Abstract:
A birefringent bias is provided to an optical sensor by the addition of one or more single birefringent elements where the total birefringence-length product remains within the accepted tolerances of current devices. The bias provided by two or more elements is such that where each element has a birefringence, a dB/dT and a coefficient of thermal expansion term, the elements are arranged in tamdem so that the combined birefringence terms equal the required birefringence bias and the dB/dT and coefficient of thermal expansion terms effectively cancel.
Abstract:
An optical temperature sensor for use in a temperature detector system having at least two birefringent crystal elements arranged in tandem. A collimated broad band light source is transmitted via a fiber optic cable, a polarizer to a first birefringent crystal element. The first crystal element decomposes the light wave into first and second orthogonally polarized waves and transmits the wave components to a second birefringent crystal element. The linearly polarized waves propagate through the birefringent crystals, and the environmental temperature introduces a temperature dependent phase shift between the two polarized waves. The light waves exit the second crystal to a second polarizer producing a modulated light spectrum. A focusing element collects the light and transmits it down another fiber optic cable. The cable transmits the light to an opto-electronic interface where the fringe pattern is extracted and a computer compatible signal is generated for a CPU. The CPU performs a Fourier transform on the fringe pattern, where the phase term for a selected frequency is the measure of the environmental temperature experienced by the birefringent crystals.
Abstract:
Guides d'ondes optiques utilisables dans des environnements à haute température, formés d'un corps guide d'ondes composé d'un premier grenat d'aluminium cristallin, qui est recouvert d'une couche épitaxiale d'un second grenat d'aluminium cristallin, lequel a un indice de réfraction plus bas que le premier grenat d'aluminium cristallin. Lorsque le manque de correspondance de réseaux cristallins entre le grenat servant de substrat et la couche de revêtement est suffisamment important, un effort est induit qui cause une compression résultant en une biréfringence dans la couche guide d'ondes. De tels guides d'ondes biréfringents maintiennent la polarisation de la lumière qui se propage à travers eux.
Abstract:
Détecteur s'utilisant dans un système de détection optique de température possédant un élément biréfringent constitué par une plaque d'oxyde métallique monocristal. Un spectre lumineux à bande large est transmis à travers un premier élément de polarisation linéaire, de façon à créer une onde à polarisation linéaire. Ladite onde, lorsqu'elle traverse la plaque d'oxyde métallique monocristal, se décompose entre une première et une deuxième onde à polarisation orthogonale. La propagation de l'onde à polarisation linéaire à travers la plaque d'oxyde métallique monocristal biréfringente introduit un décalage de phase dépendant de la température entre les deux ondes. Ensuite, un deuxième polarisateur linéaire combine la première et la deuxième onde à polarisation orthogonale, de façon à créer un spectre lumineux modulé possédant une configuration limite représentant une fonction de la température du courant s'exerçant sur ledit élément biréfringent. Un câble de fibre optique relié au deuxième élément de polarisation linéaire transporte le spectre lumineux modulé vers une interface opto-électronique où s'effectue l'extraction de la configuration limite, ainsi que la création d'un signal compatible avec un ordinateur, ce qui permet à un ordinateur central d'indiquer avec précision les conditions de température de courant environnantes atteignant 1000 °C, auxquelles est soumise la plaque monocristal de l'élément biréfringent.
Abstract:
An optical temperature sensor for use in a temperature detector system having at least two birefringent crystal elements arranged in tandem. A collimated broad band light source is transmitted via a fiber optic cable, a polarizer to a first birefringent crystal element. The first crystal element decomposes the light wave into first and second orthogonally polarized waves and transmits the wave components to a second birefringent crystal element. The linearly polarized waves propagate through the birefringent crystals, and the environmental temperature introduces a temperature dependent phase shift between the two polarized waves. The light waves exit the second crystal to a second polarizer producing a modulated light spectrum. A focusing element collects the light and transmits it down another fiber optic cable. The cable transmits the light to an opto-electronic interface where the fringe pattern is extracted and a computer compatible signal is generated for a CPU. The CPU performs a Fourier transform on the fringe pattern, where the phase term for a selected frequency is the measure of the environmental temperature experienced by the birefringent crystals.
Abstract:
A sensor for use in an optical temperature detector system having a birefringent element made of a single crystal metal oxide plate. A broad band light spectrum is transmitted through a first linear polarizing element to create a linearly polarized wave. The linearly polarized wave on passing through the single crystal metal oxide plate decomposes into first and second orthogonally polarized waves. Propagation of the linearly polarized wave through the birefringent single crystal metal oxide plate introduces a temprature dependent phase shift between the two waves. Thereafter, a second linear polarizer combines the first and second orthogonally polarized waves to create a modulated light spectrum having a fringe pattern, the fringe pattern being a function of the current temperature experienced by said birefringent element. A fiber optic cable connected to the second linear polarizing element carries the modulated light spectrum to an opto-electronic interface where the fringe pattern is extracted and a computer compatible signal is generated for a CPU to accurately indicate current environmental temperature conditions up to 1000 °C experienced by the single crystal plate crystal in the birefringent element.