Shack-Hartmann based atmospheric turbulence profiler using SLODAR

Sahoo, Ayan (2025) Shack-Hartmann based atmospheric turbulence profiler using SLODAR. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Ayan Sahoo (20MS013)) 20MS013_Thesis_file.pdf Restricted to Repository staff only Download (4MB)

Abstract

Understanding atmospheric turbulence is crucial for optimizing adaptive optics (AO) systems in large telescopes. Observations of exoplanets, galaxy and star clusters and even solar system objects from terrestrial telescopes are hugely benefitted by AO systems, and the design and implementation of different variants of AO require measuring ground layer turbulence as well as at altitudes extending a few kilometres above the ground. Slope Detection and Ranging (SLODAR) is a Shack-Hartmann Wavefront Sensor (SHWFS)–based technique that reconstructs turbulence strength profiles at different altitudes using binary star images. This study presents a numerical simulation of SLODAR using the open-source HCIPy package, which enabled us to generate phase screens, propagate wavefronts, etc. We simulated varying turbulence conditions at different heights and analysed the resulting spot patterns on an SHWFS. By examining the retrieved SHWFS spot pattern of the binary star and estimating the input parameters, we validate the accuracy of SLODAR in reconstructing atmospheric conditions. This approach allows us to explore a range of realistic turbulence scenarios that telescopes might encounter, providing valuable insights into AO system design. In particular, our work has strong implications for Multi-Conjugate Adaptive Optics (MCAO), which requires accurate atmospheric profiling to correct turbulence at particular altitudes over wide fields of view. MCAO is essential for high-resolution observations of extended astronomical objects such as globular clusters, stellar populations in galaxies, galactic centres near supermassive black holes, solar system planets and even their moons.

Actions (login required)

View Item