Scaling Analyses for Large-Scale Space-Based Membrane Optics

Shepherd, Michael J.; Cobb, Richard; Palazotto, Anthony N.; Baker, William P.

doi:10.2514/1.45770

Cited by 3 publications

(1 citation statement)

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“…Similarly, in astronomical fields, a space-borne mirror with a large aperture must get rid of atmospheric turbulence to improve the space telescope's performance. Referring to the size of the James Webb Space Telescope, the future requirement for the diameter of primary mirrors is no less than 10 m [5]. The traditional optical reflector cannot meet this new requirement due to the fact that the solid monolithic lens is too large and heavy for the launch mass and storage size of current launch vehicles.…”

Section: Introductionmentioning

confidence: 99%

An inline surface measurement method for membrane mirror fabrication using two-stage trained Zernike polynomials and elitist teaching–learning-based optimization

Liu

Chen

Yang

et al. 2016

Meas. Sci. Technol.

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The accuracy of surface measurement determines the manufacturing quality of membrane mirrors. Thus, an efficient and accurate measuring method is critical in membrane mirror fabrication. This paper formulates this measurement issue as a surface reconstruction problem and employs two-stage trained Zernike polynomials as an inline measuring tool to solve the optical surface measurement problem in the membrane mirror manufacturing process. First, all terms of the Zernike polynomial are generated and projected to a non-circular region as the candidate model pool. The training data are calculated according to the measured values of distance sensors and the geometrical relationship between the ideal surface and the installed sensors. Then the terms are selected by minimizing the cost function each time successively. To avoid the problem of ill-conditioned matrix inversion by the least squares method, the coefficient of each model term is achieved by modified elitist teaching–learning-based optimization. Subsequently, the measurement precision is further improved by a second stage of model refinement. Finally, every point on the membrane surface can be measured according to this model, providing more the subtle feedback information needed for the precise control of membrane mirror fabrication. Experimental results confirm that the proposed method is effective in a membrane mirror manufacturing system driven by negative pressure, and the measurement accuracy can achieve 15 µm.

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Section: Introductionmentioning

confidence: 99%