Piston and tilt interferometry for segmented wavefront sensing

Deprez, Maxime; Bellanger, Cindy; Lombard, Laurent; Wattellier, Benoît; Primot, Jérôme

doi:10.1364/ol.41.001078

Cited by 25 publications

(15 citation statements)

References 14 publications

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“…The PISTIL interferometer belongs to the family of lateral shearing interferometry. [18][19][20][21] Its working principle 16 (depicted in Figure 2) is based on two-wave interference of wavefront replicas propagating from two neighboring segmented elements. A collimated beams collection from the segmented surface enters the system passing through the hole mask.…”

Section: Principle Of Pistil Interferometrymentioning

confidence: 99%

“…New cophasing means have been developed, such as broadband phasing, 13 and phase masks. 14,15 The PISTIL interferometer 16,17 is a Piston and Tip/Tilt segmented wavefront analyzer developed to meet the metrology need on the new coherent combination laser benches and possibly others segmented surfaces. Its development, initiated recently, has led to promising results in terms of the measurement accuracy, repeatability and resolution.…”

Section: Introductionmentioning

confidence: 99%

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Segmented wavefront metrology using multicolor PISTIL interferometry

Rouzé

Bellanger

Lanzoni

et al. 2020

Optics and Photonics for Advanced Dimensional Metrology

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PISTIL (Piston and Tilt) is a recent interferometric system that computes the absolute piston and tip/tilt map of a segmented wavefront. Its high precision makes it usable as a metrology tool for wavefront sensing of coherently-combined laser arrays for example. This interferometer needs to correctly address high dynamic piston sensing, while dealing with fringes wrapping that leads to ambiguous phase estimations. We derived a mathematical combination for two measurements at different wavelengths and did a technical demonstration of it, using a IRIS-AO PTT111 Deformable Mirror as a segmented wavefront generator. We have verified that the loss of accuracy is slightly increased for a larger piston compared to a previous study, and we got a standard error of λ/160 with a Peak-to-valley of λ/50. This technique could be extended to a broader spectrum.

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Section: Principle Of Pistil Interferometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Segmented wavefront metrology using multicolor PISTIL interferometry

Rouzé

Bellanger

Lanzoni

et al. 2020

Optics and Photonics for Advanced Dimensional Metrology

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“…We present a new Two-Wavelength PISTIL (Two Wavelength PISton and TILt) interferometry concept. It is a member of lateral-shearing interferometers family and evolution of the recent PISTIL concept [12]. This phase analyzer is very handy because it consists of few optical elements easily packable and does not require an external reference wavefront.…”

Section: Introductionmentioning

confidence: 99%

High-dynamic range segmented mirror metrology by two-wavelength PISTIL interferometry: demonstration and performance

Rouzé¹,

Primot²,

Lanzoni³

et al. 2020

Opt. Express

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The PISTIL interferometry has been recently developed for the wavefront sensing of phase delays (pistons) and tilts of segmented surfaces, used in many domains such as astronomy, high-power lasers or ophthalmology. In this paper, we propose a two-wavelength version of this interferometer developed to bypass the dynamic range limitation of the ambiguous 2π phase wrapping. Principle of the technique is presented, along with experimental results obtained with a demonstration deformable mirror PTT-111 from Iris AO. Above wavelength pistons are measured with a precision and accuracy below λ/100, making the two-wavelength PISTIL interferometry a high-dynamic range technique. To prove these performances, we successfully compare the results in terms of precision and accuracy with those of a reference phase-shifting Interferometer, from a blind experimentation.

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“…(2) Pupil plane techniques, which include modified Shack-Hartmann sensing, the pyramid sensor, and the Mach-Zehnder Interferometer. (3) Intermediate plane techniques, which generally refer to curvature sensing (CS) [1]- [6].…”

Section: Introductionmentioning

confidence: 99%

Extending Capture Range for Piston Error in Segmented Primary Mirror Telescopes Based on Wavelet Support Vector Machine With Improved Particle Swarm Optimization

et al. 2020

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In the co-phasing techniques applied to the segmented telescope, a Shack-Hartmann wavefront sensor cannot accurately detect the piston error of the segment. Although the phase diversity (PD) algorithm can detect the piston error of each segment, it fails to reconstruct the wavefront quickly, and its dynamic range is small. Other technologies, such as prisms or micro-lens arrays, will significantly increase the complexity and construction cost of the optical system. Moreover, they may also introduce noncommon path errors. In this study, we propose an approach to address this challenging problem via curvature sensing. This method uses multi-wavelength to eliminate the influence of 2π ambiguity and improve the capture range of co-phasing detection. However, curvature sensing is easily influenced by atmospheric seeing. We propose a wavelet support vector machine optimized via particle swarm optimization (PSO-WSVM) method to deal with this problem, and to improve the application scope of curvature sensing. We reshape SVM with a wavelet kernel function, and improve the PSO algorithm. We train the SVM to build a prediction model to distinguish the piston error range of each pair of adjacent segments and surpass 2π ambiguity. First, we obtain defocused images by means of the convolution technique. Second, we propose a prediction model based on SVM. We select the correlation coefficient between the sampling signal and the template signal at different wavelengths as the input vector, and we choose a wavelet basis function as the kernel function of SVM. Third, we improve the PSO algorithm with the exponential decreasing inertia weight (EDIW) to tune the parameters of SVM. Finally, we perform a simulation experiment on a real optical system model based on the Keck telescope. The results indicate that the performance of this method is better than that of other state-of-the-art SVM-based classifiers, and it works rapidly during the observation.

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Piston and tilt interferometry for segmented wavefront sensing

Cited by 25 publications

References 14 publications

Segmented wavefront metrology using multicolor PISTIL interferometry

Segmented wavefront metrology using multicolor PISTIL interferometry

High-dynamic range segmented mirror metrology by two-wavelength PISTIL interferometry: demonstration and performance

Extending Capture Range for Piston Error in Segmented Primary Mirror Telescopes Based on Wavelet Support Vector Machine With Improved Particle Swarm Optimization

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