Spun highly-birefringent fiber for current sensing with inherent insensitivity to temperature
US-2017315158-A1 · Nov 2, 2017 · US
Fiber-optic current sensor with spun fiber and temperature compensation
US10345345B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-10345345-B2 |
| Application number | US-201514864422-A |
| Country | US |
| Kind code | B2 |
| Filing date | Sep 24, 2015 |
| Priority date | Mar 28, 2013 |
| Publication date | Jul 9, 2019 |
| Grant date | Jul 9, 2019 |
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Abstract
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A fiber-optic current sensor uses a highly-birefringent spun fiber as sensing fiber. The light is fed through a retarder, which is a detuned quarter-wave or half-wave retarder. It is shown that such detuning can be used to compensate for temperature dependencies of the sensing head.
First claim
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The invention claimed is: 1. A fiber-optic current sensor comprising a light source generating light in a wavelength range, a first linear polarizer receiving light from the light source and generating polarized light, a retarder receiving light from the first linear polarizer and having a retardation ρ=n·90°+ε, with n being an integer number and ε being a deviation from a retardation, a spun sensing fiber being wound N times into a loop to be placed around a current conductor carrying a current I, having a Verdet-constant V, a spin pitch ρ≤100 mm, and, in said wavelength range, an average linear beat length L LB ≤200 mm, wherein the average linear beat length is a linear beat length of a corresponding unspun fiber, wherein an input end of the spun sensing fiber receives light from the retarder, wherein a slow axis of the retarder is under an angle θ to a slow axis of the input end, a detector assembly adapted to determine a phase shift Δϕ between two polarization modes of light returning from said sensing fiber and to generate a signal indicative of said current, wherein the retarder is dimensioned such that it introduces a temperature dependence that counteracts the combined contributions to the scale factor temperature dependence of the Verdet constant V, the linear beat length L LB , the spin pitch p, and the bend-induced birefringence δ b . 2. The current sensor of claim 1 , wherein the retardation ρ is such that, for a given nominal magneto-optical phase shift 4NVI, temperature changes of the retarder yield variations of a temperature-smoothed normalized sensor scale factor SF′(ρ, L LB , p, θ, NVI, δ b ) that balance scale factor variations due to temperature changes of the spun sensing fiber in the sense that 1 SF ′ dSF ′ dT < 1 V dV dT 1 SF ′ dSF ′ dT < 1 V dV dT with dSF ′ dT = d ρ dT dSF ′ d ρ + d L LB _ dT dSF ′ d L LB _ + dp dT dSF ′ dp + dV dT dSF ′ dV + d δ b dT dSF ′
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- G01R15/246Primary
based on the Faraday, i.e. linear magneto-optic, effect · CPC title
using the Faraday or Voigt effect · CPC title
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- What does patent US10345345B2 cover?
- A fiber-optic current sensor uses a highly-birefringent spun fiber as sensing fiber. The light is fed through a retarder, which is a detuned quarter-wave or half-wave retarder. It is shown that such detuning can be used to compensate for temperature dependencies of the sensing head.
- Who is the assignee on this patent?
- Abb Research Ltd
- What technology area does this patent fall under?
- Primary CPC classification G01R15/246. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Jul 09 2019 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 8 related publications on this page (citations in our corpus or others sharing the same primary CPC).