Active alignment of space astronomical telescopes by matching arbitrary multi-field stellar image features

Bai, Xiaoquan; Ju, Guohao; Xu, Boqian; Gao, Yan; Zhang, Chunyue; Wang, Shuaihui; Ma, Hao; Xu, Shuyan

doi:10.1364/oe.432412

Cited by 3 publications

(4 citation statements)

References 49 publications

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“…The intensity distribution of a PSF at certain field position with certain misalignment parameters can be expressed according to Fourier optics and nodal aberration theory, which can be expressed as [ 15 ]

where

is an imaginary unit,

is the inverse Fourier transform, and

is a two-dimensional matrix representing the intensity distribution of the exit pupil surface (the element value of the matrix is 1 in the normalized aperture, and the rest are 0).

represents the wavefront phase at field

with system misalignment parameters

.…”

Section: Ellipticitymentioning

confidence: 99%

“…Importantly, based on the framework of nodal aberration theory,

can be expressed as the sum of two parts,

where

represents the aberration field in the original state which is determined by the optical design and mirror figures (unaffected by misalignments), and

represents the net aberration field induced by misalignments, which can be expressed as a linear function of

and

. The specific expression of

can be referred to [ 15 ].…”

Section: Ellipticitymentioning

confidence: 99%

“…where i is an imaginary unit, FT −1 is the inverse Fourier transform, and P is a twodimensional matrix representing the intensity distribution of the exit pupil surface (the element value of the matrix is 1 in the normalized aperture, and the rest are 0). W H, v can be referred to [15].…”

Section: Ellipticitymentioning

confidence: 99%

“…At present, active alignment methods are mainly divided into two classes: numerical method and analytic method. On the numerical computing side, sensitive table method (STM) [ 7 ], artificial neural networks method (ANN) [ 8 ], merit function (MF) regression method [ 9 , 10 , 11 ], differential wavefront sampling (DWS) [ 12 , 13 , 14 ] and image features [ 15 , 16 , 17 ] are widely used in ground alignment. The analytical method is mainly nodal aberration theory (NAT) [ 18 , 19 , 20 , 21 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

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Active Alignment of Large-Aperture Space Telescopes for Optimal Ellipticity Performance

Bai

et al. 2023

Sensors

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Ellipticity performance of space telescopes is important for exploration of dark matter. However, traditional on-orbit active optical alignment of space telescopes often takes “minimum wavefront error across the field of view” as the correction goal, and the ellipticity performance after correcting the wave aberration is not optimal. This paper proposes an active optical alignment strategy to achieve optimal ellipticity performance. Based on the framework of nodal aberration theory (NAT), the aberration field distribution corresponding to the optimal full field-of-view ellipticity is determined using global optimization. The degrees of freedom (DOFs) of the secondary mirror and the folded flat mirror are taken as the compensation DOFs to achieve the optimal ellipticity performance. Some valuable insights into aberration field characteristics corresponding to optimal ellipticity performance are presented. This work lays a basis for the correction of ellipticity for complicated optical systems.

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where

is an imaginary unit,

is the inverse Fourier transform, and

is a two-dimensional matrix representing the intensity distribution of the exit pupil surface (the element value of the matrix is 1 in the normalized aperture, and the rest are 0).

represents the wavefront phase at field

with system misalignment parameters

.…”

Section: Ellipticitymentioning

confidence: 99%

“…Importantly, based on the framework of nodal aberration theory,

can be expressed as the sum of two parts,

where

represents the aberration field in the original state which is determined by the optical design and mirror figures (unaffected by misalignments), and

represents the net aberration field induced by misalignments, which can be expressed as a linear function of

and

. The specific expression of

can be referred to [ 15 ].…”

Section: Ellipticitymentioning

confidence: 99%

Section: Ellipticitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Active Alignment of Large-Aperture Space Telescopes for Optimal Ellipticity Performance

Bai

et al. 2023

Sensors

Self Cite

View full text Add to dashboard Cite

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Perception of misalignment states for sky survey telescopes with the digital twin and the deep neural networks

Zhang,

Jia,

et al. 2023

Opt. Express

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Sky survey telescopes play a critical role in modern astronomy, but misalignment of their optical elements can introduce significant variations in point spread functions, leading to reduced data quality. To address this, we need a method to obtain misalignment states, aiding in the reconstruction of accurate point spread functions for data processing methods or facilitating adjustments of optical components for improved image quality. Since sky survey telescopes consist of many optical elements, they result in a vast array of potential misalignment states, some of which are intricately coupled, posing detection challenges. However, by continuously adjusting the misalignment states of optical elements, we can disentangle coupled states. Based on this principle, we propose a deep neural network to extract misalignment states from continuously varying point spread functions in different field of views. To ensure sufficient and diverse training data, we recommend employing a digital twin to obtain data for neural network training. Additionally, we introduce the state graph to store misalignment data and explore complex relationships between misalignment states and corresponding point spread functions, guiding the generation of training data from experiments. Once trained, the neural network estimates misalignment states from observation data, regardless of the impacts caused by atmospheric turbulence, noise, and limited spatial sampling rates in the detector. The method proposed in this paper could be used to provide prior information for the active optic system and the optical system alignment.

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Optical degradation correction of manufacturing-perturbed glass-plastic hybrid lens systems via a joint hardware-software optimization framework

Zhou,

Chen,

Yan

et al. 2024

Opt. Express

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Glass-plastic hybrid lens systems are increasingly critical in various optical applications due to their unique advantages and growing demands. Due to limitations in manufacturing processes and costs, the yield rate of glass-plastic hybrid lens systems in mass production struggles to match that of mature all-plastic ones. In this work, we propose a pioneering joint hardware-software optimization framework designed for correcting optical degradation in manufacturing-perturbed glass-plastic hybrid lens systems. Our framework begins with the establishment of a differentiable imaging simulation system that is capable of simulating various manufacturing errors. This system facilitates the preliminary estimation of manufacturing deviations across individual lenses without precise measurements. Subsequently, from the perspective of the hardware assembly process, we integrate active alignment of the glass aspherical lens to mitigate degradation caused by these deviations. Moreover, we introduce a novel and lightweight degradation correction network as post-processing software to address residual optical degradation without fine-tuning for each manufacturing-perturbed lens system, significantly reducing deployment costs for mobile devices. Extensive experiments validate the efficacy of our joint hardware-software optimization framework, showing substantial improvements in imaging quality and enhanced yield rates in mass production. Overall, our framework establishes a new paradigm for optical degradation correction in glass-plastic hybrid lens systems by synergizing the front-end lens assembly process with the back-end degradation correction method. This new paradigm represents an inaugural effort within the optical engineering domain.

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Active alignment of space astronomical telescopes by matching arbitrary multi-field stellar image features

Cited by 3 publications

References 49 publications

Active Alignment of Large-Aperture Space Telescopes for Optimal Ellipticity Performance

Active Alignment of Large-Aperture Space Telescopes for Optimal Ellipticity Performance

Perception of misalignment states for sky survey telescopes with the digital twin and the deep neural networks

Optical degradation correction of manufacturing-perturbed glass-plastic hybrid lens systems via a joint hardware-software optimization framework

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