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WO2008100266A2 - Microphone à fibre optique mems - Google Patents

Microphone à fibre optique mems Download PDF

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Publication number
WO2008100266A2
WO2008100266A2 PCT/US2007/011954 US2007011954W WO2008100266A2 WO 2008100266 A2 WO2008100266 A2 WO 2008100266A2 US 2007011954 W US2007011954 W US 2007011954W WO 2008100266 A2 WO2008100266 A2 WO 2008100266A2
Authority
WO
WIPO (PCT)
Prior art keywords
diaphragm
microphone
fiber
fiber optic
endface
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2007/011954
Other languages
English (en)
Other versions
WO2008100266A3 (fr
Inventor
Ken K. Chin
Guanhua Feng
Harry Roman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
New Jersey Institute of Technology
Original Assignee
New Jersey Institute of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by New Jersey Institute of Technology filed Critical New Jersey Institute of Technology
Publication of WO2008100266A2 publication Critical patent/WO2008100266A2/fr
Anticipated expiration legal-status Critical
Publication of WO2008100266A3 publication Critical patent/WO2008100266A3/fr
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
    • G01L9/0076—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means
    • G01L9/0077—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means for measuring reflected light
    • G01L9/0079—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means for measuring reflected light with Fabry-Perot arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R23/00—Transducers other than those covered by groups H04R9/00 - H04R21/00
    • H04R23/008—Transducers other than those covered by groups H04R9/00 - H04R21/00 using optical signals for detecting or generating sound
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2410/00—Microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H04R31/006—Interconnection of transducer parts

Definitions

  • This invention involves the design and fabrication of a new Fabry-Perot diaphragm- fiber optic microphone by using MEMS technology in processing and packaging.
  • the currently described microphone permits direct amplification of audible signal without requiring modulation or demodulation.
  • Fiber optic microphones have been proposed [1 -3] however, they are non-functional or ineffective because they are either interference based, utilizing a piece or coil of optical fiber as the sensing element, or intensity based, using a diaphragm as the pressure wave sensing element. Sensors with diaphragm-fiber for acoustic signal sensing or pressure sensing, especially under high temperature, were inaccurately reported as Fabry-Perot type interferometer devices.
  • the present invention is a Fabry-Perot diaphragm fiber optic microphone, which was fabricated with MEMS (micro electric mechanical system) technology.
  • the microphone contains a diaphragm which is clamped to the ferrule of the single mode fiber.
  • the diaphragm structure may contain three thicknesses which control various frequency responses.
  • the inner area can be embossed to minimize the interference gap width between the diaphragm and the fiber endface as well as ensure proper alignment between the fiber and the diaphragm.
  • FIG. 1 is a drawing illustrating the design of a broadband Fabry-Perot Diaphragm- Fiber Optic Microphone.
  • FIG. 3 is a micrograph of the diaphragm of a MEMS Fiber Optic Microphone.
  • FIG. 4 a graphical representation of the static measurement of output optic intensity as a function of pressure. The pressure is in units of centimeter of water column, and the optical output power is in arbitrary units.
  • FIG. 5 represents the frequency response of the microphone with 2 ⁇ thick diaphragm and 5 ⁇ gap.
  • V FPo the maximum of output voltage of the DFOS n refractive index of the medium; for air n ⁇ 1 ⁇ wavelength of the light used for the DFOS
  • Patm the atmospheric pressure P 0 the maximum pressure of the acoustic wave
  • V 2 the final air volume of the cavity or at the backside of the diaphragm after the DFOS is immersed in the liquid p the density of the liquid the DFOS is immersed in g gravitational acceleration, ⁇ 9.8 m/s 2 h the depth of the liquid
  • NA numerical aperture of the fiber ⁇ beam angle of spreading of the Gaussian beam w 0 waist of the Gaussian beam z 0 Rayleigh length of the Gaussian beam R wave front radius of the Gaussian beam rif refractive index of the core of the step-index fiber n c refractive index of the cladding of the step-index fiber
  • the present invention is a Fabry-Perot diaphragm fiber optic microphone, which was fabricated with MEMS (micro electric mechanical system) technology.
  • FIG. 1 is one embodiment of the overall structure of the microphone.
  • diaphragm 102 is clamped to the stainless steel ferrule 104 of the single mode fiber 106 (which is enclosed by zinconia ferrule 107) by a washer 108, disk spring 110, and window cap 1 12.
  • the detailed structure of the three thicknesses of the diaphragm is shown in FIG. 2 (and a side view, FIG. 2A).
  • the outer area 3.4 mm x 3.4 mm (the length of one edge of the outer area is indicated by a') is responsible for higher frequency response.
  • the middle area 1.9 mm x 1.9 mm is extremely thin (one edge of the middle area is indicated by b), only 2 ⁇ thick (see thickness t in FIG. 2A), where the diaphragm's intrinsic frequency is about 150 Hz.
  • the center square of 350 ⁇ x 350 ⁇ is the embossed center to keep the interference gap width between the diaphragm and the fiber endface as small as 5 ⁇ . The embossed center also helps keep the fiber and diaphragm properly aligned.
  • FIG. 3 is the optical micrograph of the diaphragm of this embodiment of the MEMS Fabry-Perot fiber optic microphone. Note that the 2 ⁇ thick middle area 302 is transparent. Multiple light sources are compatible with the present invention. One embodiment includes using a DFB single mode laser. Another embodiment uses a lower cost light emitting diode (LED) as the light source.
  • LED light emitting diode
  • F is the finesse, defined by
  • V j(o) , j(o) ( 6 )
  • a is a constant depending on the shape and boundary conditions of the plate or diaphragm, being 0.00126 for square shape and 0.000977
  • b the lateral size of the edge clamped diaphragm
  • D the flexural rigidity of the diaphragm
  • h is the thickness of the diaphragm, E Young's modulus, and v Poisson coefficient of the diaphragm material.
  • Si (IOO) Poly Si SiO 2 Quartz Amo ⁇ h. SiO 2
  • the intrinsic fundamental mode frequency of the diaphragm is [3]
  • ⁇ is the eigen value depending on the shape and boundary condition of the diaphragm
  • b the lateral size of the diaphragm
  • p p the plate mass density, equal to ph
  • p being the density of material of the plate. Therefore
  • the thickness of the diaphragm can be varied while keeping the lateral size a constant so that the same mask set can be used. Therefore, the frequencies of the fundamental and higher order modes of the diaphragm can meet the need.
  • the experimental results of frequency response for this embodiment are as shown in FIG. 5.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Spectrometry And Color Measurement (AREA)

