Letter to the Editor
Sensitivity of a pyramidic Wave Front sensor in closed loop Adaptive Optics
R. Ragazzoni 1 and
J. Farinato 2
Received 17 June 1999 / Accepted 17 August 1999
The Pyramidic wavefront has a very interesting property: its SNR has a significant increase once the loop is closed, similarly to the Curvature Sensor and contrasting with the Shack-Hartmann one. This result in a gain comparing the Pyramidic and the Shack-Hartmann sensors. It is shown by a combination of descriptive and numerical arguments that this gain is of the order of for low order modes and drift linearly down to the Shack-Hartmann case at the highest spatial frequency sampled. A discussion of the overall gain (including a first estimation of the magnitude gain) and procedures to force a true system to work in closed loop fashion are sketched.
Key words: telescopes instrumentation: adaptive optics
This article contains no SIMBAD objects.
© European Southern Observatory (ESO) 1999
Online publication: October 4, 1999