Superchirality is a property of light with not yet fully discovered future possibilities in industry and research. In this research, an attempt to obtain a bright superchiral lattice is made by...Show moreSuperchirality is a property of light with not yet fully discovered future possibilities in industry and research. In this research, an attempt to obtain a bright superchiral lattice is made by superposing four laser beams in a particular configuration. Additionally, this superposition should theoretically lead to homogeneous electric fields without modulation, which is potentially useful in microscopy. Recording the field with a simple CMOS camera and observing its fast Fourier transform gives rise to aliasing effects due to undersampling caused by the fact that interference occurs at a subpixel level. This phenomenon is investigated by numeric and analytic simulations. By rotation of the camera, pixel superresolution was achieved, which effectively enables the possibility to investigate the interference patterns at a subpixel level and hence measure the angle between pair of beams with good accuracy. With newly developed beam alignment methods we have achieved and confirmed a beam alignment that is sufficient for production of bright superchirality lattices.Show less
Drizzle is an algorithm to combine multiple shifted images into one high quality image. In this thesis the drizzle algorithm is applied to datasets of the low-energy electron microscope (LEEM). We...Show moreDrizzle is an algorithm to combine multiple shifted images into one high quality image. In this thesis the drizzle algorithm is applied to datasets of the low-energy electron microscope (LEEM). We show that drizzle provides better images than the currently used shift-and-add method. However, increasing the resolution of the output image by drizzle introduces some artifacts limiting the resolution of drizzled images. Further research is needed to eliminate these artifacts to improve the resolution of the drizzled LEEM images.Show less
Over the last few decades, several methods have been explored and applied to circumvent the Abbe-Rayleigh diffraction limit, probably most importantly, stochastic super-resolution fluorescence...Show moreOver the last few decades, several methods have been explored and applied to circumvent the Abbe-Rayleigh diffraction limit, probably most importantly, stochastic super-resolution fluorescence microscopy methods. Another possibility, relying only on linear classical optics, is to exploit optical superoscillations, and is far less explored to date. In this project we explore the use of optical vortices for super-resolution far-field imaging. For this, we investigate strongly focused optical fields using a number of theoretical methods, we implement an experiment where a micro-pinhole is scanned through the focus, and, explore spin-orbit interactions of strongly focused optical fields. We find that our micron-sized pinhole is able to discern structures much smaller than its own size and leads to an enhancement of the spin-orbit interaction. Our method can be implemented as a simple and fast tool for characterizing the intensity distribution of a focused field with high resolution.Show less
Complex cellular processes can be characterised using single particle tracking techniques (SPT). ‘Labels’ such as metal nanoparticles are introduced into cells and tracked to reveal molecular...Show moreComplex cellular processes can be characterised using single particle tracking techniques (SPT). ‘Labels’ such as metal nanoparticles are introduced into cells and tracked to reveal molecular trajectories. Many current techniques are based on fluorescence microscopy, and have nanometre-resolution. To accurately probe cellular processes, a technique must also have long-term 3D in-vivo observing capability with a minimal toxic effect. Gold nanorods (GNRs) in two-photon microscopy is a promising technique. GNRs are non-toxic, easily functionalisable, and exhibit a bright two-photon fluorescence. However, the theoretical positional accuracy for this technique is not yet known. Furthermore, the detailed trajectory data present statistical challenges. We have addressed these issues here numerically, using simulated image data. We found the accuracy to be between 5.2nm and 8.9nm for stationary GNRS, dependent on the separation between slices. We also found that diffusive movement of a nanorod lowers the accuracy, at worst case to 31.8nm. We have also investigated optimising the extraction of behaviour properties from MSD plots, and have used Welsh’s test to detect transitions. GNRs in two-photon microscopy has been shown to be a very accurate technique, and its trajectory data can yield accurate behavioural information. The fit of the PSF may be improved, but the techniques already compares well against others.Show less
