Determination of distortion corrections for a fixed length optical cavity pressure standard

Ricker, Jacob E.; Douglass, Kevin O.; Hendricks, Jay H.; White, Sarah V.; Syssoev, Sergei

doi:10.1016/j.measen.2021.100286

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…The relative cavity length fluctuations determine the fluctuations in frequency (∆𝑓) of the locked laser, ∆𝑓 𝑓 ⁄ ~∆𝐿 𝐿 𝑐 ⁄ [17,18], where ∆𝐿 is the length fluctuations due to temperature & pressure and Lc is the cavity length. A cavity length of Lc=150 mm is chosen for our design, for ease of measurement comparisons with other NMIs [19]. The free spectral range is, 𝐹𝑆𝑅 = 𝑐 2𝑛𝐿 𝑐 ⁄ = 1 𝐺𝐻𝑧 [Fig.…”

Section: Result: Design and Constructionmentioning

confidence: 99%

Laser based optical interferometer manometer design for primary pressure standard in India

Das¹,

Ghosh²,

Kumar³

et al. 2023

Preprint

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The SI unit of pressure, i.e. Pascal is realized with mechanical devices such as ultrasonic interferometer manometers and pressure balances for the pressure range 1 Pa to 100 kPa. Recently, optical interferometer manometers are being used to realize Pascal. Such a realization is mercury-free and environmentally friendly and does not depend on any mechanical motions as in piston gauges and is based on physical constants. It consists of an optical Fabry-Perot cavity as a refractometer and is based on the measurement of the resonant frequency of the cavity using lasers. In this paper, we report the theoretical calculations for such an optical cavity and discuss various parameters for the laser required for developing such a cavity-based refractometer system. We present the mechanical design for the dual cavity and the effect of pressure on the elastic deformation of such cavities using finite element analysis. We present an all-fiber optical set-up for the lasers, to be used for the next generation of primary pressure standards in the barometric region of pressure at CSIR-National physical laboratory, India.

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Section: Result: Design and Constructionmentioning

confidence: 99%

Laser based optical interferometer manometer design for primary pressure standard in India

Das¹,

Ghosh²,

Kumar³

et al. 2023

Preprint

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“…The spacer of the FP cavity is made of Zerodur ® class 0, chosen for its low coefficient of thermal expansion, given by the manufacturer to be 1.6 × 10 −8 K ⁄ . In addition, this material is selected for its high resistance to helium permeation, if this gas is to be used [11]. On this Zerodur ® block, two fused silica mirrors, coated with a dielectric layer resulting in a reflection coefficient of (99.97 ± 0.01) % at 532 nm, are optically bounded.…”

Section: Experimental Set-upmentioning

confidence: 99%

Status and performance of the LNE-Cnam Fabry-Perot refractometer

Rezki,

Silvestri,

Bentouati

et al. 2024

Proceedings of the 7th IMEKO TC16 Conference on Pressure and Vacuum Measurement

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We present the status of the single-cavity Fabry-Perot interferometer developed at the LNE-Cnam laboratory used for thermodynamic pressure measurements within the range of 100 Pa to 100 kPa. After characterizing the intrinsic parameters of the refractometer, this optical sensor is used to measure the refractivity of nitrogen. Then, using the Lorentz-Lorenz equation and knowing the refractive virial coefficients at 532 nm, it is possible to deduce its density. Measuring the temperature of the gas makes it possible to determine its pressure using an equation of state. Once the temperature and pressure stability of the gas inside the optical sensor have been achieved at sub-mK and mPa levels, respectively, the expanded uncertainty of the sensor is evaluated to be [(𝟓𝟎 𝐦𝐏𝐚) 𝟐 + (𝟐𝟐 × 𝟏𝟎 −𝟔 • 𝒑) 𝟐 ] 𝟏 𝟐 ⁄ .In order to further decrease this uncertainty, several approaches and solutions are given, leading to more accurate and reliable pressure measurements.The developed optical cavity operates as a high-resolution pressure sensor with an objective of complementing and eventually replacing conventional pressure standards, such as the force-balanced piston gauge and capacitance diaphragm gauge, that are based on the classical definition of pressure.I.

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“…The pressure distortion coefficient 𝑑 𝑚 can be determined by the so-called two-gas method [13]. It is to compare the pressure measurements at a same pressure usually generated by a piston gauge (PG), with two gases of very different and known refractive indices, respectively.…”

Section: B Pressure Distortion Coefficient 𝑑 𝑚mentioning

confidence: 99%

Working equation for a Fabry-Perot cavity based optical pressure standard

Yang,

Egan,

Rubin

2024

Proceedings of the 7th IMEKO TC16 Conference on Pressure and Vacuum Measurement

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From basics of Fabry-Perot (FP) resonator and roundtrip phase, a complete working equation for a FP cavity based optical pressure standard (OPS) is derived and presented which includes corrections of reflection phase-shift, diffraction and pressure-induced distortion. The correction from diffraction, i.e. Gouy phase, is negligible. To operate an OPS as a primary standard, two unknown parameters, i.e. mirror dispersion coefficient 𝝐 𝜶 and pressure distortion coefficient 𝒅 𝒎 , in the working equation should be determined independently. Methods to determine 𝝐 𝜶 and 𝒅 𝒎 are described and applied to an OPS developed at the National Institute of Metrology (NIM), China. Thermodynamic effect observed in the determination of 𝒅 𝒎 is also discussed.

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Determination of distortion corrections for a fixed length optical cavity pressure standard

Cited by 6 publications

References 5 publications

Laser based optical interferometer manometer design for primary pressure standard in India

Laser based optical interferometer manometer design for primary pressure standard in India

Status and performance of the LNE-Cnam Fabry-Perot refractometer

Working equation for a Fabry-Perot cavity based optical pressure standard

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