Julia Shatokhina

Julia Shatokhina
Austrian Academy of Sciences (OeAW) | ÖAW · Johann Radon Institute for Computational and Applied Mathematics (RICAM)

PhD

About

59
Publications
4,098
Reads
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335
Citations
Citations since 2017
42 Research Items
302 Citations
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
Introduction
Current projects: Wavefront reconstruction for METIS instrument on ELT; associate member at Tomography in Astronomy group, SFB Tomography across the scales
Additional affiliations
July 2018 - present
Austrian Academy of Sciences (OeAW)
Position
  • PostDoc Position
Description
  • Project "Observation-oriented astrophysics in the E-ELT era"
August 2016 - June 2018
Johannes Kepler University Linz
Position
  • Research Assistant
Description
  • Development of the mid-infrared E-ELT imager and spectrograph METIS
December 2015 - August 2016
MathConsult GmbH
Position
  • Research Assistant (part-time)
Description
  • Project ''Strand- and lay-length induced vibrations of cableways''
Education
March 2010 - November 2014
Johannes Kepler University Linz
Field of study
  • Mathematics
September 2002 - June 2007

Publications

Publications (59)
Article
We present a fast method for the wavefront reconstruction from pyramid wavefront sensor (P-WFS) measurements. The method is based on an analytical relation between pyramid and Shack-Hartmann sensor (SH-WFS) data. The algorithm consists of two steps-a transformation of the P-WFS data to SH data, followed by the application of cumulative reconstructo...
Article
Full-text available
The generation of Extremely Large Telescopes (ELTs) with mirror diameters up to 40 m has thick secondary mirror support structures (also known as spider legs), which cause difficulties in the wavefront reconstruction process. These spider legs create areas where the information of the phase is disconnected on the wavefront sensor detector, leading...
Article
Abstract. Pyramid wavefront sensors are planned to be a part of many instruments that are currently under development for the extremely large telescopes (ELT). The unprecedented scales of the upcoming ELT-era instruments are inevitably connected with serious challenges for wavefront reconstruction and control algorithms. Apart from the huge number...
Article
Full-text available
The pyramid wavefront sensor (P-WFS) has replaced the Shack-Hartmann (SH-) WFS as the sensor of choice for high-performance adaptive optics (AO) systems in astronomy. Many advantages of the P-WFS, such as its adjustable pupil sampling and superior sensitivity, are potentially of great benefit for AO-supported imaging in ophthalmology as well. Howev...
Article
Full-text available
Advanced Adaptive Optics (AO) instruments have applications in ophthalmic imaging, Free-Space Optical Communications (FSOC) and the future generation of Extremely Large Telescopes (ELTs). These AO systems are designed to perform real-time corrections of dynamic wavefront aberrations. The corrections can be performed by converting wavefront measurem...
Preprint
The pyramid wavefront sensor (P-WFS) has replaced the Shack-Hartmann (SH-) WFS as sensor of choice for high performance adaptive optics (AO) systems in astronomy because of its flexibility in pupil sampling, its dynamic range, and its improved sensitivity in closed-loop application. Usually, a P-WFS requires modulation and high precision optics tha...
Conference Paper
Full-text available
Some coronagraph masks can be turned into wave front sensing masks thanks to minor modification. For instance, one only has to divide by two the depth of the central well to convert the Roddier & Roddier coronograph into the Zernike wave front sensor (WFS). Physically, the opposition of phase in coronagrapy becomes a quadrature phase in wave front...
Conference Paper
Full-text available
Model-based matrix-free wavefront reconstruction algorithms have proven to provide highly accurate results for both Shack-Hartmann and pyramid wavefront sensors in various simulation environments (OCTOPUS, YAO, COMPASS, OOMAO). Previously, test bench as well as on-sky tests were performed with the CuReD for the Shack-Hartmann sensor providing a con...
Poster
Full-text available
Model-based matrix-free wavefront reconstruction algorithms have proven to provide highly accurate results for both Shack-Hartmann and pyramid wavefront sensors in various simulation environments (OCTOPUS, YAO, COMPASS, OOMAO). Previously, test bench as well as on-sky tests were performed with the CuReD for the Shack-Hartmann sensor providing a con...
Poster
Full-text available
Pyramid is known for years as non-linear sensor which is observed in its significantly different behaviour in K vs R band. The poster focuses on specific PWFS features (e.g., optical gain), analyses and compares its performance in two bands under variety of variable conditions: fragmented pupils, oversampling, regular vs non-Cartesian DM geometries...
Presentation
Full-text available
Description of a new Fourier based Wave Front Sensor
Article
Full-text available
The European Extremely Large Telescope (ELT) is a 39m large, ground-based optical and near- to mid-infrared telescope under construction in the Chilean Atacama desert. Operation is planned to start around the middle of the next decade. All first light instruments will come with wavefront sensing devices that allow control of the ELT’s intrinsic M4...
Presentation
Full-text available
