AU2020103532A4 - A fiber Mach-Zehnder and a Michelson interferometer array combined measurer - Google Patents

A fiber Mach-Zehnder and a Michelson interferometer array combined measurer Download PDF

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AU2020103532A4
AU2020103532A4 AU2020103532A AU2020103532A AU2020103532A4 AU 2020103532 A4 AU2020103532 A4 AU 2020103532A4 AU 2020103532 A AU2020103532 A AU 2020103532A AU 2020103532 A AU2020103532 A AU 2020103532A AU 2020103532 A4 AU2020103532 A4 AU 2020103532A4
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fiber
array
michelson interferometer
coupler
zehnder
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AU2020103532A
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Jun Yang
Yonggui YUAN
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Harbin Engineering University
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Harbin Engineering University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35383—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using multiple sensor devices using multiplexing techniques
    • G01D5/35396—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using multiple sensor devices using multiplexing techniques using other forms of multiplexing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration
    • G01B9/02023—Indirect probing of object, e.g. via influence on cavity or fibre
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/02056—Passive reduction of errors
    • G01B9/02057—Passive reduction of errors by using common path configuration, i.e. reference and object path almost entirely overlapping
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/0209—Low-coherence interferometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
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    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35303—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using a reference fibre, e.g. interferometric devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
    • G01D5/35309—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer
    • G01D5/35319—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer using other multiple wave interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
    • G01D5/35325—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using interferometer with two arms in reflection, e.g. Mickelson interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
    • G01D5/35329—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using interferometer with two arms in transmission, e.g. Mach-Zender interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/3537—Optical fibre sensor using a particular arrangement of the optical fibre itself
    • G01D5/35374—Particular layout of the fiber
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
    • G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29346—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by wave or beam interference
    • G02B6/29361—Interference filters, e.g. multilayer coatings, thin film filters, dichroic splitters or mirrors based on multilayers, WDM filters
    • G02B6/2937—In line lens-filtering-lens devices, i.e. elements arranged along a line and mountable in a cylindrical package for compactness, e.g. 3- port device with GRIN lenses sandwiching a single filter operating at normal incidence in a tubular package

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  • Optics & Photonics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

The present invention proposes a fiber Mach-Zehnder and a Michelson interferometer array combined measurer. It comprises a broad spectrum light source (1), a photodetector (2), a 3dB fiber 2x2 coupler (3), a fiber Mach-Zehnder interferometer, a transposed 3dB fiber 2x2 coupler (7), fiber Michelson interferometer array (8) and (8'), and a single-mode connection fiber (9). In which, the Mach-Zehnder interferometer consists of an attenuator (4), grin lens (5), a total reflection cube prism (6), and a connection fiber (9). The invention uses simultaneous measurement of strain and temperature technique to achieve the temperature compensation technology and the array set-out by fiber sensors, it enables multiple sensors to achieve absolute measurement without interfering with each other, reducing the cost of single-point measurement and ensuring real-time measurement. At the same time, the fiber materials and devices used are standard fiber communication components, which are low cost, easy to obtain and to promote. 1/1 DRAWINGS F 6 5S FIG.1I

