An Innovative Method for the Alignment of Astronomical Telescopes

Luna, Esther Martínez; Zazueta, Salvador; Gutiérrez, L.

doi:10.1086/319330

Cited by 3 publications

(1 citation statement)

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“…In the previous studies, there are many approaches to align telescopes [2]. All these methods can be divided into three categories and the most commonly used one is called the direct wavefront sensing (WFS) method [3]- [5], such as sensitive table method [6], merit function regression method [7], Shack-Hartmann wavefront sensing method [8], and computer-aided alignment (CAA) method [9]- [12], which needs to add additional optical components in the system to detect the wavefront errors, increasing the complexity of optical systems.…”

Section: Introductionmentioning

confidence: 99%

Telescopes Alignment Using the Sharpness Function Method Based on Undersampled Images

Liu

Zhang

et al. 2019

IEEE Photonics J.

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In astronomy, the images are sometimes undersampled. In the previous research works, image reconstructions have to be employed to recover the lost information from a set of undersampled images to achieve a high-resolution image using dithering or drizzle methods, which increase the complexity of alignment processes and make the real-time correction impossible. In this paper, the telescope is aligned by changing the positions of the secondary mirror using sharpness function method combined with the stochastic parallel gradient descent algorithm based on both well-sampled and undersampled images without image reconstructions. To improve the accuracy and robustness of the alignment, a new metric called relative root mean square error is proposed. Both numerical simulations and experiments are implemented, and the alignment precisions are measured by wavefront residual errors using Shack-Hartmann wavefront sensors. The results show that the correction processes can converge stably and quickly whether the images are well-sampled or undersampled. In experiments, the average wavefront error is 0.0595 λ for undersampled images and 0.0548 λ for well-sampled images after the telescope alignment, indicating that the misalignments are well compensated for both well-sampled and undersampled images.

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Section: Introductionmentioning

confidence: 99%

Telescopes Alignment Using the Sharpness Function Method Based on Undersampled Images

Liu

Zhang

et al. 2019

IEEE Photonics J.

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High precision automated alignment procedure for two-mirror telescopes

et al. 2019

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A significant challenge in the production of Earth observation satellites is the precise alignment of the telescope optical components. We have developed a strategy to perform automated alignment of two-mirror telescopes for use in a realistic factory-based setting. A Ritchey-Chrétien telescope was used as an example. The secondary mirror was mounted on a high precision hexapod and its misalignment inferred from the Zernike coefficients for tilt, defocus, and coma, as measured by a phase-shifting interferometer. The required corrections to the position of the secondary mirror were implemented using an integral controller and alignment was achieved within minutes, compared to within days when using a manual alignment process. The Zernike coefficient for each aberration was reduced to within one standard deviation of the fluctuations due to residual instability (48 nm).

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The Role of Amateur Observatories in Falak Education in Malaysia

2014

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An Innovative Method for the Alignment of Astronomical Telescopes

Cited by 3 publications

References 10 publications

Telescopes Alignment Using the Sharpness Function Method Based on Undersampled Images

Telescopes Alignment Using the Sharpness Function Method Based on Undersampled Images

High precision automated alignment procedure for two-mirror telescopes

The Role of Amateur Observatories in Falak Education in Malaysia

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