Active Phasing Experiment: preliminary results and prospects

Gonté, Frederic; Araujo, Constanza; Bourtembourg, Reynald; Brast, R.; Dérie, F.; Duhoux, Philippe; Dupuy, Christophe; Frank, Christoph; Karban, Robert; Mazzoleni, Ruben; Noethe, L.; Surdej, Isabelle; Yaitskova, Natalia; Wilhelm, Rainer; Luong, Bruno; Pinna, Enrico; Chueca, S.; Vigan, A.

doi:10.1117/12.790342

Cited by 16 publications

(8 citation statements)

References 8 publications

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“…Finally, we should say that a sensor prototype -the Pyramid Phasing Sensor (PYPS) 10 -is currently being tested at ESO within the framework of the Active Phase Experiment (APE). 11,12 Although there is only one segmented mirror in the APE bench, it will be possible to place additional masks on the optical train to simulate the presence of an additional segmentation. Of course, no double-segmentation control can be fully tested in this way.…”

Section: Conclusion and Further Workmentioning

confidence: 99%

Double segmentation control with a single phasing sensor

et al. 2008

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The design of the future Extremely Large Telescopes (ELTs) is currently under way. The presence of two segmented mirrors in the optical train has been considered to be of high risk due to the additional challenge of phasing and aligning a telescope having two segmented mirrors. Nevertheless this double segmentation could be a feature of the E-ELT where the optical train will contain a segmented primary and possibly a segmented M4. In this paper we will present some preliminary studies based on numerical simulations demonstrating that with the pyramid wavefront sensor it is possible to control piston, tip, and tilt errors of two segmented mirrors in the same optical train simultaneously.

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Section: Conclusion and Further Workmentioning

confidence: 99%

Double segmentation control with a single phasing sensor

et al. 2008

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“…This may be done either with capacitive or inductive discrete edge sensors as in segmented primary mirrors [16,17], or with various optical sensors [18][19][20] that give a more or less averaged measure of the phasing error along the segment edge (see Fig. 3).…”

Section: Control Strategymentioning

confidence: 99%

Segmented bimorph mirrors for adaptive optics: morphing strategy

et al. 2014

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This paper discusses the concept of a light weight segmented bimorph mirror for adaptive optics. It focuses on the morphing strategy and addresses the ill-conditioning of the Jacobian of the segments, which are partly outside the optical pupil. Two options are discussed, one based on truncating the singular values and one called damped least squares, which minimizes a combined measure of the sensor error and the voltage vector. A comparison of various configurations of segmented mirrors was conducted; it is shown that segmentation sharply increases the natural frequency of the system with limited deterioration of the image quality.

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“…Several types of phasing sensors have been validated on sky using 10 m-class telescopes, such as the Shack-Hartmann [11][12][13], the Pyramid [13] and the Zernike phasing sensors [13][14][15]. These sensors provide comparable performances, reaching about 20 nm rms piston error (wavefront) in closed-loop for a star as faint as 18th magnitude, reaching a piston error as low as 6 nm rms for bright stars.…”

Section: Introductionmentioning

confidence: 99%

Measuring the cophasing state of a segmented mirror with a wavelength sweep and a Zernike phase contrast sensor

Cheffot¹,

Vigan²,

Lévêque³

et al. 2020

Opt. Express

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The demand for higher resolution telescopes leads to segmented primary mirrors which need to be phased for operation. A phasing sensor applying a wavelength sweep technique provides a large capture range without modulating the position of individual mirror segments. This technique offers the potential to monitor the phasing state of a segmented telescope in parallel to the science observations. We evaluate the performance of the wavelength sweep technique using a Zernike phase contrast sensor for coarse phasing. Tests results on a dedicated bench show 112 nm rms precision. With the help of a simulation, we explain a known error of the method and we suggest ways for improvements.

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Active Phasing Experiment: preliminary results and prospects

Cited by 16 publications

References 8 publications

Double segmentation control with a single phasing sensor

Double segmentation control with a single phasing sensor

Segmented bimorph mirrors for adaptive optics: morphing strategy

Measuring the cophasing state of a segmented mirror with a wavelength sweep and a Zernike phase contrast sensor

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