Drift Performance and Chromatic Thermal Response of a Temperature Stabilized Solid-etalon Calibrator

Abstract

Etalon-based calibrators have rapidly gained popularity over the past decade in the field of high-precision radial velocity and high-resolution spectroscopy studies. Solid etalons are compact, pressure insensitive, commercially available alternatives to customized air spaced Fabry–Perot etalons. For tight-budget projects and weight-constricted missions, calibration system built from solid etalon is an interesting option to explore. For those, achievable spectral stability becomes the biggest question due to increased thermal sensitivity of the cavity material. Here, the design and performance of a low-cost solid-etalon calibrator is presented. A dual-loop temperature control system keeps the temperature fluctuations to within 1 mK rms when fully stabilized. Drift performance was tracked simultaneously with a laser frequency comb and the chromatic thermal response is measured through temperature tuning. The results indicate that a thermally controlled solid-etalon system can demonstrate sufficient short-term stability (<1 m s−1) for precise wavelength calibration in combination with a hollow-cathode lamp, and the measured drift and chromatic thermal response agree with theoretical predictions. Such systems are plausible candidates for cost-effective calibration of m s−1 level precision radial velocity instruments with improvement in thermal isolation, optimization in data processing, and long-term testing in the foreseeable future.