Development of a new Infrared Pyramid Wavefront Sensor

One possibility of increasing the achievable sky coverage of an adaptive optics system compensating the optical aberrations due to atmospheric turbulence for astronomical observations is sensing the wavefront at near-infrared wavelengths, where many bright stars are found, which can be used as guide stars and have no visible counterparts. A pyramid wavefront sensor was chosen due to its advantages over the Shack-Hartmann sensor. It is expected to achieve a gain in terms of sensitivity, raising the limiting magnitude, when used in closed-loop regime. In this work the possibility of building such an instrument has been studied in the framework of a project called PYRAMIR, which will implement a new wavefront sensor in the adaptive optics system at the Calar Alto 3.5m telescope. An analytical model for the way in which atmospheric turbulence increases the linear range of this sensor at the cost of lower sensitivity, as usually is done through a mechanical modulation of the light beam, has been presented. Studies at the telescope, in the laboratory and through simulations show the possibility of using the pyramid wavefront sensor without any extra modulation. An experimental laboratory setup and numerical simulations of a full adaptive optics system were the main tools for establishing the optical requirements for the new instrument. Issues like the pyramid requirements and specifications, the effects of modulation and non-common path aberrations and spatial filters and their effects on the sensor have been analyzed in this way. The results were then directly applied in the design of PYRAMIR.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2005

Author dc:creator

• Büchler de Matos Costa Paccetti Correia, Joana

Contributors dc:contributor

• Mundt, Reinhard

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/5321

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:5321