13 October 1986 A Tunable, Solid, Fabry-Perot Etalon For Solar Seismology
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Abstract
We have designed and fabricated a solid etalon from a 50-mm diameter wafer of optical-quality lithium niobate. The finished etalon has a free spectral range of 0.325 nm at 588 nm. The parallel faces are coated with silver, and the central 15-mm aperture of the etalon has a finesse of 18.6. The reflective faces double as electrodes, and application of voltage will shift the passband. This feature was used in a servo circuit to stabilize the passband' againsttemperature and tilt-induced drifts to better than three parts in 10. The etalon will be incorporated into a servo-controlled, tunable filter at the APL Solar Observatory. Because of its large aperture and high acceptance angle, it does not require that the host telescope or the filter be scanned mechanically in the course of normal solar measurements. Operated in the stabilized mode for day-long sessions, this filter alternately samples the wings of a narrow atomic absorption line in the solar spectrum and produces a signal proportional to velocity on the solar disk. The Fourier transform of this signal yields information on acoustic waves in the solar interior.
© (1986) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David M. Rust, David M. Rust, Clive H. Burton, Clive H. Burton, Achim J. Leistner, Achim J. Leistner, } "A Tunable, Solid, Fabry-Perot Etalon For Solar Seismology", Proc. SPIE 0627, Instrumentation in Astronomy VI, (13 October 1986); doi: 10.1117/12.968071; https://doi.org/10.1117/12.968071
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