Abstract

Shack-Hartmann (S-H) phasing of segmented telescopes is based upon a physical optics generalization of the geometrical optics Shack-Hartmann test, in which each S-H lenslet straddles an intersegment edge. For the extremely large segmented telescopes currently in the design stages, one is led naturally to very large pupil demagnifications for the S-H phasing cameras. This in turn implies rather small Fresnel numbers F for the lenslets; the nominal design for the Thirty Meter Telescope calls for F=0.6. For such small Fresnel numbers, it may be possible to eliminate the lenslets entirely, replacing them with a simple mask containing a sparse array of clear subapertures and thereby also eliminating a number of manufacturing problems and experimental complications associated with lenslets. We present laboratory results that demonstrate the validity of this approach.

© 2011 Optical Society of America

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References

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  1. G. A. Chanan, M. Troy, F. G. Dekens, S. Michaels, J. Nelson, T. Mast, and D. Kirkman, “Phasing the mirror segments of the Keck telescopes: the broadband phasing algorithm,” Appl. Opt. 37, 140–155 (1998).
    [CrossRef]
  2. G. A. Chanan, C. Ohara, and M. Troy, “Phasing the mirror segments of the Keck telescopes: the narrowband phasing algorithm,” Appl. Opt. 39, 4706–4714 (2000).
    [CrossRef]
  3. G. A. Chanan, “Design of the Keck Observatory alignment camera,” Proc. SPIE 1036, 59–70 (1988).
  4. J. Nelson and G. H. Sanders, “TMT status report,” Proc. SPIE 6267, 626728 (2006).
    [CrossRef]
  5. R. Gilmozzi and J. Spyromilio, “The 42 m European ELT: Status,” Proc. SPIE 7012, 701219 (2008).
    [CrossRef]
  6. F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
    [CrossRef]
  7. I. Surdej, N. Yaitskova, and F. Gonté, “On-sky performance of the Zernike phase contrast sensor for the phasing of segmented telescopes,” Appl. Opt. 49, 4052–4062 (2010).
    [CrossRef] [PubMed]
  8. F. Gonté, R. Mazzoleni, I. Surdej, and L. Noethe, “On-sky performance of an optical phasing sensor based on a cylindrical lenslet array for segmented telescopes,” Appl. Opt. 50, 1660–1667 (2011).
    [CrossRef] [PubMed]
  9. F. Gonté, C. Dupuy, B. Luong, C. Frank, R. Brast, and B. Sedghi, “Active hexagonally segmented mirror to investigate new optical phasing technologies for segmented telescopes,” Appl. Opt. 48, 6392–6399 (2009).
    [CrossRef] [PubMed]
  10. R. Wilhelm, B. Luong, A. Courteville, S. Estival, F. Gonté, and N. Schuhler, “Dual-wavelength low-coherence instantaneous phase-shifting interferometer to measure the shape of a segmented mirror with subnanometer precision,” Appl. Opt. 47, 5473–5491 (2008).
    [CrossRef] [PubMed]
  11. J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
    [CrossRef]
  12. R. Cohen, T. Mast, and J. Nelson, “Performance of the W. M. Keck telescope active mirror control system,” Proc. SPIE 2199, 105–116 (1994).
    [CrossRef]
  13. M. Troy and G. Chanan, “Diffraction effects from giant segmented-mirror telescopes,” Appl. Opt. 42, 3745–3753(2003).
    [CrossRef] [PubMed]

2011 (1)

2010 (1)

2009 (1)

2008 (2)

2006 (1)

J. Nelson and G. H. Sanders, “TMT status report,” Proc. SPIE 6267, 626728 (2006).
[CrossRef]

2004 (2)

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

2003 (1)

2000 (1)

1998 (1)

1994 (1)

R. Cohen, T. Mast, and J. Nelson, “Performance of the W. M. Keck telescope active mirror control system,” Proc. SPIE 2199, 105–116 (1994).
[CrossRef]

1988 (1)

G. A. Chanan, “Design of the Keck Observatory alignment camera,” Proc. SPIE 1036, 59–70 (1988).

Brast, R.

