

The X-ray tube is one of the most common types of X-ray sources, which is widely used in research laboratories and industry. Electrons are accelerated towards a metallic target to generate X-ray photons, thus creating a significant thermal load on the metal. In order to reduce the risk of damage, some techniques, such as the focus line principle or the installation of a very thin target, are implemented in most cases. In addition, the geometry of the target is chosen to maximise the amount of X-rays for the intended application. The aim of this thesis is to investigate how the incident angle of the electron beam, consequence of the line focus principle, and the thickness of the target influence the total photon yield of the source. Monte Carlo simulations of electron/photon transport have been made with a modified version of the PENELOPE program using a novel variance reduction technique. The results from the calculations are validated with experiments conducted with a prototype source, in the laboratory of Excillum AB. Since thermal capabilities and X-ray yield have opposite dependence on target angle and thickness, by combining the thermal results from Sara Högnad$\acute{\mathrm{o}}$ttir's thesis and the ones produced in this thesis, it is possible to isolate an optimal configuration of the source. In this geometry, the best compromise between high brightness and high maximum allowed power is found.