WO1995023551A1 - Mesure de la pression par fibres optiques - Google Patents

Mesure de la pression par fibres optiques Download PDF

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Publication number
WO1995023551A1
WO1995023551A1 PCT/EP1995/000777 EP9500777W WO9523551A1 WO 1995023551 A1 WO1995023551 A1 WO 1995023551A1 EP 9500777 W EP9500777 W EP 9500777W WO 9523551 A1 WO9523551 A1 WO 9523551A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical waveguide
pressure
measuring device
pressure sensor
pressure measuring
Prior art date
Application number
PCT/EP1995/000777
Other languages
German (de)
English (en)
Inventor
Hans Petersen
Original Assignee
Diehl Gmbh & Co.
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 Diehl Gmbh & Co. filed Critical Diehl Gmbh & Co.
Publication of WO1995023551A1 publication Critical patent/WO1995023551A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
    • A61B5/7214—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/03—Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
    • G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
    • 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

Definitions

  • the invention relates to a pressure measuring device, in particular for medical pressure measurements, with a mechanical pressure sensor which is connected to evaluation electronics via an optical waveguide, a light signal being supplied to the optical waveguide and a measuring signal corresponding to the prevailing pressure to the evaluation electronics directs.
  • Such a pressure measuring device is described in DE 40 18 998 AI.
  • a membrane which is exposed to the pressure to be measured is arranged on the pressure sensor, the center of which is opposite the optical waveguide.
  • the light beam from the optical waveguide strikes the reflecting membrane and is guided in the optical waveguide in accordance with the pressure-dependent distance and guided in the optical waveguide to the evaluation electronics.
  • strain gauge bridges For medical pressure measurements, strain gauge bridges, piezo crystal sensors are used, for example, which are connected to the evaluation electronics via wire connections. Electrical connections between the respective sensor and the evaluation electronics are necessary. Such are often undesirable. The electrical lines could be avoided by wireless connections. However, an electrical energy supply would then have to be provided in the sensor. This would increase the size of the sensor which is particularly disadvantageous in medical pressure measurements in which the sensor is to be placed on or in the patient.
  • the optical waveguide In the case of pressure measurements, particularly in medical technology, the optical waveguide must be flexible so that it can be guided flexibly to the measuring point in question. It has been found that such movements of the optical waveguide lead to falsifications of the measurement result.
  • the object of the invention is to propose a pressure measuring device of the type mentioned at the outset, in which falsifications of the measurement result which arise when the optical waveguide is moved or bent are compensated for.
  • the above object is achieved in a pressure measuring device of the type mentioned at the outset in that a comparative optical waveguide is guided parallel to the optical waveguide, which can be moved together with it and which, like the optical waveguide, conducts a light signal, and in that the light signal for comparison -Light waveguide is unaffected by the pressure in the pressure sensor and is supplied as a reference signal to the evaluation electronics, which compensates for movement-related changes in the measured value by means of the reference signal.
  • the optical waveguide and the comparison optical waveguide are subject to the same movement-related disturbances.
  • the light signal is influenced by the measured variable only in the optical waveguide.
  • the light signals of the optical waveguide and the comparison optical waveguide can be processed in the manner of a measuring bridge, so that "in the end result the measured value is not falsified by movements or bends of the optical waveguide.
  • the pressure measuring device requires no galvanic connection between the pressure sensor and the evaluation electronics and no active transmitter in the pressure sensor. As a result, the pressure sensor can be constructed very small, so that it can also be easily introduced into parts of a patient's body.
  • FIG. 1 shows a schematic diagram of a pressure measuring device that works on the principle of an interferometer
  • FIG. 2 is a circuit diagram of another embodiment of the invention.
  • FIG. 3 shows a circuit diagram of a pressure measuring device which works with a damping measurement
  • FIG. 4 shows a sectional view of a pressure sensor along the line IV-IV according to FIG. 5, enlarged
  • FIG. 5 shows a top view of the pressure sensor according to FIG. 4,
  • Figure 6 shows a different type of pressure sensor in section
  • the pressure measuring device has an optical fiber arrangement (1) which contains a pressure sensor (2), an optical fiber (3) and a comparative optical fiber (4).
  • the mechanical structure of the pressure sensor (2) is shown in Figures 4 and 5.
  • the optical waveguide (3) and the comparative optical waveguide (4) each have a piece leading to the pressure sensor (2) and a piece leading away from the pressure sensor (2).
  • the four Pieces lead into the pressure sensor (2) on the same side (cf. Fig. 4.5).
  • the comparison optical fiber (4) and the optical fiber (3) are laid parallel to each other. They are flexibly movable and run in a common protective tube (5).
  • the pressure sensor (2) has a base body (6), which rather carries a pressure-sensitive membrane (7).
  • the membrane (7) When pressure is applied in the direction of arrow (D), the membrane (7) is deflected.
  • the back (8) of the membrane (7) is mirrored.
  • the optical fiber (3) ends with its two parallel pieces in the pressure sensor (2) in front of a mirrored deflecting surface (9), which directs the light emerging from one piece of the optical fiber (3) onto the mirrored rear side (8) of the membrane (7) Which leads light via the deflecting surface (9) back into the outgoing piece of the optical waveguide (3).