Description

1/1 DRAWINGS
F6
5S
FIG.1I
DESCRIPTION TITLE OF INVENTION
A fiber Mach-Zehnder and a Michelson interferometer array combined measurer
TECHNICAL FIELD
[0001] The invention relates to a measurement device, particularly relates to a fiber
interferometer array measurer that is based on the principle of white light interference.
BACKGROUND ART
[0002] The research and development of fiber interferometry measurement systems with
different types of low coherence light sources (broad spectrum sources, narrow spectrum light
emitting diodes (LEDs), superluminescent diodes (SLEDs) and amplified spontaneous emission
(ASEs), multimode laser diode, etc.) has become a very active field of technology. As a subset of
fiber interferometry, low coherence light source measurement systems have demonstrated many
advantages over other fiber interferometry systems. The most important feature is the ability to
make absolute measurements of the subject. In addition, they offer high resolution and wide
dynamic range, and low system costs due to the low cost of the low coherence sources and
multimode fibers used in the systems. White light interferometry is used to measure a wide range
of physical quantities.
[0003] Among the white light interferometric sensing systems that have already been developed,
there are time division multiplexing (TDM), frequency division multiplexing (FDM), space
division multiplexing (SDM) and other multiplexing technologies. For example, Santos, et al.
(Santos, J.L., Jackson, D.A., Coherence sensing of time-addressed optical-fiber sensors
illuminated by a multimode laser diode Appl. Opti, 30, 5068-5077, 1991) has published the
TDM technology, this is a multiplexing technique for address by using the delay effect of optical
fibers on the light waves. This method is complex, with limited multiplexing numbers, small
measurement range and low accuracy. In addition, Liu, et al. (Liu, T., Fernando, G.F., A
frequency division multiplexed low-finesse optical fiber Fabry-Perot sensor system for strain and
displacement measurements, Review of Scientific Instruments, 71(3), 1275-1278, 2000)
published the FDM technology, which directly measures the multiplied results of optical
spectrum output by multiple Fabry-Perot interferometers with different cavity lengths using a
spectral analyzer. This method is limited by the cavity lengths and cavity length differences, and
the number of interferometers to be multiplexed is limited to a few. However, Yuan, et al. (Yuan,
L.B., Li, Q.B., Liang, Y.J., Fiber optic 2-D sensor for measuring the strain inside the concrete
specimen. Sensors and Actuators A, 94(2001)25-31) has published the SDM, where the multiple
sensors can be easily demodulated and interrogated using the plane mirrors in the reference arm
for spatial continuous optical path scanning, making it easy to realize the two-dimensional strain
measurement. This method has a simple structure and high measurement accuracy, but because
there is only one reference plane, the scanning range of the plane mirror needs to be large, and
when the system contains multiple sensors, due to the attenuation of the reflected signal strength
of the sensing arm, the contrast of the interference signal is poor and the white light interference
signal is weak, so the number of multiplexing of the interferometer is only a few.
[0004] In 2006, the applicant disclosed a multiplexing fiber interferometer and its nesting
construction method (Application No. 200610151043.5), and invented an all-fiber interferometry
fiber and its implementation method that can construct a sensor array and a network, which
solves the problem of multiplexing of fiber interferometers. In the low coherence twisted
Sagnac-like fiber optic deformation sensing device (Application No. 200710072350.9) disclosed
by the applicant in 2007, it is primarily used to solve the problem of damage resistance in the deployment of fiber sensor arrays.
[0005] Fiber sensors have intrinsic responses to strain and temperature, i.e., changes in ambient temperature as well as external stresses cause the sensor output. In multiplexing fiber sensing arrays and networks, especially for the measurement and application of smart structures, strain sensors, whether point or large scale, encounter temperature compensation problems. Hence, the temperature compensation problem is a very important and extremely difficult problem for strain sensing measurements and other fiber sensing measurements.
SUMMARY OF INVENTION
[0006] It is an object of the present invention to propose a fiber Mach-Zehnder and a Michelson interferometer array combined measurer that enables multipoint array measurement without mutual interference.
[0007] The objective of the invention is achieved by the followings:
[0008] It consists of a broad spectrum light source 1, a photodetector 2, a 3dB fiber 2x2 coupler 3, a fiber Mach-Zehnder interferometer, a transposed 3dB fiber 2x2 coupler 7, fiber Michelson interferometer arrays 8 and 8'. In which, thefiber Mach-Zehnder interferometer consists of an attenuator 4, grin lens 5, a total reflection cube prism 6, and a connection fiber 9. The spectrum emitted from the broad spectrum light source 1 is injected through the adapter into the optical fiber, enters the 3dB optical fiber 2x2 coupler 3, the two beams of light out of the 3dB optical fiber 2x2 coupler 3 go into the two arrays of the optical fiber Mach-Zehnder interferometer, respectively. The light from these two arrays goes through the transposed 3dB optical fiber 2x2 coupler 7 and are directionally coupled into the fiber Michelson interferometer arrays 8 and 8'.
The array 8 is the reference array, and the array 8' is the sensing array. A beam of light returned
from the reflective end face of the reference array 8 is then coupled into the photodetector 2
through the transposed 3dB fiber 2x2 coupler 7 and the attenuator 4, this is the reference signal
