WO1992018886A1 - Aiguillage optique photoelastique, systemes optiques l'utilisant, et procede d'utilisation - Google Patents

Aiguillage optique photoelastique, systemes optiques l'utilisant, et procede d'utilisation Download PDF

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Publication number
WO1992018886A1
WO1992018886A1 PCT/US1991/002773 US9102773W WO9218886A1 WO 1992018886 A1 WO1992018886 A1 WO 1992018886A1 US 9102773 W US9102773 W US 9102773W WO 9218886 A1 WO9218886 A1 WO 9218886A1
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WO
WIPO (PCT)
Prior art keywords
optical
switch
photoelastic
transparent
optical switch
Prior art date
Application number
PCT/US1991/002773
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English (en)
Inventor
George Seaver
Original Assignee
George Seaver
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 George Seaver filed Critical George Seaver
Priority to PCT/US1991/002773 priority Critical patent/WO1992018886A1/fr
Publication of WO1992018886A1 publication Critical patent/WO1992018886A1/fr

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Classifications

    • 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
    • G01D5/268—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 using optical fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0128—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects
    • G02F1/0131—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/31—Digital deflection, i.e. optical switching
    • G02F1/313—Digital deflection, i.e. optical switching in an optical waveguide structure
    • G02F1/3131—Digital deflection, i.e. optical switching in an optical waveguide structure in optical fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/07—Polarisation dependent

