Adaptive optics for phase and polarization control

Thesis

Adaptive optics (AO) is a powerful tool for microscopy. It helps to improve the image quality and resolution by correcting the aberrations that arise in the optical system or through external disturbance. Most AO technologies concern phase distortion, which is the main issue in the mainstream microscopies.

However, the correction is limited by the capabilities of the adaptive optical devices, e.g. in correction range and correction accuracy. Apart from that, phase distortion is not the only aberration that can affect microscopes. Polarization error is also a major concern for some polarization-sensitive microscopes such as Stimulated Emission Depletion Microscopy (STED) and Structured Illumination Microscopy (SIM).

Therefore, in this thesis, I firstly investigated the capabilities and limitations of a phase correction device, a deformable mirror (DM), specifically its correction range and accuracy based on Zernike mode aberrations. Then an adaptive polarization control (APC) system was developed through both hardware and software aspects. The APC consists of polarization state generator (PSG) and polarization state analyzer (PSA). The two modules were investigated separately first and then integrated together.

The system functionality was then demonstrated using different kinds of samples. Results show that this system is able to correct the external birefringence disturbance dynamically and the measurements could be tailored to the ability of prior knowledge about on the samples. This system could be combined with conventional phase AO methods to provide further improvements in system correction in applications ranging from quantum optics to microscopy imaging.

Authors: Dai, Y

• DOI: 10.5287/ora-9gedeyzd7
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English