light. Another light returning from the reflective end face of the sensing array 8' passes through
the transposed 3dB fiber 2x2 coupler 7, the grin lens 5, the total reflection cube prism 6, and the
photodetector 2 to become the modulated measurement signal light.
[0009] The invention can also include:
[0010] 1. The Michelson interferometer array is composed of a series offiber reflective end
faces 8 and 8' having a certain reflectivity, and these fiber reflective end faces 8 and 8' form the
two arms of the fiber Michelson interferometer as the reference array and the sensing array,
respectively. The fiber sensors on the same array are closely connected to each other by fiber
connectors, each fiber segment is coded sequentially, each fiber segment on the reference array
is of equal length, and the length of each fiber segment on the sensing array is increased or
decreased sequentially.
[0011] 2. The Michelson interferometer array is composed of a series offiber reflective end
faces having a certain reflectivity, and these fiber reflective end faces form the two arrays of the
fiber Michelson interferometer as the reference array and the sensing array, respectively. The
fiber sensors on the same array are closely connected to each other by fiber connectors, each
fiber segment is coded sequentially, and the length of each fiber segment is increased or
decreased sequentially, each corresponding fiber segment on different arrays is of equal length.
[0012] The basic principle of the invention is based on the principle of white light interference
and SDM. The spectrum emitted from the low coherent broad spectrum light source 1 is injected
through the adapter into the optical fiber, then split into two beams by the 3dB optical fiber 2x2 coupler 3 and go into the two arms of the optical fiber Mach-Zehnder interferometer, respectively. The light from these two arms go through the transposed 3dB optical fiber 2x2 coupler 7 and are directionally coupled into the fiber Michelson interferometer arrays 8 and 8'.
The array 8 is the reference arm, and the array 8' is the sensing arm. A beam of light returned
from the reflective end face of the reference array 8 is then coupled into the photodetector 2
through the transposed 3dB fiber 2x2 coupler 7 and the attenuator 4, this is the reference signal
light. Another light returning from the reflective end face of the sensing array 8' passes through
the transposed 3dB fiber 2x2 coupler 7, the grin lens 5, and the total reflection cube prism 6, and
also arrives at the photodetector 2 to become the modulated measurement signal light. The
reference and measurement signal light interfere on the surface of the photodetector, due to the
extremely short coherence length of the low coherence light source, about several micrometers to
several tens of micrometers, the interference phenomenon will only occur when the optical path
difference between the reference signal light and the measurement signal light is almost equal,
and a white light interference pattern is seen. The white light interference pattern is characterized
by a primary maximum known as the zero-level central interference strip. It corresponds to the
position where the optical paths of the reference signal light and the measured signal light are
equal. By adjusting the position of the total reflection angle cube prism 6, it is possible to
equalize the optical paths of the reference and measurement signal light and obtain a central
interferometric strip. This central interferometric strip provides an initial reference position for
the measurement. When the change in the quantity to be measured causes a change in the optical
path of the measured signal, we can obtain the absolute value of the change of quantity to be
measured from the change in the position of the central interferometric strip by simply scanning
the total reflection cube prism 6.
[0013] In order to realize the SDM, fiber Michelson interferometer arrays 8 and 8' are designed,
with a certain length of sensing arm or reference arm between each reflective end face, the length
of the sensing arms and reference arms are set to ensure that the interference strips are
independent of each other and do not interfere with each other, but can be scanned through the
spatial optical path scanning of the total reflection cube prism 6, to distinguish between multiple
sensors, and to achieve interrogation and measurement on multiple quantities to be measured.
This technique of separating the central interferometric strips of multiple sensors from each other in the optical path scanning space is called SDM.
[0014] The basic idea of the construction of white light fiber interferometer based on SDM is that the optical paths introduced by the measurement beam through the different measurement optical paths or sensors can be matched one to one by scanning the optical paths of the reference beam, so that the resulting white light interferometric strips are independent of each other in the optical path scanning space and they do not interfere with each other. The splitting of the measurement beam can be achieved by adding reflective surfaces to the optical fiber, and the matching of the reference beam can be achieved directly by using a continuously variable optical delay line to scan the optical path.