  • the outgoing light is influenced in relation to the incoming light.
  • the comparison optical fiber (4) is also guided into the pressure sensor (2). However, its two parallel pieces are connected there so that they are not influenced by the membrane (7).
  • the deflection surface (9) can, as shown in FIG. 5, be an integral part of the base body (6). Alternatively, it can also be a separate prism component which is inserted and fastened in the base body (6) at the specific position.
  • the deflecting surface (9) runs at an angle of 45 °.
  • the light guide arrangement (1) is connected to an evaluation electronics (10) by means of plugs (not shown).
  • the two optical fibers (3, 4) are supplied with a light signal by a laser diode (11) via a semi-transparent mirror (12).
  • an actuator (13) is arranged, which in its function is similar to the membrane (7) of the pressure sensor (2) and with which the optical length of the comparison optical waveguide (4 ) can be adjusted accordingly.
  • the actuator (13) is a motor-adjustable mirror or a magnetostrictively extendable optical waveguide.
  • the light signals from the optical waveguide (3) and the comparative optical waveguide (4) are fed to a light receiver (15) via a semitransparent mirror (14).
  • the received signal is amplified in an amplifier (16) and passed to a controller (17).
  • the controller (17) adjusts the actuator (13) so that the output voltage at the amplifier (16) becomes a minimum. This is the case if the optical length in the section of the optical waveguide (3) is equal to the optical length in the section of the comparison optical waveguide (4).
  • the adjustment of the actuator (13) required for this is displayed. It represents the pressure measured value.
  • the measured value does not contain any disturbances, for example bending-related disturbances which affect the two optical waveguides (3, 4) in the same way.
  • a corresponding change in length (d4) is set in accordance with the respective pressure-dependent optical change in length (d3) in the optical waveguide ⁇ ) in the comparison optical waveguide (4) and this is displayed.
  • the light signal fed to the optical fibers (3, 4) via laser diodes (11, 11 ') is UHF-modulated, the frequency (fl) being in the range from, for example, 100 MHz to 1 GHz and around 30 kHz in the modulator (18) from one Regle (19) is adjustable.
  • the comparison optical waveguide (4) is preceded by an optical path (20) of length lamda / 4 of fl.
  • Light receivers (15, 15 ') of the evaluation electronics (10) feed the light signals of the optical fibers (3, 4) to a phase detector (21) which controls the controller (19).
  • the controller (19) controls the frequency (fl) so that there is a phase shift of 90 °.
  • the deviation from this is proportional to the pressure-dependent deflection (d3). This can be shown on a display (22). In this case too, falsifications due to bending of the optical fibers (3, 4) are compensated for in the measurement result.
  • the evaluation electronics (10) work with a 20 kHz generator (23) which is connected to IR diodes (11, 11 ') via an actuator (24) and an LED driver (25), which are coupled to the light guides (3, 4).
  • Light receivers (15, 15 ') are connected to electrical amplifiers (26, 26'), to which the voltages correspond to the light attenuation in the optical waveguide (3) with the respective measuring path (d3) and the comparative light waveguide (4) (Ul or U2).
  • the voltages (U1, U2) are applied to a micro-controller (28) via phase rectifiers (27, 27 "" ) controlled by the generator (23) and, if appropriate, further amplifiers.
  • a controller (29) is connected to this, which controls the actuator (24) in such a way that the voltage (U2) derived from the comparison optical fiber (4) remains constant.
  • the optical fibers (3, 4) have wide tolerances that cannot be easily compensated for by the evaluation electronics (10).
  • a comparison of each light guide arrangement within a narrow tolerance range would be complex.
  • the light guide arrangements (1) are manufactured within a tolerance range which can easily be maintained in mass production.
  • the pressure characteristic curve of the respective light guide arrangement (1) is traversed in a measuring computer. From the comparison of the actual characteristic curve with a standard characteristic curve, the measuring computer calculates adaptation values for the slope and the zero point, which are embodied by ohmic resistances (X, Y). These resistors (X, Y) are inserted into the plugs of the light guide arrangement (1).
  • an intended pair of resistors (X, Y) can also be adjusted by means of laser adjustment, or a bar coding can be used.
  • the microcontroller (28) takes over the resistance values (X, Y) and generates control variables (x, y) with which voltage adjustment elements (30 , 31) (cf. FIG. 3) are preset accordingly.
  • a changeover switch (32) is provided, which is brought into its position for calibration and for its measurement in position (b).
  • Position (a) corresponds to an unpressurized sensor the zero position.
  • the pressure sensor (2) is drawn in a design modified from that in FIG.
  • a Teflon tube (34) is inserted in a bore (33) of the base body (6) and detaches from the face of an annular shoulder (35) of the bore (33).
  • An inner wedge (36) which is led out of the front of the Teflon tube (34) and, is located centrally in the teflon tube (34) with an inner diameter of approximately 1.0 millimeter ends in front of the membrane (7).
  • the first pair of the optical waveguide (3) is arranged, the end exits of which extend as far as the membrane (7).
  • the two pieces of the second, so-called reference light waveguide (4) are provided on the underside and end at a distance from a shoulder (37) of the inner wedge (36).
  • the pairs of optical fibers (3, 4) are firmly connected to the inner wedge, which can be done, for example, by shrinking in order to maintain their position precisely.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Surgery (AREA)
  • Medical Informatics (AREA)
  • General Physics & Mathematics (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Signal Processing (AREA)
  • Animal Behavior & Ethology (AREA)
  • Physiology (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Psychiatry (AREA)
  • Hematology (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

