Frequency stability of the mode spectrum of broad bandwidth Fabry-Pérot interferometers

Jennings, Jeff; Terrien, Ryan C.; Fredrick, Connor; Grisham, M.; Notcutt, M.; Halverson, Samuel; Mahadevan, Suvrath; Diddams, Scott A.

doi:10.1364/osac.393551

Cited by 7 publications

(4 citation statements)

References 38 publications

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“…The HPF spectrographs and its corresponding Fabry-Pérot interferometer operates in the near infrared between 8200 Å and 12800 Å, roughly covering the z, y, and J bands, while Espresso is sensitive in the visible domain between 3800 Å and 7900 Å. More importantly, the HPF Fabry-Pérot etalon is designed with a high finesse of F ≈ 40 to achieve a small intrinsic linewidth (≈ 800 MHz or ≈ 0.85 km/s), substantially narrower than the instrumental resolution (Jennings et al 2020). The Espresso Fabry-Pérot etalon, however, has a lower finesse of F ≈ 12 and the Fabry-Pérot lines are clearly resolved and appear about 20 % wider than the intrinsic linewidth.…”

Section: Comparison With the Hpf Faby-pérotmentioning

confidence: 99%

Chromatic drift of the Espresso Fabry-Pérot etalon

Schmidt

Chazelas

Dumusque

et al. 2022

A&A

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In the last decade, white-light illuminated Fabry-Pérot interferometers have been established as a widely used, relatively simple, reliable, and cost-effective way to precisely calibrate high-resolution echelle spectrographs. However, a recent study reported a chromatic drift of the Fabry-Pérot interferometer installed at the Habitable-zone Planet Finder (HPF) spectrograph. In particular, they found that the variation of the etalon effective gap size is not achromatic, as has usually been assumed, but that, in fact, it depends on wavelength. Here, we present a similar study of the Espresso Fabry-Pérot interferometer. Using daily calibrations spanning a period of over 2.5 years, we also find clear evidence for a chromatic drift with an amplitude of a few cm/s per day with a characteristic, quasi-oscillatory dependence on wavelength. We conclude that this effect is probably caused by the aging of the dielectric mirror coatings and we expect that similar chromatic drifts might affect all Fabry-Pérot interferometers used for the calibration of astronomical spectrographs. However, we also demonstrate that the chromatic drift can be measured and, in principle, corrected using only standard calibrations based on hollow cathode lamp spectra.

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Section: Comparison With the Hpf Faby-pérotmentioning

confidence: 99%

Chromatic drift of the Espresso Fabry-Pérot etalon

Schmidt

Chazelas

Dumusque

et al. 2022

A&A

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show abstract

“…Alternatively a line spectrum may be generated using a laser comb (Phillips et al 2012;Wilken et al 2012;Metcalf et al 2019). Finally a reference spectrum may be generated using a Fabry-Pérot etalon (Wildi et al 2010;Reiners et al 2014;Bauer et al 2015;Schwab et al 2015;Jennings et al 2020). In the case of iodine cells and thorium-argon (ThAr) lamps, the wavelengths of the spectral lines are inherently stable.…”

Section: Introductionmentioning

confidence: 99%

Using birefringent elements and imaging Michelsons for calibration of high precision planet finding spectrographs

Schou

2022

Preprint

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Context. One of the main methods used for finding extrasolar planets is the radial velocity technique, in which the Doppler shift of a star due to an orbiting planet is measured. These measurements are typically performed using cross-dispersed echelle spectrographs. Unfortunately such spectrographs are large and expensive and their accurate calibration continues to be challenging. Aims. The aim is to develop a different way to provide a calibration signal. Methods. A commonly used way to introduce a calibration signal is to insert an iodine cell in the beam. Disadvantages of this include that the lines are narrow, do not cover the entire spectrum and that light is absorbed. Here I show that inserting a birefringent element or an imaging Michelson, combined with Wollaston prisms eliminates these three shortcomings, while maintaining most of the benefits of the iodine approach.Results. The proposed designs can be made very compact, thereby providing a convenient way of calibrating a spectrograph. Similar to the iodine cell approach, the calibration signal travels with the stellar signal, thereby reducing the sensitivity to spectrograph stability. The imposed signal covers the entire visible range and any temperature drifts will be consistent and describable by a single number. Based on experience with similar devices used, in a different configuration, by the Helioseismic and Magnetic Imager, it is shown that the calibration device can be made stable at the 0.1 m/s level, over a significant wavelength range, on short to medium time scales. Conclusions. While promising, many details still need to be worked out. In particular a number of laboratory measurements are required in order to finalize a design and estimate actual performance and it would be desirable to make a proof of concept.

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“…Alternatively, a line spectrum may be generated using a laser comb (Phillips et al 2012;Wilken et al 2012;Metcalf et al 2019). Finally, a reference spectrum may be generated using a Fabry-Pérot etalon (Wildi et al 2010;Reiners et al 2014;Bauer et al 2015;Schwab et al 2015;Jennings et al 2020). In the case of iodine cells and ThAr lamps, the wavelengths of the spectral lines are inherently stable.…”

Section: Introductionmentioning

confidence: 99%

Using birefringent elements and imaging Michelsons for the calibration of high-precision planet-finding spectrographs

Schou

2022

A&A

View full text Add to dashboard Cite

Context. One of the main methods used for finding extrasolar planets is the radial velocity technique, in which the Doppler shift of a star due to an orbiting planet is measured. These measurements are typically performed using cross-dispersed echelle spectrographs. Unfortunately, such spectrographs are large and expensive, and their accurate calibration continues to be challenging. Aims. The aim is to develop a different way to provide a calibration signal. Methods. A commonly used way to introduce a calibration signal is to insert an iodine cell in the beam. Disadvantages of this include that the lines are narrow, do not cover the entire spectrum, and light is absorbed. Here I show that inserting a birefringent element or an imaging Michelson, combined with Wollaston prisms, eliminates these three shortcomings while maintaining most of the benefits of the iodine approach. Results. The proposed designs can be made very compact, thereby providing a convenient way of calibrating a spectrograph. Similar to the iodine cell approach, the calibration signal travels with the stellar signal, thereby reducing the sensitivity to spectrograph stability. The imposed signal covers the entire visible range, and any temperature drifts will be consistent and describable by a single number. Based on experience with similar devices that were used in a different configuration by the Helioseismic and Magnetic Imager, it is shown that the calibration device can be made stable at the 0.1 m/s level over a significant wavelength range on short to medium timescales. Conclusions. While the design is promising, many details still need to be worked out. In particular, a number of laboratory measurements are required in order to finalize a design and estimate actual performance, and it would be desirable to make a proof of concept.

show abstract

Frequency stability of the mode spectrum of broad bandwidth Fabry-Pérot interferometers

Cited by 7 publications

References 38 publications

Chromatic drift of the Espresso Fabry-Pérot etalon

Chromatic drift of the Espresso Fabry-Pérot etalon

Using birefringent elements and imaging Michelsons for calibration of high precision planet finding spectrographs

Using birefringent elements and imaging Michelsons for the calibration of high-precision planet-finding spectrographs

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