A report discusses a computational- simulation study of phase- front propagation in the Laser Interferometer Space Antenna (LISA), in which space telescopes would transmit and receive metrological laser beams along 5-Gm interferometer arms. The main objective of the study was to determine the sensitivity of the average phase of a beam with respect to fluctuations in pointing of the beam. The simulations account for the effects of obscurations by a secondary mirror and its supporting struts in a telescope, and for the effects of optical imperfections (especially tilt) of a telescope. A significant innovation introduced in this study is a methodology, applicable to space telescopes in general, for predicting the effects of optical imperfections. This methodology involves a Monte Carlo simulation in which one generates many random wavefront distortions and studies their effects through computational simulations of propagation. Then one performs a statistical analysis of the results of the simulations and computes the functional relations among such important design parameters as the sizes of distortions and the mean value and the variance of the loss of performance. These functional relations provide information regarding position and orientation tolerances relevant to design and operation.
This work was done by Miltiadis Papalexandris of Caltech and Eugene Waluschka of Goddard Space Flight Center for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Physical Sciences category. NPO-30709.
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Tilt-Sensitivity Analysis for Space Telescopes
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Overview
The document presents a technical report on "Tilt Sensitivity Analysis for Space Telescopes," prepared by NASA’s Jet Propulsion Laboratory (JPL) and authored by Miltiadis Papalexandris and Eugene Waluschka. The primary focus of the study is the Laser Interferometer Space Antenna (LISA), which involves the transmission and reception of metrological laser beams along 5-Gm interferometer arms. The report addresses the critical need to assess how fluctuations in the pointing of these beams affect their average phase, particularly in the context of space telescopes.
A significant innovation introduced in this study is a new methodology for predicting the effects of optical imperfections, especially tilt, on telescope performance. This methodology employs Monte Carlo simulations to generate numerous random wavefront distortions, allowing researchers to analyze their impact on optical performance through computational simulations of beam propagation. The results of these simulations are subjected to statistical analysis, leading to the computation of functional relationships among key design parameters, such as the sizes of distortions and the mean value and variance of performance loss.
The findings provide essential insights into the tolerances required for the position and orientation of space telescopes, which are crucial for their design and operational effectiveness. By quantifying the effects of optical imperfections, the study aids in determining acceptable limits for motions like tilt and decenter, which are vital for maintaining the accuracy and reliability of space-based instruments.
The report emphasizes the importance of these analyses in the context of LISA's mission, which aims to detect gravitational waves and advance our understanding of the universe. The work is positioned as a significant contribution to the field of optical engineering and space science, offering a robust framework for future studies and applications in space telescope design.
Overall, this document encapsulates a comprehensive approach to addressing the challenges posed by optical imperfections in space telescopes, leveraging advanced simulation techniques to enhance the performance and reliability of these critical instruments. The research underscores the ongoing efforts by NASA and its partners to push the boundaries of space exploration and technology.