The talk gives an introduction to reconstructors for Fourier-based wavefront sensors such as the pyramid WFS. The reconstructors are based on detailed mathematical investigations.
Article
Full-text available
In this paper, we address the inverse problem of fast, stable, and high-quality wavefront reconstruction from pyramid wavefront sensor data for adaptive optics systems on extremely large telescopes. For solving the indicated problem we apply well-known iterative mathematical algorithms, namely conjugate gradient, steepest descent, Landweber, Landwe...
Article
Full-text available
We consider the mathematical background of the wavefront sensor type that is widely used in adaptive optics systems for astronomy, microscopy, and ophthalmology. The theoretical analysis of the pyramid sensor forward operators presented in this paper is aimed at a subsequent development of fast and stable algorithms for wavefront reconstruction fro...
Presentation
Full-text available
The pyramid wavefront sensor relates the incoming wavefront and the corresponding sensor signal in a non-linear way. If the sensor is operated around a non-zero setpoint, a non-linearity induced sensitivity loss, known as optical gain effect, can result in over- or under-applied corrections when using linear wavefront reconstructors. The optical ga...
Presentation
Full-text available
We summarize our experience on the performance of several wavefront reconstruction algorithms under a variety of real-life phenomena. We compare several approaches solving the spiders problem (pupil fragmentation), and focus on illumination and modulation as parameters influencing the result. Also, we analyze the severity of the pupil fragmentatio...
Preprint
The ELT is a 39m large, ground-based optical and near- to mid-infrared telescope under construction in the Chilean Atacama desert. Operation is planned to start around the middle of the next decade. All first light instruments will come with wavefront sensing devices that allow control of the ELT's intrinsic M4 and M5 wavefront correction units, th...
Preprint
We consider the mathematical background of the wavefront sensor type that is widely used in Adaptive Optics systems for astronomy, microscopy, and ophthalmology. The theoretical analysis of the pyramid sensor forward operators presented in this paper is aimed at a subsequent development of fast and stable algorithms for wavefront reconstruction fro...
Preprint
In this paper, we address the inverse problem of fast, stable, and high-quality wavefront reconstruction from pyramid wavefront sensor data for Adaptive Optics systems on Extremely Large Telescopes. For solving the indicated problem we apply well-known iterative mathematical algorithms, namely conjugate gradient, steepest descent, Landweber, Landwe...
Preprint
In this paper, we address the inverse problem of fast, stable, and high-quality wavefront reconstruction from pyramid wavefront sensor data for Adaptive Optics systems on Extremely Large Telescopes. For solving the indicated problem we apply well-known iterative mathematical algorithms, namely conjugate gradient, steepest descent, Landweber, Landwe...
Preprint
We consider the mathematical background of the wavefront sensor type that is widely used in Adaptive Optics systems for astronomy, microscopy, and ophthalmology. The theoretical analysis of the pyramid sensor forward operators presented in this paper is aimed at a subsequent development of fast and stable algorithms for wavefront reconstruction fro...
Poster
Pyramid wavefront sensors are planned to be part of many instruments on ELT-sized telescopes. The high number of correcting elements to be controlled in real-time and the segmented pupils of the ELTs lead to unprecedented challenges posed to the control algorithms. Based on detailed studies of the pyramid sensor model, several algorithms for a sta...
Presentation
Full-text available
Pyramid wavefront sensors are planned to be included on large earthbound telescopes currently under development. These rely on real-time adaptive optics systems to compensate for atmospheric perturbations. Using our mathematical analysis of the pyramid sensor model, we present several algorithms for a high-quality and high-speed wavefront correctio...
Presentation
Full-text available
https://www.dur.ac.uk/resources/cfai/workshop2018/oberederThursday.pdf
Presentation
Full-text available
Accurate and robust wavefront reconstruction methods for pyramid sensors are in high demand since the sensors are planned to be part of many instruments currently under development for ELT-sized telescopes. The pyramid wavefront sensor relates the sought-after, incoming wavefront or deformable mirror actuator commands and the sensor measurements in...
Presentation
Full-text available
Direct piston reconstruction approaches to control segmented ELT-mirrors http://web.oapd.inaf.it/adoni/wfs2017/pdf_wfs2017/hutterer_wfs2017.pdf
Presentation
Full-text available
Overview on pyramid wavefront sensor: forward models, reconstruction algorithms, practical issues http://web.oapd.inaf.it/adoni/wfs2017/pdf_wfs2017/shatokhina_wfs2017.pdf
Article
In this paper we present two novel algorithms for wavefront reconstruction from pyramid-type wavefront sensors data. An overview of the current state-of-the-art in the application of pyramid-type wavefront sensors shows that the novel algorithms can be applied in various scientific fields such as astronomy, ophthalmology, and microscopy. Assuming a...
Poster
Full-text available