Abstract

L'invention concerne la théorie, la conception, la fabrication et la caractérisation d'un microphone à fibre optique à diaphragme de type Fabry-Perot MEMS (système micro électromécanique). En utilisant la technologie MEMS dans le traitement et le conditionnement, un carré de 1,9 mm x 1,9 mm, un diaphragme de SiO<SUB>2</SUB> de 2 µ d'épaisseur avec un centre gaufré de 350 µ carrés de silicium est mécaniquement verrouillé sur la virole d'une fibre à mode unique pour maintenir sa proximité (5 µ) et son orientation perpendiculaire par rapport au diaphragme. Une mesure statique de puissance de sortie optique par rapport à la pression sur la membrane révèle plus d'une période d'interférence de type Fabry-Perot, générant ainsi un dispositif d'interféromètre à fibre à diaphragme de type Fabry-Perot reproduisant de manière précise une onde acoustique sonore.
PCT/US2007/011954 2006-05-19 2007-05-18 Microphone à fibre optique mems Ceased WO2008100266A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US80194306P 2006-05-19 2006-05-19
US80191006P 2006-05-19 2006-05-19
US60/801,910 2006-05-19
US60/801,943 2006-05-19

Publications (2)

Publication Number Publication Date
WO2008100266A2 true WO2008100266A2 (fr) 2008-08-21
WO2008100266A3 WO2008100266A3 (fr) 2009-02-26

Family

ID=39690640

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2007/011954 Ceased WO2008100266A2 (fr) 2006-05-19 2007-05-18 Microphone à fibre optique mems

Country Status (1)

Country Link
WO (1) WO2008100266A2 (fr)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5621372A (en) * 1979-07-31 1981-02-27 Fujitsu Ltd Manufacture of semiconductor device
US4933545A (en) * 1985-12-30 1990-06-12 Metricor, Inc. Optical pressure-sensing system using optical resonator cavity
DE19623504C1 (de) * 1996-06-13 1997-07-10 Deutsche Forsch Luft Raumfahrt Optisches Mikrophon
CN1201631C (zh) * 1997-11-19 2005-05-11 福田三恭司 扬声器系统
US6351593B1 (en) * 1998-11-30 2002-02-26 Three E Laboratories, Inc. Hermetically sealed connectors and feed-throughs for fiber optic cables and method for effecting hermetic seals for such cables
KR100512960B1 (ko) * 2002-09-26 2005-09-07 삼성전자주식회사 플렉서블 ｍｅｍｓ 트랜스듀서와 그 제조방법 및 이를채용한 플렉서블 ｍｅｍｓ 무선 마이크로폰
US7428054B2 (en) * 2002-10-15 2008-09-23 University Of Maryland Micro-optical sensor system for pressure, acceleration, and pressure gradient measurements

Also Published As

Publication number Publication date
WO2008100266A3 (fr) 2009-02-26

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