[0015] The strain measurement of fiber optic sensors is inevitably affected by changes in ambient temperature because the response of the sensor to strain and temperature is intrinsic. Therefore, in the measurement and application of smart structures, one of the most difficult problems for strain sensors, whether point or large scale, is how to eliminate the influence of ambient temperature, i.e., temperature compensation problems. The invention uses the twin sensor array to eliminate the temperature influences during the measuring process, the basic idea is that the measurement arm and the reference arm are placed close to each other in the environment to be measured, and the reference arm is isolated from the environment to be measured. The measurement arm senses both the strain and the ambient temperature, and the reference arm senses only the temperature, i.e., the temperature has the same effect on the reference arm and the measurement arm. In this way, although the length changes of the fiber optic sensors in the measurement arm is related to both temperature and strain, the length of the fiber optic sensor in the reference arm affected by temperature is the same as that of the measurement arm, so that when the measurement light interferes with the reference light, the effect of temperature is eliminated, i.e., the change of the peak white light interference is only related to the magnitude of the strain, and the corresponding strain value can be calculated from the value of the peak offset to realize the measurement.
[0016] The advantages and features of the invention are:
[0017] 1. The present invention is a method to solve the multiplexing problem of white light
fiber interferometer, which realizes the arraying of fiber optic sensors so that multiple sensors
can achieve absolute measurement without interfering with each other, reducing the cost of
single point measurement and ensuring real-time measurement. At the same time, interrogation
and measurement of multiple sensors can be achieved using only the spatial continuous scanning
of a full reflection cube prism. Due to the arraying of the reference arm and the reasonable use of
attenuator, the spatial scanning range of the total reflection cube prism is significantly reduced,
while the system multiplexing number can be significantly increased, and the technology is
simple and easy to implement.
[0018] 2. The fiber optic materials and devices used in the present invention are standard fiber
optic communication components, which are inexpensive, readily available, and conducive to
promote.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a schematic diagram of the structure of present invention.
DESCRIPTION OF EMBODIMENTS
[0020] The invention is further described below in connection with the drawing:
[0021] In conjunction with the drawing, the first embodiment method of a fiber Mach-Zehnder and a Michelson interferometer array combined measurer consists of: a broad spectrum light source 1, a photodetector 2, a 3dB fiber 2x2 coupler 3, a fiber Mach-Zehnder interferometer, a transposed 3dB fiber 2x2 coupler 7, fiber Michelson interferometer arrays 8 and 8', and a single mode connection fiber 9. In which, thefiber Mach-Zehnder interferometer consists of an attenuator 4, grin lens 5, a total reflection cube prism 6, and a connection fiber 9. The spectrum emitted from the broad spectrum light source 1 is injected through the adapter into the optical fiber, enters the 3dB optical fiber 2x2 coupler 3, the two beams of light out of the 3dB optical fiber 2x2 coupler 3 go into the two arms of thefiber Mach-Zehnder interferometer, respectively. The light from these two arms goes through the transposed 3dB optical fiber 2x2 coupler 7 and are directionally coupled into the fiber Michelson interferometer arrays 8 and 8'. The array 8 is the reference arm, and the array 8' is the sensing arm. A beam of light returned from the reflective end face of the reference array 8 is then coupled into the photodetector 2 through the transposed 3dB fiber 2x2 coupler 7 and the attenuator 4, this is the reference signal light. Another light returning from the reflective end face of the sensing array 8' passes through the transposed 3dB fiber 2x2 coupler 7, the grin lens 5, the total reflection cube prism 6, and the photodetector 2 to become the modulated measurement signal light. The Michelson interferometer array is composed of a series of fiber reflective end faces 8 and 8' having a certain reflectivity, and these fiber reflective end faces 8 and 8' form the two arms of the fiber Michelson interferometer as the reference array and the sensing array, respectively. The fiber sensors on the same array are closely connected to each other by fiber connectors, each fiber segment is coded sequentially, each fiber segment on the reference array is of equal length, and the length of each fiber segment on the sensing array is increased or decreased sequentially. With this length parameter setting, the initial position of each sensor can be easily determined by appropriately adjusting the attenuator and the spatial continuous scan of the total reflection cube prism, and the initial positions of each sensor are equally spaced between each other, with the spacing value being half of the difference in length between adjacent fiber segments. Afterwards, the length change of any fiber segment on the sensing array can be interrogated and measured in absolute discrete by simply using the spatial continuous scanning of the total reflection cube prism.
[0022] The second embodiment method includes the basic composition of the first embodiment method, the difference is that: the Michelson interferometer array is composed of a series offiber reflective end faces having a certain reflectivity, and these fiber reflective end faces form the two arrays of the fiber Michelson interferometer as the reference array and the sensing array, respectively. The fiber sensors on the same array are closely connected to each other by fiber connectors, each fiber segment is coded sequentially, and the length of each fiber segment is increased or decreased sequentially, each corresponding fiber segment on different arrays is of equal length. This embodiment differs from the first due to the different shear forms of the fiber segments in the reference and sensing arrays, and the different starting point of the first sensor and the different parameters of the attenuator during calibration.

