US 5,473,428 A · Interferometric temperature sensing system having a coupled laser diode wherein the magnitude is adjusted corresponding to a prior feed-back laser beam

Abstract

An interferometric temperature sensing system provides a simplified design for accurately processing an interference fringe pattern using self coupling effects of a laser detection element, where a laser diode and an optical detection element are combined in one package. Accordingly, the present invention is easily made and the measurement of temperatures within a wide range can be easily performed. The interferometric temperature sensing system contemplates an interferometric sensor having one or more reflecting surfaces and different optical paths corresponding to a temperature of a measured object or environment; a laser detection element for emitting a first laser beam in response to a predetermined modulated driving signal and adjusting the amount of the emitted first laser beam corresponding to a second laser beam, the laser detection element also detects the magnitude of an adjusted third laser beam to generate a sense signal that includes temperature information; an optical coupler for propagating the emitted first laser beam to a proximal end of the interferometric sensor, coupling the laser beams fed back through the proximal end of the interferometric sensor into the second laser beam, and then propagating the coupled beam to the laser detection element; a modulated signal generator for generating the modulated driving signal in response to a predetermined pilot signal; and a temperature processor for generating the pilot signal, and detecting a temperature change direction and a fringe number of the sense signal to calculate a temperature change.

Claims38

Dependent claims

An interferometric temperature sensing system having a coupled laser diode, said system comprising:

interferometric sensing means having at least a single reflector and providing different optical paths for laser beams corresponding to a temperature of a measured object or an environment, said interferometric sensing means for receiving a remainder portion of an emitted laser beam at a first end and feeding back a secondary reflected portion of said emitted laser beam after said remainder portion of said emitted laser beam is reflected by said single reflector positioned on a second end of said interferometric sensing means opposite said first end;
laser detection means for emitting said emitted laser beam in response to a predetermined modulated driving signal, and adjusting a magnitude of said emitted laser beam to correspond to a magnitude of a prior feed-back laser beam, said laser detection means generating a sense signal indicative of temperature information in dependence upon a degree of adjustment of the magnitude of said emitted laser beam;
optical coupling transmission means for transmitting said emitted laser beam to said first end of said interferometric sensing means, coupling said secondary reflected portion of said emitted laser beam with a primary reflected portion of said emitted laser beam into a combined laser beam, and then transmitting said combined laser beam to said laser detection means;
driving signal generation means for generating said predetermined modulated driving signal in response to a predetermined pilot signal;
and
temperature processing means for generating said predetermined pilot signal, and detecting temperature change direction and a fringe number indicated by said sense signal to calculate a temperature change value.

3 more elements

An interferometric temperature sensing system having a coupled laser diode, said system comprising:

optical transmission means having first and second ends, for reflecting on said second end a first laser beam propagated from said first end to produce a primary reflected laser beam, said optical transmission means coupling said primary reflected laser beam and a secondary reflected laser beam propagated to said second end into a coupled laser beam including an interference fringe pattern caused by a phase difference between said primary and secondary reflected laser beams, said coupled laser beam being transmitted to said first end of said optical transmission means;
interferometric sensing means for varying an optical path in response to an environmental temperature, said interferometric sensing means having a first end connected to said second end of said optical transmission means for feeding back said secondary reflected laser beam to said second end of said optical transmission means through said varying optical path;
laser detection means for emitting said first laser beam in response to a modulated driving signal, and adjusting a magnitude of said first laser beam in dependence upon a magnitude of a prior coupled beam transmitted to said first end of said optical transmission means, said laser detection means generating a sense signal indicative of temperature information in dependence upon a degree of adjustment of the magnitude of said first laser beam;
modulated signal generation means for generating said modulated driving signal in response to a predetermined pilot signal;
and
temperature processing means for generating said predetermined pilot signal, and for amplifying, filtering and processing said sense signal to convert said sense signal into an indicated temperature.

3 more elements

An interferometric temperature sensing system having a coupled laser diode, said system comprising:

optical coupling transmission means having first and second ends, for propagating a first laser beam from said first end to said second end, said optical transmission means coupling a primary reflected laser beam and a secondary reflected laser beam into a combined laser beam including an interference fringe pattern caused by a phase difference between said primary and secondary reflected laser beams, said combined laser beam being transmitted to said first end of said optical coupling transmission means;
interferometric sensing means having first and second ends, for varying an optical path in response to an environmental temperature, said first end of said interferometric sensing means being connected to said second end of said optical coupling transmission means, said interferometric sensing means producing said primary reflected laser beam by reflecting a first portion of said first laser beam at said first end of said interferometric sensing means, said interferometric sensing means further producing said secondary reflected laser beam by reflecting a second portion of said first laser beam on said second end of said interferometric sensing means, said second portion of said first laser beam being a portion of said first laser beam that is not reflected during the production of said primary reflected laser beam, said interferometric sensing means feeding back said primary and secondary reflected laser beams to said second end of said optical coupling transmission means through said varying optical path;
laser detection means for emitting said first laser beam in response to a modulated driving signal, and adjusting a magnitude of said first laser beam in dependence upon a magnitude of a prior combined laser beam fed back through said optically coupling transmission means, said laser detection means generating a sense signal indicative of temperature information in dependence upon a degree of adjustment of the magnitude of said first laser beam;
modulated signal generation means for generating said modulated driving signal in response to a pilot signal;
and
temperature processing means for generating said pilot signal, and converting said sense signal into an indicated temperature.

3 more elements

Dependencies are inferred from the claim text.

Interferometric temperature sensing system having a coupled laser diode wherein the magnitude is adjusted corresponding to a prior feed-back laser beam

Life of this patent

Interferometric temperature sensing system having a coupled laser diode wherein the magnitude is adjusted corresponding to a prior feed-back laser beam

Life of this patent

Abstract

Claims38