Fiber-optic luminescence sensor utilizing interference in a thin layer structure
First Claim
1. A fiber-optic sensor for detecting a change in a physical quantity which comprisestwo substantially plane parallel interfaces spaced apart by a small enough distance to ensure that multiple reflections of optical energy at a given wavelength between said interfaces will give rise to constructive and destructive interference,a body of solid material attached to one of said interfaces capable of emitting photoluminescent optical energy when excited with incident optical energy, one of said photoluminescent and incident optical energies having a wavelength corresponding to said given wavelength,optical fiber means, for conveying incident optical energy to said interfaces and said body of solid material and conveying interference-affected incident and photoluminescent optical energies away from said interface, andmeans to allow the change in the physical quantity to affect the optical path length of optical energy in the separation between said parallel interfaces.
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Accused Products
Abstract
A fiber-optic sensor for measuring a physical quantity or sensing changes therein, consists of a transmitter and receiver unit respectively arranged to transmit and receive optical energy and an optical fiber for transmission of said optical energy to and from a sensor located at the measurement point. The sensor has at least one solid body, which is arranged to emit photoluminescent optical energy in at least one wavelength range, and a volume limited by at least two substantially plane-parallel surfaces, the separation of which is smaller than half the coherence length for either the transmitted or luminescent optical energy, whereby an interference pattern will differently affect the transmission of optical energy to the receiver unit as the optical length between said parallel surfaces changes with changes in the physical quantity being sensed.
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Citations
20 Claims
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1. A fiber-optic sensor for detecting a change in a physical quantity which comprises
two substantially plane parallel interfaces spaced apart by a small enough distance to ensure that multiple reflections of optical energy at a given wavelength between said interfaces will give rise to constructive and destructive interference, a body of solid material attached to one of said interfaces capable of emitting photoluminescent optical energy when excited with incident optical energy, one of said photoluminescent and incident optical energies having a wavelength corresponding to said given wavelength, optical fiber means, for conveying incident optical energy to said interfaces and said body of solid material and conveying interference-affected incident and photoluminescent optical energies away from said interface, and means to allow the change in the physical quantity to affect the optical path length of optical energy in the separation between said parallel interfaces.
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19. A fiber-optic measuring system for detecting a change in a physical quantity comprising a sensor, a transmitter and receiver unit, arranged to transmit and receive optical energy, and at least one optical fiber means for the transmission of optical energy to and from the sensor located at the point of measurement, characterized in that the sensor comprises at least one solid body, which is arranged to emit photoluminescent optical energy in at least one wavelength range, as well as a volume which is limited by at least two substantially plane-parallel interfaces the mutual separation of which is smaller than half the wavelength for the optical energy emitted from the transmitter unit or the photoluminescent optical energy emitted from the sensor.
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20. A method of detecting a change in the optical length between two substantially parallel surfaces generating optical interference patterns due to multiple reflections of optical energy in the gap between said two surfaces, which method comprises supplying incident optical energy and photoluminescent optical energy excited by said incident energy to said gap in such a manner that one of said optical energy supplies is more significantly affected by changes in the interference pattern than the other, and monitoring changes in intensity of at least one of said optical energy supplies to provide a measure of the change in the optical length.
Specification