Definitions

  • optical switches are: expanded beam/rotating mirror? moving fiber; polarized beam magnetic rotator; traveling acoustic wave; polarized beam liquid crystal rotator; and an electrically operated Lithium Niobate waveguide; while electrically operated organic polymer waveguides are under development. It is therefore desirable to provide an optical switch, and optical systems employing the optical switch, and a method of optically switching an optical beam from a one to another position to overcome some or all of the disadvantages of the prior art optical switches.
  • an optical switch which compared with the state of the art switches is simpler and cheaper and usually with lower losses and crosstalk, and which can be used in single or multimode beams, and which can operate over a wide wavelength range, and is solid state, and is environmentally rugged, and is or can be made temperature insensitive.
  • the optical switch of the invention is obtained by applying an inhomogeneous stress field to an optically transparent photoelastic material that propagates an optical beam.
  • the non-uniform refractive index distribution thus formed creates a gradient index that changes the direction of propagation and, subsequently, the output position or angle of the optical beam traveling through the material.
  • the inhomogeneous character of the stress field must be negligible, and the stress gradient must be smaller than the stress anisotropy.
  • the present invention relates to a photoelastic optical switch, to optical systems employing the optical switch, and to a method of optically switching an optical beam path fror one to another position in a simple, easy and effective manner.
  • the optical switch of the invention comprises an optical switch for altering and changing the path of an optical bear- or beams from one to another position and which optical switch comprises a photoelastic optically transparent material which is in slab or fiber form whose index of refraction changes with mechanical stress and which optically transparent material has an inlet window adapted to receive an optical beam from an optical source and an outlet window adapted to pass an optical beam from the optically transparent material to an optical receptor, the optically transparent material permitting the optical beam to pass between the inlet window and the outlet window.
  • the optical switch also comprises means, such as electrical or mechanical means, to apply a predetermined force or bending moment to the photoelastic, optically transparent material in order to form a stress gradient in said photoelastic material, which stress gradient changes the index of refraction of said material so as to form an index of refraction gradient within the material which alters the path of the optical beam passing through the optical material, and therefore changes the beam in the outlet window from an unstressed, normal optical beam path to a stressed, bent optical beam path, thereby providing for a change in position and/or angle between the stressed and unstressed optical beam paths.
  • means such as electrical or mechanical means
  • the invention comprises also an optical system which includes the optical switch and which includes one or more optical beam sources to provide for one or more optical beams to be placed on the inlet window and which includes optical receptors or non-receptors or a combination of receptors and non-receptors positioned to receive or not to receive in an optimum manner an optical beam emerging from the outlet window.
  • the method includes the method of switching one or more optical beams between the first and second outlet position, which method comprises providing an optically transparent photoelastic material with an index- of refraction changing with stress and having an inlet window and an outlet window and introducing an optical beam into the inlet window from an optical source, passing an optical beam from the outlet window to an optical receptor or non-receptor and applying a predetermined bending moment or force to the photoelastic optically transparent material to form a stress gradient within the optically transparent photoelastic material which changes the index of refraction to form an index of refraction gradient, thereby switching the optical beam issuing from the outlet window between a zero stress and a stressed beam position or angle and thereby providing for the optical switching of an optical beam between a first and second position.
  • the optical switch is dependent upon which photoelastic optical material is used to fabricate the switch, particularly the slab portion. In one embodiment both polarizations are switched, whereas, in another, only one polarization is switched. The difference lies in the molecular physics of the materials used and the resultant degree of anisotropy of the local stress field. If materials such as quartz or polycarbonate plastic are used as the optical material, only the polarized component parallel to the stresses are switched. If plexiglass, i.e. acrylic, or styrene plastic is used, both polarizations are switched.
  • the important parameters of the optical switch are the switch material, e.g. quartz, plexiglass, polystyrene, polycarbonate, the applied stress, and particularly the switch thickness, d.
  • the photoelastic optically transparent material can be in a variety of forms, but typically is in the preferred slab-type form, either square or rectangular, with the stress applied simply by finger pressure or by mechanical levers or by- piezoelectric or other techniques to apply a bending moment to the optically transparent photoelastic material. Por example, one method of applying this stress is piezoelectrically. Two thin plates of quartz of opposite piezoelectric polarity sandwich the photoelastic material, and when electrically activated, a bending moment and stress gradient is imposed on the switch. This approach has the added advantage of a potential megahertz response rate, depending upon the switch material and size.
  • the optical switch may be employed in a variety of optical systems. By using appropriate shaped switches and other means, such as point forces, to concentrate and shape the stresses, various stress fields and beam displacements can be realized.
  • an optical lens whose focal properties and focal axis are made variable by varying the applied forces.
