Abstract:Modern adaptive optics (AO) systems for large telescopes require tomographic techniques to reconstruct the phase aberrations induced by the turbulent atmosphere along a line of sight to a target which is angularly separated from the guide sources that are used to sample the atmosphere. Multi-object adaptive optics (MOAO) is one such technique.Here, we present a method which uses an artificial neural network (ANN) to reconstruct the target phase given off-axis references sources. We compare our ANN method with a standard least squares type matrix multiplication method and to the learn and apply method developed for the CANARY MOAO instrument. The ANN is trained with a large range of possible turbulent layer positions and therefore does not require any input of the optical turbulence profile. It is therefore less susceptible to changing conditions than some existing methods. We also exploit the non-linear response of the ANN to make it more robust to noisy centroid measurements than other linear techniques. Assémat, E. Gendron, and F. Hammer, "The FALCON concept: multi-object adaptive optics and atmospheric tomography for integral field spectroscopy -principles and performance on an 8-m telescope," MNRAS 376, 287-312 (2007). 5. Morris, T., Hubert, Z., Myers, R., Gendron, E., Longmore, A., Rousset, G., Talbot, G., Fusco, T., Dipper, N., Vidal, F., Henry, D., Gratadour, D., Butterley, T., Chemla, F., Guzman, D., Laporte, P., Younger, E., Kellerer, A., Harrison, M., Marteaud, M., Geng, D., Basden, A., Guesalaga, A., Dunlop, C., Todd, S., Robert, C., Dee, K., Dickson, C., Vedrenne, N., Greenaway, A., Stobie, B., Dalgarno, H., and Skvarc, J., "CANARY: The NGS/LGS MOAO demonstrator for EAGLE," 1st AO4ELT conference p. 08003 (2010). 2527-2538 (2001). 18. J. W. Wild, E. J. Kibblewhite, and R. Vuilleumier, "Sparse matrix wave-front estimators for adaptive-optics systems for large ground-based telescopes," Opt. Lett. 20(9), 955 -957 (1995). 19. E. Thiébaut and M. Tallon, "Fast minimum variance wavefront reconstruction for extremely large telescopes," J.

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AOtools is a Python package which is open-source and aimed at providing tools for adaptive optics users and researchers. We present version 1.0 which contains tools for adaptive optics processing, including analysing data in the pupil plane, images and point spread functions in the focal plane, wavefront sensors, modelling of atmospheric turbulence, physical optical propagation of wavefronts, and conversion between frequently used adaptive optics and astronomical units. The main drivers behind AOtools is that it should be easy to install and use. To achieve this the project features extensive documentation, automated unit testing and is registered on the Python Package Index. AOtools is under continuous active development to expand the features available and we encourage everyone involved in adaptive optics to become involved and contribute to the project.

Vibrations are detrimental to the performance of modern adaptive optics (AO) systems. In this paper, we describe new methods tested to mitigate the vibrations encountered in some of the instruments of the Gemini South telescope. By implementing a spectral analysis of the slope measurements from several wavefront sensors and an imager, we can determine the frequencies and magnitude of these vibrations. We found a persistent vibration at 55 Hz with others occurring occasionally at 14 and 100 Hz. Two types of AO controllers were designed and implemented, Kalman and H∞, in the multiconjugate AO tip-tilt loop. The first results show a similar performance for these advanced controllers and a clear improvement in vibration rejection and overall performance over the classical integrator scheme. It is shown that the reduction in the standard deviation of the residual slopes (as measured by wavefront sensors) is highly dependent on turbulence, wind speed, and vibration conditions, ranging--in terms of slopes RMS value--from an almost negligible reduction for high speed wind to a factor of 5 for a combination of low wind and strong vibrations.

An interface for software that creates a natural environment for engineering graphics students to improve their spatial reasoning and 3D visualization skills is described. The skills of interest involve spatial transformations and rotations, specifically those skills that engineers use to reason about 3D objects based on 2D representations. The software uses an intuitive and interactive interface allowing direet manipulation of objects.Animation capability is provided to demonstrate the relationship between arbitrary positions of an object and standard orthographic views. A second skill of interest requires visualization of a cuttingplane intersection of an object. An interface is developed which allows intuitive positioning of the cutting-plane utilizing the metaphor of a "pool of water" in which the object is partially submerged. The surface of the water represents the cutting plane. Adjustment of the pool depth combined with direct manipulation of the object provides for arbitrary positioning of the cutting-plane. Subjective evaluation of the software thus far indicates that students enjoy using it and find it helpful. A formal testing plan to objectively evaluate the software and interface design is underway.