Theoretical and experimental study on the testing accuracy of the image stabilization system of a space astronomical telescope

Li, Chenghao; He, Xiaoliang; Qi, Ji; Zhang, Xiaohui; Fan, Kuo-Chin

doi:10.1364/ao.388891

Cited by 6 publications

(6 citation statements)

References 25 publications

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“…By propagating (11) one time step, and by substituting ( 5), (6), and (10) in the resulting equation, we obtain…”

Section: Methods For Estimating the Covariance Matrices Of The Kalman...mentioning

confidence: 99%

“…Step 1: Design the suboptimal observer gain L. Use the pole placement method to compute the suboptimal observer gain L of the observer (10). This step can be performed in MATLAB by using the function place().…”

Section: Summary Of the Procedures For Estimating The Covariance Matr...mentioning

confidence: 99%

“…Once the data-driven Kalman filter gain is computed, we can substitute L K instead of the suboptimal gain L in the observer equation (10), to obtain an approximate Kalman filter. Here, it is important to emphasize that it is a good practice to iteratively perform steps 2 and 3 of the above-presented procedure.…”

Section: Summary Of the Procedures For Estimating The Covariance Matr...mentioning

confidence: 99%

“…Stabilization, disturbance rejection, and precise control of optical beams and optical spots are fundamental and ubiquitous problems that appear in a number of applications and optical systems. For example, these problems are crucial for the development of sensing and control systems for space and ground optical telescopes, [1][2][3][4][5][6][7][8][9][10][11][12] freespace optical communication terminals, 13,14 turbulence compensation systems, 13 precise laser beam steering and jitter compensation systems, 15,16,[16][17][18][19][20][21] and for other optical instruments and devices. [22][23][24][25][26][27] Optical spot and wave-front disturbances can originate from various sources and phenomena.…”

Section: Introductionmentioning

confidence: 99%

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Data-driven Estimation, Tracking, and System Identification of Deterministic and Stochastic Optical Spot Dynamics

Haber¹,

Krainak²

2023

Preprint

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Stabilization, disturbance rejection, and control of optical beams and optical spots are ubiquitous problems that are crucial for the development of optical systems for ground and space telescopes, free-space optical communication terminals, precise beam steering systems, and other types of optical systems. High-performance disturbance rejection and control of optical spots require the development of disturbance estimation and datadriven Kalman filter methods. Motivated by this, we propose a unified and experimentally verified data-driven framework for optical-spot disturbance modeling and tuning of covariance matrices of Kalman filters. Our approach is based on covariance estimation, nonlinear optimization, and subspace identification methods. Also, we use spectral factorization methods to emulate optical-spot disturbances with a desired power spectral density in an optical laboratory environment. We test the effectiveness of the proposed approaches on an experimental setup consisting of a piezo tip-tilt mirror, piezo linear actuator, and a CMOS camera.

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“…By propagating (11) one time step, and by substituting ( 5), (6), and (10) in the resulting equation, we obtain…”

Section: Methods For Estimating the Covariance Matrices Of The Kalman...mentioning

confidence: 99%

Section: Summary Of the Procedures For Estimating The Covariance Matr...mentioning

confidence: 99%

Section: Summary Of the Procedures For Estimating The Covariance Matr...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Data-driven Estimation, Tracking, and System Identification of Deterministic and Stochastic Optical Spot Dynamics

Haber¹,

Krainak²

2023

Preprint

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“…angles of the optical platform should be controlled to be not greater than 0.05" for our system. At present, it has been tested 48 to be less than 0.02" [44] in our lab, which can meet the 49 requirement of PSF ellipticity measurements.…”

mentioning

confidence: 99%

The Measurement of PSF Ellipticity of an Unobstructed Off-Axis Space Telescope: Error Analysis

