Water-in-fuel sensor
First Claim
1. A water-in-fuel sensor comprising:
- a probe for immersing in liquid fuel, the probe comprising an uncoated polymer optical fibre (POF) for guiding optical radiation, the POF being made of water-permeable plastic material and having a grating section comprising a periodic refractive index modulation that exhibits a characteristic reflection or transmission profile;
a light source optically coupled to the probe to deliver optical radiation into the POF; and
a detector arranged to receive optical radiation reflected from or transmitted by the grating section and monitor the characteristic reflection or transmission profile of the grating section,wherein the POF permits water dissolved in the liquid fuel to diffuse into the POF at the grating section to cause a water-specific change to the characteristic reflection or transmission profile of the grating section.
1 Assignment
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Accused Products
Abstract
An uncoated polymer optical fiber (POF) that is sensitive to a chemical (e.g. water) and is used to generate a detectable change in its optical properties for the purpose of detecting that chemical when it is dissolved in liquid fuel. The presence of the chemical directly affects the optical properties of the optical fiber. The POF may be made of water-permeable plastic material and may have a grating section comprising a periodic refractive index modulation that exhibits a characteristic reflection or transmission profile to be monitored by a detector. The water-permeability of the constituent material of the POF permits diffusion of water into the fiber, thereby affecting its refractive index or geometry and hence altering the characteristic reflection or transmission profile of the grating section.
10 Citations
18 Claims
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1. A water-in-fuel sensor comprising:
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a probe for immersing in liquid fuel, the probe comprising an uncoated polymer optical fibre (POF) for guiding optical radiation, the POF being made of water-permeable plastic material and having a grating section comprising a periodic refractive index modulation that exhibits a characteristic reflection or transmission profile; a light source optically coupled to the probe to deliver optical radiation into the POF; and a detector arranged to receive optical radiation reflected from or transmitted by the grating section and monitor the characteristic reflection or transmission profile of the grating section, wherein the POF permits water dissolved in the liquid fuel to diffuse into the POF at the grating section to cause a water-specific change to the characteristic reflection or transmission profile of the grating section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of detecting water in fuel, the method comprising:
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immersing a probe in liquid fuel, the probe comprising a polymer optical fibre (POF) for guiding optical radiation, the POF being made of water-permeable plastic material and having a grating section comprising a periodic refractive index modulation that exhibits a characteristic reflection or transmission profile; delivering optical radiation to the probe from a light source optically coupled to the probe; receiving optical radiation reflected from or transmitted by the grating section at a detector; and monitoring the characteristic reflection or transmission profile of the grating section, wherein the POF is uncoated, whereby water dissolved in the liquid fuel diffuses into the POF at the grating section to cause a water-specific change to the characteristic reflection or transmission profile of the grating section.
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Specification