  • Solid state switching of large multimode beams is possible and specifically, the optical switch can be used to provide default routes in a fiberoptic local area network. It can also be used to sense bending stress in a material, such as in a pressure window in an underwater vehicle. This can be accomplished by measuring the ratio of the intensities of the signals in the "on" and "off” switch output ports as the beam is deflected from one to the other.
  • the switch can also be used to normalize a sensor that operates with a polarized input, such as a photoelastic birefringent pressure sensor, by an on-command removal of the first polarizer in order to provide a reference signal output.
  • Fig. 1 is a schematic, illustrative view of the basic optical switch of the invention
  • F g. 2 is a schematic, illustrative view of the optical switch of Fig. 1 in an optical system providing a back-up optical fiber transmission line for a communications system?
  • Fig. 3 is a schematic, illustrative view of the optical switch of Fig. 1 in an optical system which allows two-way communication on a single optical fiber;
  • Fig. 4 is a schematic, illustrative view of the optical switch, of Fig. 1 that permits normal and by-pass configuration for terminals in a fiberoptic local area network
  • Fig. 5 is a schematic, illustrative view of the optical switch of Fig. 1 in an optical system which allows several sensors to be serviced by a single optical fiber;
  • Fig. 6 is a schematic, illustrative view of the optical switch of Fig. 1 in an optical system when operated as a polarizing switch by using fused quartz as the photoelastic material;
  • Fig. 7 is a schematic, illustrative view of the optical polarizing switch of Fig. 6 used to normalize a photoelastic birefringent pressure sensor when the switch is in the "off” position and to allow sensing when in the "on” position;
  • Fig. 8 is a schematic, illustrative view of the optical switch of Fig. 1 when employed as a pressure and bending stress sensor;
  • Fig. 9 is a schematic, illustrative view which shows a method of applying a bending moment to the optical switch of Fig. 1 and which finger pressure* changes the bending moment of the swtich from concave to convex or the reverse;
  • Fig. 10 is a schematic, illustrative view of an optical switch in a system to compensate the optical switch for temperature changes;
  • Fig. 11 is a schematic, illustrative view of an optical switch of the invention when the stress is applied by piezoelectri ⁇ techniques.
  • FIG. 1 shows an optical switch 10 comprising a generally rectangular slab of photoelastic transparent material 12, such as plexiglass, having an inlet window 14 at the one end and an outlet window 16 at the other and opposite end.
  • An optical beam guided in an optical fiber 18 is incident on the inlet window and passes through the optical material 12 and out an outlet window 16 and such path is known as the normal, unstressed optical beam 20.
  • the bending moment M is applied to the optical material 12 to create a gradient stress and gradient index of refracti ' on within the material 12 so as to provide for the movement of the normal, unstressed optical beam 20 to a stressed optical beam 22 as illustrated in Fig. 1.
  • the optical material 12 may comprise a one-inch wide, two-inch long, one-eighth inch thick plexiglass plate material that is subject to a bending induced stress from finger pressure and will produce an angular beam' displacement of about two degrees experimentally or about two beam diameters at the outlet window,16 as illustrated in Fig. 1.
  • a one-inch wide, one millimeter thick optically transparent quartz plate that is subject to a bending induced stress of 3700 psi has an angular beam displacement from the normal unstressed path of about one degree experimentally.
  • Figs. 2-5 show various applications of the optical switch of the invention as illustrated in Fig.l in the fields of fiberoptic telemetry and communications.
  • the optical switch can be operated locally and manually or by electrically operated solenoids or piezoelectric plates controlled locally or at a central computer station.
  • the optical systems illustrated in Fig. 2 are applications of fiberoptic transmission links where it is desirable to have a back up or fallback line wherein the optical switch is employed.
  • FIG. 2 illustrates a system which employs an optical transmitter TX transmitting an optical beam to a switch 10 which then directs the beam to a main or a back up transmission line and then through a coupler CP R, and hence to a receiver RX with the optical switch providing for the transmitter to move between the main -8- and the back up line as desired, such selection accomplished by applying a bending moment to the optical switch to provide for a zero stress or a stressed optical beam path.
  • Fig. 3 illustrates a bi-directional optical communications system which shows two optical switches 10 connected to a single fiber line so as to allow bi-directional communications by initially configuring the switches so that an electric-to-optic transmitter E/0 is coupled to one end and an optical-to-electrical 0/E receiver is coupled to the other end; then both switches are changed to the stressed condition whereby the first end is now an O/E receiver and the other end becomes an E/0 transmitter.
  • Fig. 4 is a schematic illustration of by-pass switching in a token-ring local area- network employing optical fiber communications.
  • the optical switch 10 in the token ring allows normal and by-pass configurations of the individual terminals. In the by-pass mode, the terminal is removed from the optical loop.
  • This bypass or "crossback" configuration is achieved by using two optical switches, such as those illustrated in Fig. 1, with the "on" fiber of the first switch coupled to the "off" fiber of the second switch and "on" fiber of the second switch coupled to the "off" fiber of the first switch.
  • Fig. 5 is a schematic illustration of an optical syster which shows the optical switch 10 of Fig. 1 employed in an optical system with four instead of two output fibers, which switch is used to couple a light source and a detector to four optical sensors in a sequential manner based upon the amount of bending moment applied to the optical switch 10.