Fan

Luo

et al. 2021

IEEE Access

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It is an effective method to detect weak gravitational lensing (WL) in the universe by measuring ellipticities of galaxies via astronomical telescopes. Optical properties of telescopes are critical to WL detections. To ensure the used telescopes to be competent, it is necessary to measure point spread function (PSF) ellipticity of telescopes in labs. In this paper, a way based on simulated star target imaging is proposed to measure PSF ellipticity of an unobstructed off-axis space telescope. Related errors are identified and modeled carefully for the first time. Effects of detector noises, micro-vibration of optical platforms, defocusing of simulated star target, wavefront error (WFE) and central obstruction of collimators on PSF ellipticity measurements of the telescope are analyzed. Results show that the measurement error of PSF ellipticity decreases from 0.0105 to 0.0043 by adopting 10 iterations of the iterative weighted centroiding algorithm when the SNR is under 24dB. To ensure PSF ellipticity measurement error is not larger than 0.01, the micro-vibration angle of the optical platform should be less than 0.05". When focal length of the collimator is twice that of the telescope, the measurement error of PSF ellipticity is under 0.01 if the defocusing of simulated star target is controlled to be not larger than 0.1 mm. In addition, WFE and central obstruction of collimators change PSF ellipticity measurement errors to different degrees at different fields of view (FOVs). Due to 20nm RMS WFE of the collimator, the maximum value of PSF ellipticity measurement errors over full FOVs is 0.1 and the average value is 0.0269. If the radius of central obscuration of the collimator is 150 mm, the maximum measurement error of PSF ellipticity over full FOVs is 0.0091.According to the results shown in this paper, significant reference for high accuracy measurements of PSF ellipticity of telescopes can be provided. INDEX TERMSWeak gravitational lensing, unobstructed off-axis space telescope, PSF ellipticity measurements, error analysis. I. INTRODUCTION33 Weak gravitational lensing (WL) is a slight deflection of the 34 light from background galaxies through a gravitational field 35 formed by dark matter and ordinary matter [1]. WL is a good 36 probe to study dark matter and dark energy in the universe so 37 that it becomes one of the most powerful tools for 38 cosmologists. WL enables to map dark matter and detect dark 39 energy by statistically quantifying the shear distortions 40 encoded in the observed shapes of background galaxies, 41 namely, galaxy ellipticities [2]-[4]. Thus, precisely obtaining 42 ellipticities of galaxies via astronomical telescopes is critical 43 to WL detections [5]. 44 However, ellipticities of galaxies are typically distorted 45 only approximately 1% in size by WL [6], [7]. It is a big 46 challenge to measure such tiny WL signals. Currently, the 47 distortions and unbiased estimates of galaxy shapes are 48 accessed by statistically averaging a very large number of 49 samples [8], [9]. Several la...

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Self-adaptive fusion method for scientific CMOS image sensors with variable gain ratios and background values

Zhou

Yang

et al. 2023

Review of Scientific Instruments

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Image diagnosis is an important technique in transient process research of high-energy physics. High dynamic range scenes require high linear dynamic range imaging systems. Scientific CMOS (sCMOS) image sensors have widely been used in high-energy physics, nuclear medical imaging, and astronomical observation because of their advantages in the high linear dynamic range. In this paper, we study the gain ratio variation and background value variation of commercial sCMOS image sensors. A self-adaptive fusion method is proposed to realize the fusion of high linear dynamic range images. The proposed method only uses the high gain image and the low gain image of the sCMOS image sensor to evaluate the gain ratio and the background compensation. The measured results show that the error rates of the evaluated gain ratio and background compensation are less than 2% and 6%. Test results show that the self-adaptive fusion method realizes well the fusion effects, which efficiently avoids the influence of gain ratio variation and background value variation.

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Theoretical and experimental study on the testing accuracy of the image stabilization system of a space astronomical telescope

Cited by 6 publications

References 25 publications

Data-driven Estimation, Tracking, and System Identification of Deterministic and Stochastic Optical Spot Dynamics

Data-driven Estimation, Tracking, and System Identification of Deterministic and Stochastic Optical Spot Dynamics

The Measurement of PSF Ellipticity of an Unobstructed Off-Axis Space Telescope: Error Analysis

Self-adaptive fusion method for scientific CMOS image sensors with variable gain ratios and background values

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