Two novel algorithms for wavefront reconstruction from pyramid sensor data: Convolution with Linearized Inverse Filter and Pyramid Fourier Transform Reconstructor
Poster
Pyramid wavefront sensors are included as baseline on many instruments under development for ELTs. We focus on wavefront reconstruction from non- modulated pyramid and roof wavefront sensor data. A detailed analytical study of the pyramid sensor lays the mathematical foundation of our reconstruction methods. The proposed algorithms are based on a s...
Conference Paper
In this poster, we compare three pyramid type sensors (the traditional 4-sided pyramid, a 3-sided prism, and 2 orthogonal 2-sided roof sensors) as well as the MVM and pCuReD reconstruction algorithms with closed loop numerical adaptive optics simulations for an xAO system for the 37m EELT.
Presentation
Full-text available
Modern big telescopes rely on real-time adaptive optics systems to image celestial objects through the turbulent sky. For the 30 m-class telescopes (named extremely large) under construction, the complexity of adaptive optics systems grows significantly. This makes the existing control algorithms too heavy from the computational point of view to be...
Conference Paper
We present a fast wavefront reconstruction algorithm developed for an extreme adaptive optics system equipped with a pyramid wavefront sensor on a 42m telescope. The method is called the Preprocessed Cumulative Reconstructor with domain decomposition (P-CuReD). The algorithm is based on the theoretical relationship between pyramid and Shack-Hartman...
Conference Paper
Full-text available
For large AO systems equipped with a pyramid wavefront sensor (WFS) the existing control algorithms (MVM, FTR) are computationally very heavy. Thus it was impossible to achieve a reconstruction in real time (e.g., on the E-ELT XAO system EPICS running at a frequency of 3 kHz). To overcome this problem, we developed a new algorithm for wavefront rec...
Conference Paper
Full-text available
For large AO systems equipped with a pyramid wavefront sensor (WFS) the existing control algorithms (MVM, FTR) are computationally very heavy to run in real time (at a frequency of 3 kHz required for the XAO system on the ELT). To overcome this problem, we developed new algorithms with highly reduced computational costs (compared to the standard me...
Conference Paper
Full-text available
In this talk we present our work done within the Austrian in-kind project “Mathematical algorithms and software for E-ELT Adaptive Optics”. In particular, we consider a problem of reconstructing in real time a wavefront from the modulated Pyramid/Roof wavefront sensor (WFS) measurements. The forward operator Q describing the WFS is singular and non...
Poster
We present our work done within the Austrian InKind project ’Mathematical algorithms and software for E-ELT Adaptive Optics’. In particular, we are concerned with eXtreme Adaptive Optics (XAO). Our aim is the development of fast algorithms for reconstructing the incoming wavefront φ from the sensor measurements s. Possible choices of sensors for th...
Poster
Full-text available
We present our work done within the Austrian InKind project ’Mathematical algorithms and software for E-ELT Adaptive Optics’. In particular, we are concerned with eXtreme Adaptive Optics (XAO). Our aim is the development of fast algorithms for reconstructing the incoming wavefront φ from the sensor measurements s. Possible choices of sensors for th...
Article
On the basis of assumption about a weakly turbulent state of the magnetospheric plasma the model of the nonlinear "black box" for prediction of its state is proposed. It is also assumed that a weakly turbulent state of the environment is caused by the influence of the solar wind velocity and southern component of the interplanetary magnetic field o...
Article
Full-text available
Several approaches to vegetation state estimation on the basis of the leaves reflectance spectra curves have been developed [1-4]. During last years has been made a large progress in the investigation of the above problem. Influences of various environmental factors on the reflectance spectral curves has been studied. The vegetation reflectance cur...
Article
We consider the problem of estimating and classifying the vegetation state. The method of reference vectors for classification of the plants reflection spectrum into several classes, depending on the concentration of chlorophyll available, is proposed. We describe a new approach for validation of satellite hyperspectral data on the basis of compari...
Article
Full-text available
We consider the problem of space weather modeling and prediction. It is suggested to utilize the nonlinear noisy black-box model to predict the Dst index. We assume the presence of a weak turbulence for the magnetosphere plasma. It is suggested to consider the solar wind parameter VBz (a product of the solar wind speed on the south magnetic field c...
Article
Full-text available
Y. Berkovich proposed the following problem: Suppose that a p-group G satisfies the following condition: if Z is a cyclic subgroup of G, then either Z≤Z(G) or Z∩Z(G)={1}. Classify all such groups. We prove that Abelian p-groups and p-groups with exponent p exhaust all regular p-groups satisfying this condition. https://ekmair.ukma.edu.ua/handle/123...

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Projects

Projects (5)
Project
Development of analytical forward models for pyramid WFS and algorithms for their stable inversion