Lyot-based ultra-fine pointing control system for phase mask coronagraphs
Abstract
Detection of extrasolar companions benefits from coronagraphs with high throughput and the capability to work at the smallest possible inner working angle (IWA). The Subaru Telescope Coronagraphic Extreme AO (SCExAO) is a flexible, high performance coronagraphic system that can detect high contrast structures as close as 1λ/D. To further enhance the IWA of the system, we are modifying the instrument to support phase mask coronagraphy with a goal IWA < 1λ/D. We will show how both the high order wavefront (WF) calibration and low order WF control will be performed in this new configuration. To improve SCExAO's high order WF calibration capability at the focal plane, we will employ the Self Coherent Camera approach to control and cross calibrate electric field in the focal plane. Tip tilt and few other low order modes will be measured by using coronagraphic stellar residue reflected from the Lyot mask at the pupil plane for fast and accurate closed loop pointing control by low order wavefront sensor (LOWFS). We will present simulation results predicting the performance of the new configuration, as well as preliminary tests in the laboratory.
- Publication:
-
Proceedings of the Third AO4ELT Conference
- Pub Date:
- December 2013
- DOI:
- 10.12839/AO4ELT3.12667
- arXiv:
- arXiv:1310.3895
- Bibcode:
- 2013aoel.confE...7S
- Keywords:
-
- AO systems for ELTs;
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- 7 pages, 5 figures, Proceedings of AO4ELTs3 conference, Paper 12667, Florence, Italy, May 2013