Laser Guide Star Adaptive Optics Systems for the Lick Observatory Telescopes

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Session 51 -- Instrumentation
Display presentation, Wednesday, 9:20-6:30, Pauley Room

[51.11] Laser Guide Star Adaptive Optics Systems for the Lick Observatory Telescopes

D.T.Gavel, S.S.Olivier, C.E.Max, H.W.Friedman, J.M. Brase, J.R.Morris, K.Avicola, J.T.Salmon, D.A.Rapp, H.D.Bissinger, K.E.Waltjen (LLNL)

We are building adaptive optics systems for the Lick Observatory 3 meter (Shane) and 1 meter (Nickel) telescopes. These systems can use either natural starlight or laser-generated artificial guide star light as a wavefront reference source in order to make corrections for the aberrations introduced by atmospheric seeing and thereby achieve near diffraction-limited resolution. For the Shane telescope, a 10 Watt laser system is being designed that can be projected through the Coude Auxiliary Telescope, a 1 meter aperture siderostat located just outside the dome and about 6 meters off-axis from the 3 meter's centerline. This paper will discuss the system design issues and tradeoffs involved in constructing these systems. We predict that a 69 actuator deformable mirror system will give reasonable Strehl performance in J and K bands on the 3 meter and will also perform well in the visible on the 1 meter. We also analyze the performance of a 127 actuator upgrade system. Almost full sky coverage is possible with the laser guide star (this is limited only by the availability to find a suitable natural star for tip-tilt correction and the physical limitations of pointing the laser). The natural guide star system will be limited to imaging within a small region around bright reference sources. The laser guide star system uses resonant backscatter from the mesospheric sodium layer at 90 km altitude. The photon return has been predicted by computer model and verified by experiments performed at LLNL over the past year.

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