Advanced Wavefront Sensors for Enhanced Adaptive Optics

Ground-based telescopes rely on adaptive optics (AO) systems to correct wavefront distortions that result from light propagating through Earth's turbulent atmosphere. In an AO system, the wavefront sensor (WFS) detects and reconstructs the input wavefront phase and amplitude. Current industry-leading WFS designs, such as the Shack-Hartmann WFS (SHWFS), lack vital sensing capabilities such as a broad spatial frequency capture range and high photon-efficiency, limiting the use of diffraction-limited observations for various science cases of interest. More accurate and photon-sensitive WFS designs are needed to advance the next generation of ground-based telescopes and instruments.

This dissertation investigates and develops the Fresnel WFS (FWFS) and Zernike WFS (ZWFS) as alternative designs to overcome the current state-of-the-art. It is shown that the FWFS is more accurate than an equivalent SHWFS, providing sensitivity to a broad range of spatial frequencies, a large capture range, robustness to scintillation, and an increased photon-efficiency. These advantages establish the FWFS as a promising candidate for a variety of AO applications for both astronomy and industry. Future investigations should study and improve the sensor's slow operating frequency, which results from the sensor's non-linear reconstruction algorithm.