A tunable, solid, Fabry-Perot etalon for solar seismology.
Abstract
A solid etalon has been designed and fabricated 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 against temperature and tilt-induced drifts to better than three parts in one billion. 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.
- Publication:
-
Instrumentation in astronomy VI
- Pub Date:
- January 1986
- DOI:
- 10.1117/12.968071
- Bibcode:
- 1986SPIE..627...39R
- Keywords:
-
- Drift (Instrumentation);
- Etalons;
- Helioseismology;
- Solar Instruments;
- Fabrication;
- Solar Interior;
- Sound Waves;
- Stellar Interiors;
- Thermal Stability;
- Tunable Lasers;
- Instrumentation and Photography;
- Fabry-Perot Spectrometers