  • Fig. 6 is a schematic, illustrative view of an optical switch 30 of the invention shown in Fig. 6(a) in the unstressed condition and composed of a fused quartz plate material 32 having an input fiber 34 and with a randomly polarized, unstressed beam path output 36. Shown in Fig. 6(b) is the optical switch 30 in a stressed condition with the randomly polarized beam input 34 wherein the stress gradient deflects the horizontal polarization of the beam to output path 40 and allows the vertical polarization to pass through virtually undeflected to output path 38.
  • Fig. 7 is a schematic, illustrative view of a photoelastic, birefingent pressure sensor employing the polarization optical switch 30 of Fig. 6.
  • the switch 30 acts as a polarizer to the input beam 34 to the pressure sensor and, with a conventional polarizer after it, the sensor then measures the pressure external to the sensor.
  • Fig. 7(a) shows the sensor in a reference state, where Fig. 7(b) shows the sensor in a measurement state.
  • the polarizer switch 30 is unstressed and in an "off" position so that with the first polarizer absent, the beam passes through the sensor unaffected- by pressure.
  • Fig. 7(b) shows a photoelastic birefringent pressure sensor in the measurement condition with the optical switch stressed, and the output beam 38 to the pressure sensor now polarized.
  • FIG. 8 is a schematic, illustrative view wherein the optical switch itself is used as a pressure and bending stress sensor, and the "on" and “off” outlet fibers on the outlet window- are placed close enough together so that the output intensity continuously decreases in the "off” or upper fiber as the intensity in the "on” or lower fiber continuously increases along with the pressure and bending stress, and the ratio of "on” to "off” fiber intensities gives a drift-free and sensitive measure of pressure.
  • Fig. 8(a) shows the switch in a zero pressure state while Fig. 8(b) shows the switch in a elevated pressure state.
  • Fig. 9 is an illustrative, schematic view of a manually operated photoelastic optical switch of the invention 50 wherein Fig. 9(a) is a side view of the switch in the "on” position, and Fig. 9(b) is a top view of the switch in the "on” position. Fig. 9(c) is a side view of the switch in the "off” position, and Fig. 9(d) is a top view of the switch in the "off” position.
  • Fig. 9 shows a casing 48 for a snap-actuated optical swtich and shows the optical switch 50 having a photoelastic transparent material 52 in a casing 48 and having two output fibers 54 and
  • Fig. 9 shows a manual method of applying the bending moment to the photoelastic transparent material 0 52 of an optical switch in which finger pressure alters the bending from concave to convex or the opposite, thereby reversing the bending stress from tension to compression or from compression to tension.
  • the optical switch switches the beam of the input fiber 58 to the output fiber 54 or to 5 56; this actuation technique is the familiar cricket-typs technique found in children's toys.
  • Fig. 10 is a schematic, illustrative view of an optical system which illustrates a remotely operated solenoid method of applying a bending moment to an optical switch which is G compensated for temperature changes.
  • Fig. 10 shows a syster-
  • the photoelastic material 62 made of plexiglass has a photoelastic constant C in equation 2 that changes about one percent per degree centigrade.
  • Fig. 10 illustrates a temperature compensation technique in which the arm 70 expands with temperature to apply an increasing displacement or force and bending stress to the optical switch 62 with increasing temperature.
  • the increase in stress on the photoelastic material 62 is designed to compensate exactly for the decrease in the constant C caused by the increase in temperature thereby providincr for a temperature-compensated optical switch.
  • Fig. 11 is a schematic, illustrative view of a piezoelectric operated optical switch of the invention 80 showing the switch in the "off” or unstressed position in solid lines and in the "on” or stressed position in dotted lines, and wherein the switch includes a pair of piezoelectric thin plates 84, for example of quartz of opposite piezoelectric polarity, applied on either side of the photoelastic transparent material 82.
  • These piezoelectric plates provide, on the application of an electrical voltage from the source 86, a tension-compression bending moment to the photoelastic material 82, and thereby cause the transparent material to move from an "off", zero stress position to an "on", stressed position.
  • the piezoelectrically-operated switch 80 operates by electrically expanding the top piezoelectric plate 84 and contracting the bottom plate 84 so that the bending moment is applied to the optical switched material 82.
  • This bending moment can be reversed at a rate of kilohertz to megahertz depending upon switch material and size.
  • the resultant strain causes the index of refraction, that is, the speed of light in that material, to change. It is made smaller (light speed is increased) under tension, and larger under compression.
  • a bending condition such as is shown in Fig. 1 , the upper part of the material is under tension, and the lower part is under compression.
  • an optical beam or wave propagates through this stress field, then the upper part of the wave front travels faster than the lower part, and the wave front pivots and heads off at an angle to its original direction, as shown in Fig. 1.
  • the degree of directional change is dependent upon the relation between the index change and the applied stress (the photoelastic constant, C), the applied force and bending moment, and the distance over which the stress and index change (the thickness of the material).
  • An optical wave has two polarizations, each perpendicular to the other and to the direction of travel of the wave. Ir. some materials, such as plexiglass and polystyrene plastic, both polarizations are deflected by the stress and index cf refraction gradient, as shown in Fig. 1 and Fig. 8. In other materials, such as fused quartz and polycarbonate plastic, the polarization in the direction of the stress is deflected foy the stress gradient and the polarization perpendicular to the stress experiences little or no deflection as shown in Fig.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)