F. Gonté, C. Dupuy, B. Luong, C. Frank, R. Brast, and B. Sedghi, “Active hexagonally segmented mirror to investigate new optical phasing technologies for segmented telescopes,” Appl. Opt. 48, 6392–6399 (2009).
[CrossRef] [PubMed]

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Chanan, G.

Chanan, G. A.

Cohen, R.

R. Cohen, T. Mast, and J. Nelson, “Performance of the W. M. Keck telescope active mirror control system,” Proc. SPIE 2199, 105–116 (1994).
[CrossRef]

Courteville, A.

R. Wilhelm, B. Luong, A. Courteville, S. Estival, F. Gonté, and N. Schuhler, “Dual-wavelength low-coherence instantaneous phase-shifting interferometer to measure the shape of a segmented mirror with subnanometer precision,” Appl. Opt. 47, 5473–5491 (2008).
[CrossRef] [PubMed]

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Dekens, F. G.

Delabre, B.

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Devaney, N.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Dierickx, P.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Dohlen, K.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Dupuy, C.

Esposito, S.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Estival, S.

Ferrari, M.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Frank, C.

Franza, F.

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Gilmozzi, R.

R. Gilmozzi and J. Spyromilio, “The 42 m European ELT: Status,” Proc. SPIE 7012, 701219 (2008).
[CrossRef]

Gonté, F.

Gonté, F. Y.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Jacob, S.

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Karban, R.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Kirkman, D.

Kolb, J.

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Luong, B.

Marchetti, E.

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Mast, T.

Mazzoleni, R.

Michaels, S.

Montoya, L.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Nelson, J.

J. Nelson and G. H. Sanders, “TMT status report,” Proc. SPIE 6267, 626728 (2006).
[CrossRef]

G. A. Chanan, M. Troy, F. G. Dekens, S. Michaels, J. Nelson, T. Mast, and D. Kirkman, “Phasing the mirror segments of the Keck telescopes: the broadband phasing algorithm,” Appl. Opt. 37, 140–155 (1998).
[CrossRef]

R. Cohen, T. Mast, and J. Nelson, “Performance of the W. M. Keck telescope active mirror control system,” Proc. SPIE 2199, 105–116 (1994).
[CrossRef]

Noethe, L.

Ohara, C.

Reversat, F.

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Sanders, G. H.

J. Nelson and G. H. Sanders, “TMT status report,” Proc. SPIE 6267, 626728 (2006).
[CrossRef]

Schuhler, N.

Schumacher, A.

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Sedghi, B.

Spyromilio, J.

R. Gilmozzi and J. Spyromilio, “The 42 m European ELT: Status,” Proc. SPIE 7012, 701219 (2008).
[CrossRef]

Surdej, I.

Tisserand, S.

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

Troy, M.

Wilhelm, R.

Yaitskova, N.

I. Surdej, N. Yaitskova, and F. Gonté, “On-sky performance of the Zernike phase contrast sensor for the phasing of segmented telescopes,” Appl. Opt. 49, 4052–4062 (2010).
[CrossRef] [PubMed]

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

Appl. Opt. (7)

Proc. SPIE (6)

G. A. Chanan, “Design of the Keck Observatory alignment camera,” Proc. SPIE 1036, 59–70 (1988).

J. Nelson and G. H. Sanders, “TMT status report,” Proc. SPIE 6267, 626728 (2006).
[CrossRef]

R. Gilmozzi and J. Spyromilio, “The 42 m European ELT: Status,” Proc. SPIE 7012, 701219 (2008).
[CrossRef]

F. Y. Gonté, N. Yaitskova, P. Dierickx, R. Karban, A. Courteville, A. Schumacher, N. Devaney, S. Esposito, K. Dohlen, M. Ferrari, and L. Montoya, “APE: a breadboard to evaluate new phasing technologies for a future European giant optical telescope,” Proc. SPIE 5489, 1184–1191 (2004).
[CrossRef]