Claims (3)

1. A fiber Mach-Zehnder and a Michelson interferometer array combined measurer, consisting of a broad spectrum light source (1), a photodetector (2), a 3dB fiber 2x2 coupler (3), a fiber Mach-Zehnder interferometer, a transposed 3dB fiber 2x2 coupler (7), a first fiber Michelson interferometer array (8) and a second fiber Michelson interferometer array (8'). Its characteristics are: the fiber Mach-Zehnder interferometer consists of an attenuator (4), grin lens (5), a total reflection cube prism (6), and a connection fiber (9). The spectrum emitted from the broad spectrum light source (1) is injected through the adapter into the optical fiber, enters the 3dB optical fiber 2x2 coupler (3), the two beams of light out of the 3dB optical fiber 2x2 coupler (3) go into the two arrays of the optical fiber Mach-Zehnder interferometer, respectively. The light from these two arrays goes through the transposed 3dB optical fiber 2x2 coupler (7) and are directionally coupled into the first fiber Michelson interferometer array (8) and the second fiber Michelson interferometer array (8'). The first fiber Michelson interferometer array (8) is a reference array, and the second fiber Michelson interferometer array (8') is a sensing array. A beam of light returned from the reflective end face of thefirstfiber Michelson interferometer array (8) is then coupled into the photodetector (2) through the transposed 3dB fiber 2x2 coupler (7) and the attenuator (4), this is the reference signal light. Another light returning from the reflective end face of the second fiber Michelson interferometer array (8') passes through the transposed 3dB fiber 2x2 coupler (7), the grin lens (5), the total reflection cube prism (6), and the photodetector (2) to become the modulated measurement signal light.
2. As claimed in claim 1, a fiber Mach-Zehnder and a Michelson interferometer array combined measurer, its characteristics are: the Michelson interferometer array is composed of a series of fiber reflective end faces having a certain reflectivity, and these fiber reflective end faces form the two arrays of the fiber Michelson interferometer as the reference array and the sensing array, respectively. The fiber sensors on the same array are closely connected to each other by fiber connectors, each fiber segment is coded sequentially, each fiber segment on the reference array is of equal length, and the length of each fiber segment on the sensing array is increased or decreased sequentially.
3. As claimed in claim 1, a fiber Mach-Zehnder and a Michelson interferometer array
combined measurer, its characteristics are: the Michelson interferometer array is composed of a
series of fiber reflective end faces having a certain reflectivity, and these fiber reflective end
faces form the two arrays of the fiber Michelson interferometer as the reference array and the
sensing array, respectively. The fiber sensors on the same array are closely connected to each
other by fiber connectors, each fiber segment is coded sequentially, and the length of each fiber
segment is increased or decreased sequentially, each corresponding fiber segment on different
arrays is of equal length.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113411695A (en) * 2021-06-28 2021-09-17 中山水木光华电子信息科技有限公司 Communication method and system with optical cable identification code and information code

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113411695A (en) * 2021-06-28 2021-09-17 中山水木光华电子信息科技有限公司 Communication method and system with optical cable identification code and information code

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