ShaneAO: wide science spectrum adaptive optics system for the Lick Observatory

A new high-order adaptive optics system is now being commissioned at the Lick Observatory Shane 3-meter telescope in California. This system uses a high return efficiency sodium beacon and a combination of low and high-order deformable mirrors to achieve diffraction-limited imaging over a wide spectrum of infrared science wavelengths covering 0.8 to 2.2 microns. We present the design performance goals and the first on-sky test results. We discuss several innovations that make this system a pathfinder for next generation AO systems. These include a unique woofer-tweeter control that provides full dynamic range correction from tip/tilt to 16 cycles, variable pupil sampling wavefront sensor, new enhanced silver coatings developed at UC Observatories that improve science and LGS throughput, and tight mechanical rigidity that enables a multi-hour diffraction- limited exposure in LGS mode for faint object spectroscopy science.Comment: 11 pages, 10 figures. Presented at SPIE Astronomical Telescopes + Instrumentation conference, paper 9148-7

Optical calibration of large format adaptive mirrors

Adaptive (or deformable) mirrors are widely used as wavefront correctors in adaptive optics systems. The optical calibration of an adaptive mirror is a fundamental step during its life-cycle: the process is in facts required to compute a set of known commands to operate the adaptive optics system, to compensate alignment and non common-path aberrations, to run chopped or field-stabilized acquisitions. In this work we present the sequence of operations for the optical calibration of adaptive mirrors, with a specific focus on large aperture systems such as the adaptive secondaries. Such systems will be one of the core components of the extremely large telescopes. Beyond presenting the optical procedures, we discuss in detail the actors, their functional requirements and the mutual interactions. A specific emphasys is put on automation, through a clear identification of inputs, outputs and quality indicators for each step: due to a high degrees-of-freedom count (thousands of actuators), an automated approach is preferable to constraint the cost and schedule. In the end we present some algorithms for the evaluation of the measurement noise; this point is particularly important since the calibration setup is typically a large facility in an industrial environment, where the noise level may be a major show-stopper.Comment: 50 pages. Final report released for the project "Development and test of a new CGH-based technique with automated calibration for future large format Adaptive-Optics Mirrors", funded under the INAF -TecnoPRIN 2010. Published by INAF - Osservatorio Astrofisico di Arcetri. ISBN: 978-88-908876-1-

Controlling the Secondary Mirror Cell of the Euro50 Project using an Inertial Measurement Unit

When building a telescope, importance does not only lie on the optical performance. Keeping the entire structure stable is also of great importance. In the case of the Euro50, the secondary mirror cell will be located some 60 m above ground level, exposed of wind speeds up to 15 m/s. This makes the stabilization of the mirror cell to a dicult problem. However, it has to be solved. The main goal of this master thesis is to develop a controller to stabilize the secondary mirror cell of the Euro50 extremely large telescope. The approach is to use an inertial measurement unit, consisting of gyros and accelermeters, for position feedback. This approach has been evaluated before, with the conclusion that no long sample times can be made due to noise in the feedback. Here, a wavefront sensor is used to create additional position feedback, thus allowing the long sample times required. Favourably, more than one controller should be derived, to give the Euro50 developers more freedom of choise. Also, the noise charateristics of the inertial measurement unit are to be investigated, to give recommendations of the performance needed. This master thesis is one of three closely related projects involving the secondary mirror cell of the Euro50 telescope. The others are Modeling and Control of a Large Deformable Mirror, and Actuator servos for Deformable Mirrors

Speckle nulling wavefront control for Palomar and Keck

We present a speckle nulling code currently being used for high contrast imaging at the Palomar and Keck telescopes. The code can operate in open and closed loop and is self-calibrating, requiring no system model and minimal hand-coded parameters. Written in a modular fashion, it is straightforward to port to different instruments. It has been used with systems operating in the optical through thermal infrared, and can deliver nearly an order of magnitude improvement in raw contrast. We will be releasing this code to the public in the near future

Limb radiance inversion radiometer

Engineering and scientific objectives of the LRIR experiment are described along with system requirements, subassemblies, and experiment operation. The mechanical, electrical, and thermal interfaces between the LRIR experiment and the Nimbus F spacecraft are defined. The protoflight model qualification and acceptance test program is summarized. Test data is presented in tables to give an overall view of each test parameter and possible trends of the performance of the LRIR experiment. Conclusions and recommendations are included

Intelligent laser cladding control system design and construction.

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