Abstract

Aiguillage optique (10) comportant un matériau photoélastique et optiquement transparent (12) dont l'indice de réfraction peut être modifié par l'application d'une sollicitation mécanique, et qui assure la propagation d'un ou plusieurs faisceaux optiques à partir d'une fenêtre d'entrée (14) et vers une fenêtre de sortie (16) ménagée dans le matériau, ladite fenêtre d'entrée (14) étant apte à recevoir un faisceau optique provenant d'une source optique, et la fenêtre de sortie (16) étant apte à faire passer un faisceau optique du matériau photoélastique (12) à un récepteur de sortie optique; ainsi qu'un dispositif d'application d'un gradient de sollicitation audit matériau photoélastique (12) afin de modifier l'indice de réfraction et, de ce fait, le trajet optique du faisceau optique, lequel peut ainsi quitter un trajet normal dépourvu de sollicitations et suivre un trajet dévié et soumis à une sollicitation. On a prévu des systèmes optiques dans lesquels l'aiguillage optique sert à recevoir un faisceau optique provenant d'une source et à le diriger ou non vers un récepteur optique après l'avoir fait passer à travers le matériau optique photoélastique (12). On a également prévu un procédé de commutation optique d'un faisceau optique entre des positions normales et soumises à une sollicitation par l'application d'une sollicitation mécanique prédéterminée à un matériau photoélastique et optiquement transparent (12) de manière à former un gradient de sollicitation mécanique au sein du matériau photoélastique et optiquement transparent (12) et à assurer dans celui-ci un gradient d'indice de réfraction apte à provoquer la commutation du faisceau optique.
PCT/US1991/002773 1991-04-23 1991-04-23 Aiguillage optique photoelastique, systemes optiques l'utilisant, et procede d'utilisation WO1992018886A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1991/002773 WO1992018886A1 (fr) 1991-04-23 1991-04-23 Aiguillage optique photoelastique, systemes optiques l'utilisant, et procede d'utilisation

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Application Number Priority Date Filing Date Title
PCT/US1991/002773 WO1992018886A1 (fr) 1991-04-23 1991-04-23 Aiguillage optique photoelastique, systemes optiques l'utilisant, et procede d'utilisation

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WO1992018886A1 true WO1992018886A1 (fr) 1992-10-29

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999053634A1 (fr) * 1998-04-10 1999-10-21 Phoenix Controls Corporation Systeme de distribution photonique en reseau pour la detection des conditions ambiantes

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4830461A (en) * 1987-01-29 1989-05-16 Bridgestone Corporation Pressure-sensitive sensors
US4909594A (en) * 1989-02-23 1990-03-20 The Dow Chemical Company Optical coupler pressure or load sensor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4830461A (en) * 1987-01-29 1989-05-16 Bridgestone Corporation Pressure-sensitive sensors
US4909594A (en) * 1989-02-23 1990-03-20 The Dow Chemical Company Optical coupler pressure or load sensor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999053634A1 (fr) * 1998-04-10 1999-10-21 Phoenix Controls Corporation Systeme de distribution photonique en reseau pour la detection des conditions ambiantes
US6252689B1 (en) 1998-04-10 2001-06-26 Aircuity, Inc. Networked photonic signal distribution system

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