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

Fan, Kuo-Chin; Luo, Jianqiao; He, Xiaoliang; Li, Chenghao; Zhang, Xiaohui

doi:10.1109/access.2021.3108638

Cited by 3 publications

(2 citation statements)

References 46 publications

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“…Under the action of tension 𝑇 1 ′ , its deformation form is shown in Figure 3. The reduction of the wrap angle due to the existence of bending stiffness can be expressed as the formula (10).…”

Section: T T T T T T =−   =+  (8)mentioning

confidence: 99%

“…At present, domestic and foreign scholars have relatively little research on the cable traction system of unmanned cars under the non-electromagnetic remote control mode. The degree of expandability, modularity, and rapid installation is not high, so there is still some room for research [9][10] . Therefore, it is urgent to design a stable, strong security suitable for a variety of terrain control electro-optical unmanned system measurement and control devices.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Research on Dynamic Modeling Measurement and Control of Cable Traction Devices for Electro-Optical Unmanned Systems

Shen

Chen²,

Zhu³

et al. 2023

J. Phys.: Conf. Ser.

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In order to realize the high-precision variable direction cable control of the electro-optical unmanned system in non-electromagnetic remote control, a cable traction device measurement and control with characteristics of variable direction traction, rapid installation, and lightweight portability were proposed. Fan-shaped connect rod mechanism and U-shaped groove fixed pulley group were added to it, which can realize multi-direction traction without derailment on the basis of the cable limit and alleviate the cable fracture caused by mechanical wear. Introducing Euler transformation and analyzing the dynamics of the cable, the whole operation process, and the tension detection model was established. A Kalman Filter traction planning method was proposed to solve the problems of inertia delay and emergency stop of the unmanned vehicles after a sudden direction change. In order to verify the effectiveness, an experimental platform for the cable traction system of a 50kg wheeled and 150kg tracked unmanned system was built for simulation and experimental testing. The results show that the cable system has good dynamic variable traction, which can meet the multi-terrain control ability of an electro-optical unmanned system in a complex field environment.

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Section: T T T T T T =−   =+  (8)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Research on Dynamic Modeling Measurement and Control of Cable Traction Devices for Electro-Optical Unmanned Systems

Shen

Chen²,

Zhu³

et al. 2023

J. Phys.: Conf. Ser.

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Wave aberration corrections in PSF ellipticity measurements of astronomical telescopes using a multi-objective optimization

Xu,

Luo,

et al. 2024

Appl. Opt.

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The weak gravitational lensing (WGL) produces a shear effect on the observed galactic ellipticity that is much smaller than the endogenous ellipticity of the galaxy itself. Achieving such a high-level astronomical observation requires the superior performance of telescopes. To ensure the optical properties of telescopes to be competent in WGL detections, it is very necessary to measure point spread function (PSF) ellipticity of telescopes in labs. In this paper, a 2 m off-axis telescope that would be used to detect WGL in space is analyzed and studied. A collimator whose aperture is 2 m has been built to measure PSF ellipticity of the telescope. The wave aberrations of the collimator are roughly equal to those of the telescope, so they are important systematical errors and must be removed. However, it is difficult to precisely measure the wave aberrations of optical systems that have large apertures and long focal lengths. In addition, a 2 m flat mirror, which is indispensable to measure wave aberrations of optical systems, has significant surface errors. In this paper, a multi-objective optimization method is proposed to eliminate the effects of wave aberrations on PSF ellipticity measurements of the telescope. By constructing an equivalent model, the wave aberrations from collimators and flat mirrors can be corrected so that PSF ellipticity measurement error is reduced to within 0.01. Measurement accuracy of PSF ellipticity of the telescopes can be improved significantly.

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Multi-Source Data Fusion Method for the Truss Structure Stability Measurement of Space Telescope

Zhang

et al. 2022

Applied Sciences

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It is necessary for large aperture space telescopes to achieve high measurement accuracy for mechanical reference mounting surfaces, complex deformation conditions, and difficulty in describing spatial geometric properties. In this manuscript, we propose a measurement method for evaluating the deformation of the trusses structure by fusing multiple sources of data. The multi-source data are obtained from the theodolite, laser tracker, and photogrammetry systems. The datum alignment of the laser tracker and photogrammetry coordinate systems is achieved by establishing the transition coordinate system method of the datum platform, and the alignment accuracy (3σ) is about 8.8″, 5.1″ and 4.2″. Using the laser tracker to establish the relationship between the cubic mirror coordinate system and the geometric coordinate system of the mounting part, the fast and high-precision measurement of the mounting angle of the cubic prism is realized, and the measurement accuracy reaches 2″. The data from multiple sources are fused through datum transfer and alignment to establish a cosine matrix transfer chain between the mechanical characteristic coordinate system of each component and the transition coordinate system of the datum platform, and the Eulerian rotation angle is obtained to describe the angular relationship between the components after solving. Based on the Monte Carlo mathematical error modeling analysis, the datum transfer and alignment simulations were carried out, and related experiments were conducted. The experiments show that the transfer error (3σ) of the XYZ rotation angle is less than 20.6″ after the datum transfer, the maximum error is within 3″ compared to the simulation results, and the deviation of the comparison photographic measurement data is less than 7.6″. The datum transfer method combined with photogrammetry can describe the deformation trend of large-size trusses under different load conditions more objectively and reasonably.

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

Cited by 3 publications

References 46 publications

Research on Dynamic Modeling Measurement and Control of Cable Traction Devices for Electro-Optical Unmanned Systems

Research on Dynamic Modeling Measurement and Control of Cable Traction Devices for Electro-Optical Unmanned Systems

Wave aberration corrections in PSF ellipticity measurements of astronomical telescopes using a multi-objective optimization

Multi-Source Data Fusion Method for the Truss Structure Stability Measurement of Space Telescope

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