Lick Observatory adaptive optics wavefront sensor upgrades

David Palmer; Donald Gavel; Elinor Gates

doi:10.1117/12.672307

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28 June 2006 Lick Observatory adaptive optics wavefront sensor upgrades

David Palmer, Donald Gavel, Elinor Gates

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Proceedings Volume 6272, Advances in Adaptive Optics II; 62721D (2006) https://doi.org/10.1117/12.672307
Event: SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida , United States

Abstract

The wavefront sensor camera and tip/tilt sensor APDs that were on Lick Observatory's Shane 3 Meter Adaptive Optics system were over a decade old and showing their age. They were recently upgraded. The first upgrade was to convert from quad-APDs in the laser guidestar mode natural star tip-tilt sensor to a sensitive low-noise CCD. The new CCD in this position, an 80x80 E2V CCD-39 inside a SciMeasure camera, has a low enough read noise, ~3 e-/pixel, that the tip/tilt measurement in closed-loop operation is photon noise limited and thus benefits from the improved quantum efficiency of the CCD. We have demonstrated on-sky up to two magnitudes of improvement in viable tip/tilt star brightness, which greatly extends the available sky coverage in the laser guidestar AO mode. Also, the increased field of view of the new tip/tilt sensor provides a much more reliable means of acquiring and locking on dim tip/tilt stars, making the whole system operationally more efficient. In the second phase of the upgrade project, the high order wavefront sensor has been replaced, also with a CCD-39 chip in a SciMeasure camera. In this paper we will describe these upgrades and present preliminary performance results.

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David Palmer, Donald Gavel, and Elinor Gates "Lick Observatory adaptive optics wavefront sensor upgrades", Proc. SPIE 6272, Advances in Adaptive Optics II, 62721D (28 June 2006); https://doi.org/10.1117/12.672307

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