Abstract

We present the results from a laboratory multiconjugate adaptive optics experiment. The experiment is differentiated from other published work in that it has a programmable deterministic turbulence generator and an output science camera. The turbulence was generated using a dual layer turbulence emulator, and then corrected using an AO system with 2 wavefront correctors and a Shack-Hartman wavefront sensor, which processed information from five artificial guide stars. We report our results and also describe some of the problems.

© 2004 Optical Society of America

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Adaptive Optics Associates Inc (1)

Adaptive Optics Associates Inc. <a href="http://www.aoainc.com">http://www.aoainc.com</a>

Astron. Astrophys (1)

E. Diolaiti, R. Ragazzoni, and M. Tordi. �??Closed loop system performance of a layer-oriented multi-conjugate adaptive optics system,�?? Astron. Astrophys. 372, 710-718 (2001)
[CrossRef]

Astron. Notes (1)

B. Soltau, Th. Berkefeld, O. von der Lühe, F. Wöger, Th. Schelenz, �??Adaptive optics and multi-conjugate adaptive optics with the VTT,�?? Astron. Notes 323, 236-240 (2001)
[CrossRef]

ESO Conference and Workshop Proceedings (2)

I. Sharf, K. Bell, D. Crampton, J. Fitzsimmons, G. Herriot, L. Jolissaint, B. Lee, H. Richardson, D. van der Kamp, & J.P. Veran, �??Design of the dual conjugate adaptive optics test-bed,�?? Beyond Conventional Adaptive Optics. Ed. E. Vernet, R. Ragazzoni, S. Esposito, and N. Hubin. ESO Conference and Workshop Proceedings, 58, 383-389 (2002)

Gordon D. Love, Paul Clark, Colin N. Dunlop, Thu-Lan Kelly, Maud Langlois, Richard M. Myers and Ray M. Sharples. �??Emulating Multiconjugate Turbulence,�?? Beyond Conventional adaptive optics. Ed. E. Vernet, R. Ragazzoni, S. Esposito, and N. Hubin. ESO Conference and Workshop Proceedings, 58, 313-319 (2002).

J. Opt. Soc. Am. A (4)

Nature (1)

R. Ragazzoni.�?? Adaptive-optics corrections available for the whole sky,�?? Nature, Vol. 403, 6765, 54-56 (2000).
[CrossRef]

Opt. Express (4)

Thu-Lan Kelly, David F. Buscher, Paul Clark, Colin N. Dunlop, Gordon D. Love, Richard M. Myers, Ray M. Sharples and Andrew Zadrozny. �??Dual-conjugate wavefront generation for adaptive optics,�?? Opt. Express 7, 368-374 (2000), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-7-11-368">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-7-11-368</a>
[CrossRef] [PubMed]

P. A. Knutsson and M. Owner-Petersen, �??Emulation of dual-conjugate adaptive optics on an 8-m class telescope,�?? Opt. Express 11, 2231-2237 (2003), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2231">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2231</a>.
[CrossRef] [PubMed]

S. P. Kotova, M. Yu. Kvashnin, M. A. Rakhmatulin and O. A. Zayakin,, I. R. Guralnik and N. A. Klimov, P. Clark, G. D. Love, A. F. Naumov and C. D. Saunter, M. Yu. Loktev and G. V. Vdovin, L. V. Toporkova. �??Modal liquid crystal wavefront corrector,�?? Opt. Express 10, 1258-1272 (2002) <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-10-22-1258">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-10-22-1258</a>
[CrossRef] [PubMed]

S.R. Restaino, D. Dayton, S. Browne, J. Gonglewski, J. Baker, S. Rogers, S. McDermott, J. Gallegos and M. Shilko, �??On the use of dual-frequency nematic material for adaptive optics systems: first results of a closed-loop experiment,�?? Opt. Express 6, 2-6 (2000). <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-4-9-344">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-4-9-344</a>
[CrossRef] [PubMed]

Opt. Lett. (2)

Proc. SPIE (2)

B. Wallace, C. Bradley, H. Richardson, J. Kennedy, O. Keskin, P. Hampton, D. Robertson, L. Jolissaint, A. Hilton, �??Dual Conjugate adaptive optics testbed: progress report,�?? Proc. SPIE, 5169, 255-261 (2003).
[CrossRef]

Th. Berkefeld, B. Soltau, O. von der Lühe, �??Multi-conjugate adaptive optics at the Vacuum Tower Telescope, Tenerife,�?? Proc. SPIE 4839, 544-553 (2002).

