Abstract

We present the results of the co-phasing closed loop performed with a pyramid wavefront sensor for what we believe to be the first time in the presence of emulated atmospheric disturbance. The performance of the co-phasing loop is significantly improved by applying two spatial filters in the sensor signal space. The first is a zonal filter applied to the interaction matrix before the computation of the reconstructor; the second is a modal filter applied to the sensor signals before the correction command computation. The presented laboratory results demonstrate that, applying both filters, the time requested to average out the atmospheric disturbance in each loop step is reduced by 2 orders of magnitude, improving the loop stability and accuracy.

© 2007 Optical Society of America

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References

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  1. G. Chanan, M. Troy, I. Crossfield, J. Nelson, and T. Mast, Proc. SPIE 6267, 62672V (2006).
    [Crossref]
  2. S. Esposito and N. Devaney, in Beyond Conventional Adaptive Optics, Vol. 58 of ESO Conference and Workshop Proceedings (European Southern Observatory, 2001), pp. 161-166.
  3. That is because there will be tens of segments on the diameter of the ELT primary mirror and the signal is localized on the segments edges.
  4. S. Esposito and A. Riccardi, Astron. Astrophys. 369, L9 (2001).
    [Crossref]
  5. N. Yaitskova, F. Gonte, F. Derie, L. Noethe, I. Surdej, R. Karban, K. Dohlen, M. Langlois, S. Esposito, E. Pinna, M. Reyes, L. Montoya, and D. Terrett, Proc. SPIE 626762672Z (2006).
    [Crossref]
  6. S. Esposito, O. Feeney, and A. Riccardi, Proc. SPIE 4007, 416 (2000).
    [Crossref]
  7. S. Esposito, E. Pinna, A. Puglisi, A. Tozzi, and P. Stefanini, Opt. Lett. 30, 2572 (2005).
    [Crossref] [PubMed]

2006 (2)

G. Chanan, M. Troy, I. Crossfield, J. Nelson, and T. Mast, Proc. SPIE 6267, 62672V (2006).
[Crossref]

N. Yaitskova, F. Gonte, F. Derie, L. Noethe, I. Surdej, R. Karban, K. Dohlen, M. Langlois, S. Esposito, E. Pinna, M. Reyes, L. Montoya, and D. Terrett, Proc. SPIE 626762672Z (2006).
[Crossref]

2005 (1)

2001 (1)

S. Esposito and A. Riccardi, Astron. Astrophys. 369, L9 (2001).
[Crossref]

2000 (1)

S. Esposito, O. Feeney, and A. Riccardi, Proc. SPIE 4007, 416 (2000).
[Crossref]

Astron. Astrophys. (1)

S. Esposito and A. Riccardi, Astron. Astrophys. 369, L9 (2001).
[Crossref]

Opt. Lett. (1)

Proc. SPIE (3)

N. Yaitskova, F. Gonte, F. Derie, L. Noethe, I. Surdej, R. Karban, K. Dohlen, M. Langlois, S. Esposito, E. Pinna, M. Reyes, L. Montoya, and D. Terrett, Proc. SPIE 626762672Z (2006).
[Crossref]

S. Esposito, O. Feeney, and A. Riccardi, Proc. SPIE 4007, 416 (2000).
[Crossref]

G. Chanan, M. Troy, I. Crossfield, J. Nelson, and T. Mast, Proc. SPIE 6267, 62672V (2006).
[Crossref]

Other (2)

S. Esposito and N. Devaney, in Beyond Conventional Adaptive Optics, Vol. 58 of ESO Conference and Workshop Proceedings (European Southern Observatory, 2001), pp. 161-166.

That is because there will be tens of segments on the diameter of the ELT primary mirror and the signal is localized on the segments edges.

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Figures (4)

Fig. 1
Fig. 1

Example of a mask applied in IMM (top left). PYPS signal ( s x ) in arbitrary units obtained when a piston is applied to a central MEMS segment with (top right) and without (top center) the IMM applied. The same signals are represented in a reduced signal range (bottom).

Fig. 2
Fig. 2

Piston error rms of the 50 controlled segments as function of the closed-loop iterations for T e = 72 s and n z = 0 and 3 in the cases with and without IMM. The single segment error is computed as the difference between the MEMS iteration command and the referenced one.

Fig. 3
Fig. 3

LOR test in closed loop. The plots, as in Fig. 2, represent the residual pistons versus the loop iterations in several filtering and integration conditions. IMM is applied in all the loops.

Fig. 4
Fig. 4

Comparison of the performances of the closed loop in all the T e and n Z conditions experimented. The vertical axis shows the residual piston values (rms on the 50 actuated segments) averaged on the iterations 20 50 .

Equations (1)

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s x z r = [ I P z ( P z T P z ) + P z T ] ( s x s x 0 ) ,

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