J. Kolb, E. Marchetti, S. Tisserand, F. Franza, B. Delabre, F. Gonté, R. Brast, S. Jacob, and F. Reversat, “MAPS, a turbulence simulator for MCAO,” Proc. SPIE 5490, 794–804(2004).
[CrossRef]

R. Cohen, T. Mast, and J. Nelson, “Performance of the W. M. Keck telescope active mirror control system,” Proc. SPIE 2199, 105–116 (1994).
[CrossRef]

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Figures (10)

Fig. 1
Fig. 1

Fresnel diffraction patterns for Fresnel number 0.625 (left) and 1.32 (right) for a semicircular subaperture. The aperture radius is 60 mm and the wavelength is 800 nm . The Fraunhofer pattern is shown on both plots for comparison. While the pattern is centered on the center of the circle for Fraunhofer diffraction, in the Fresnel case it is shifted toward the illuminated half of the circle, the shift increasing with Fresnel number.

Fig. 2
Fig. 2

Narrowband Fresnel diffraction patterns for Fresnel numbers 0.625 (left column) and 1.32 (right column) for various edge step values. Fraunhofer patterns are shown for comparison. At F = 0.625 the patterns are simple and there is little difference between Fresnel and Fraunhofer diffraction; at F = 1.32 . the differences are substantial and the Fresnel patterns are complicated.

Fig. 3
Fig. 3

Broadband Fresnel diffraction patterns for Fresnel number 0.625 (left) and 1.32 (right) for an infinite edge step (incoherent illumination). The corresponding Fraunhofer pattern is shown for comparison. As for the narrowband case, there is little difference between Fresnel and Fraunhofer diffraction at F = 0.625 , but the difference is substantial for F = 1.32 .

Fig. 4
Fig. 4

Segmentation pattern of the 61-segment ASM. The shadings indicate the assignment of the three segment colors. By moving segments of the same color in concert, all intersegment edges can be swept through a given range of values in an efficient manner. (The color scheme can readily be extended to arbitrary segmentation patterns.)

Fig. 5
Fig. 5

Left panel: Full CCD image of the laboratory Fresnel phasing experiment for a “test pattern” in which the step size at every intersegment edge is either 0 or λ / 8 . Right panel: Detail of the same CCD image.

Fig. 6
Fig. 6

Results of the closed-loop converge tests. These tests indicate a repeatability of the measurements of about 3 nm . For the measurement accuracy see the discussion of open-loop experiments.

Fig. 7
Fig. 7

Open-loop narrowband measurements for chrome-on-glass masks at 650 nm (left) and 900 nm (right) without simulated turbulence.

Fig. 8
Fig. 8

Open-loop narrowband measurements for laser-drilled Kapton masks at 650 nm with simulated turbulence on two different dates. The sinusoidal residuals evident in the right hand plot are believed to result from mask-pupil registration errors.

Fig. 9
Fig. 9

Typical Keck narrowband phasing results at 651 nm .

Fig. 10
Fig. 10

Broadband phasing results for the laboratory experiment described in the text. The coherence parameter traces out the expected quasi-Gaussian curve. The small scale structure in the data and the error bars is exaggerated because the spacing of the data points was close to a quarter wave.

Tables (1)

Tables Icon

Table 1 Summary of the Seven Narrowband Laboratory Fresnel Phasing Runs from the Current Investigation with Two Typical Fraunhofer Phasing Runs from the Keck Telescope Shown for Comparison a

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

F = a 2 λ r .
exp { i k r ρ · ρ } exp { i k r [ ρ · ρ ρ 2 2 + ( ρ · ρ ) 2 2 r 2 ] }

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