Quorum Technologies Inc. (1)

Quorum Technologies Inc. <a href="http://www.quorumtechnologies.com/">http://www.quorumtechnologies.com/</a>

Santa Barbara Instrument Group (1)

Santa Barbara Instrument Group. <a href="http://www.sbig.com">http://www.sbig.com</a>

SPIE???s Meeting (2)

M.Langlois, G. Moretto, T. Rimmele, �??First Multiconjugate adaptive optics system at the Dun Solar Telescope,�?? to presented at the Astronomical Telescopes and Instrumentation SPIE�??s Meeting, Glasgow, Scotland (2004).

G. Moretto, M. Langlois, T. Rimmele, S. Hegwer. �?? Optical Setup and Design for a Solar Multi Conjugate Adaptive Optics Experimentation at Dunn Solar Telescope/NSO,�?? to presented at the Astronomical Telescopes and Instrumentation SPIE�??s Meeting, Glasgow, Scotland (2004)

Other (1)

Beyond Conventional adaptive optics. Ed. E. Vernet, R. Ragazzoni, S. Esposito, and N. Hubin. ESO Conference and Workshop Proceedings, 58 (2002)

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Figures (7)

Fig. 1.
Fig. 1.

Dual conjugate AO system optical layout. LC is for the modal liquid crystal wavefront correctors, OAP is for off-axis parabola, SLM is for spatial light modulators based on ferroelectric liquid crystal, and WFS is for Shack-Hartman wavefront sensor.

Fig. 2.
Fig. 2.

Turbulence generator optical layout (top) and photograph of the actual system (bottom).

Fig. 3.
Fig. 3.

(Left) Pupil footprints for the upper layer and ground layer conjugated LC correctors assuming a maximum guide star separation of 2 arcminutes and 5km altitude for the upper turbulence layer. (Right) LC’s-WFS geometry. There are 6×6 subapertures across the pupil, which corresponds to 5×5 LC’s actuators.

Fig. 4.
Fig. 4.

Results of reducing static internal optical aberrations (without any induced turbulence) using an image quality metric and a simple algorithm based on optimizing the images quality metric. The left hand column shows the uncorrected image for each of the 5 guide stars (central star is in the middle). The center column shows how the image quality metric changed with iteration number. The ordinate shows iteration number and the coordinate is the image metric. The right hand column shows the image after correction.

Fig. 5.
Fig. 5.

Dual corrector and five guide stars interaction matrix built by measuring the centroid motion for a sequential set of actuator pokes. The matrix inversion was performed using singular value decomposition. The matrix is broken down into 5×2 subarrays, corresponding to the 5 guide stars (indicated by the filled circles above) and the 2 wavefront correctors. The color scale has is in units of Shack Hartmann spot displacement (pixels).

Fig. 6.
Fig. 6.

Single contact pokes recovery on lower (right) and upper (left) LC’s. The left hand figure shows the magnitude of the signals being sent to each actuator in the LC versus time (increasing time is in the downward direction) when closing the loop. The two columns represent the lower LC and upper LC vectors. Any arbitrary pokes are self-corrected with minimal cross coupling between actuators and correctors. The quality of the corresponding images also so improves with time as shown on the right side of each graph, although just poking one actuator to begin with does not seriously degrade the image. It can be seen that (at the top of the figure) all the actuator signals are zero apart from the one which is poked. The system self-recovers although some crosstalk into other channels can be seen.

Fig. 7.
Fig. 7.

Closed loop results using the full MCAO system. The data (coordinate) consists of the sum of the spot displacements for each of the guide stars (represented in various colors) from the wavefront sensor as a measure of the degree of correction. The ordinate represents the iteration number in closed loop. The plots show the results achieved in single conjugate mode (left), and in dual conjugate mode (right). The turbulence had a strength of D/r0=16 on the upper layer only. The orange curve is for the central guide star, which was used for guiding in single conjugate mode. It can be seen that in this star is partially corrected whilst the spot motion for the other stars actually increases. In dual conjugate mode (right) the spot displacement for all the stars decreases.

Tables (1)

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Table 1. Summary of the components of the MCAO system.

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