Dispositif de mesure de la pression, notamment pour la mesure de pressions en médecine, dans lequel un capteur de pression mécanique est relié par un guide d'ondes lumineuses (3) à un système électronique d'évaluation (10). Pour compenser un résultat de mesure faussé par des mouvements et des inflexions du guide d'ondes lumineuses (3), parallèlement audit guide (3) est installé un guide d'ondes lumineuses de référence (4) qui, comme le premier (3), peut être déplacé de manière flexible. Le signal lumineux du guide d'ondes lumineuses de référence (4) n'est pas influencé par la pression dans le capteur de pression (2) et est acheminé en tant que signal de référence vers le système électronique d'évaluation (10), lequel compense par ledit signal de référence les modifications de la valeur mesurée, provoquées par les mouvements.
PCT/EP1995/000777 1994-03-04 1995-03-03 Mesure de la pression par fibres optiques WO1995023551A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4407176.0 1994-03-04
DE19944407176 DE4407176A1 (de) 1994-03-04 1994-03-04 Druckmessung mittels Faseroptik

Publications (1)

Publication Number Publication Date
WO1995023551A1 true WO1995023551A1 (fr) 1995-09-08

Family

ID=6511829

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1995/000777 WO1995023551A1 (fr) 1994-03-04 1995-03-03 Mesure de la pression par fibres optiques

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DE (1) DE4407176A1 (fr)
WO (1) WO1995023551A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013210349A1 (de) * 2013-06-04 2014-12-04 Conti Temic Microelectronic Gmbh Optische Druckmessvorrichtung und optisches Druckmessverfahren

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4487206A (en) * 1982-10-13 1984-12-11 Honeywell Inc. Fiber optic pressure sensor with temperature compensation and reference
GB2186360A (en) * 1986-02-07 1987-08-12 Ford Motor Co Stress transducer
US4687927A (en) * 1984-12-13 1987-08-18 Kabushiki Kaisha Toshiba Pressure measuring system
EP0455241A2 (fr) * 1990-05-02 1991-11-06 Dynisco, Inc. Transducteur de pression optique
US5065010A (en) * 1990-08-30 1991-11-12 Camino Laboratories Fiber optic measurement system having a reference conductor for controlling the energy level of the light source
US5107847A (en) * 1983-05-25 1992-04-28 Camino Laboratories Fiber-optic transducer apparatus

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3327584A (en) * 1963-09-09 1967-06-27 Mechanical Tech Inc Fiber optic proximity probe
DE2518197A1 (de) * 1975-04-24 1976-11-04 Guenter Dipl Phys Dr Smeets Schnelle phasennachfuehrung fuer laser-interferometer
GB2147695B (en) * 1983-10-05 1987-03-18 Standard Telephones Cables Ltd Balancing interferometer sensor
GB2193310A (en) * 1986-08-01 1988-02-03 Boc Group Plc Pressure sensor
DE8802025U1 (fr) * 1988-02-17 1988-03-31 Fibronix Faseroptische Sensoren + Systeme Gmbh, 2300 Kiel, De
DE3816529A1 (de) * 1988-05-14 1989-11-23 Kistler Instr Gmbh Druckmessvorrichtung
DE4018998A1 (de) * 1990-06-13 1992-01-02 Dynisco Geraete Gmbh Faseroptischer drucksensor
DE4128687A1 (de) * 1991-08-29 1993-03-04 Asea Brown Boveri Faseroptischer sensor

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4487206A (en) * 1982-10-13 1984-12-11 Honeywell Inc. Fiber optic pressure sensor with temperature compensation and reference
US5107847A (en) * 1983-05-25 1992-04-28 Camino Laboratories Fiber-optic transducer apparatus
US4687927A (en) * 1984-12-13 1987-08-18 Kabushiki Kaisha Toshiba Pressure measuring system
GB2186360A (en) * 1986-02-07 1987-08-12 Ford Motor Co Stress transducer
EP0455241A2 (fr) * 1990-05-02 1991-11-06 Dynisco, Inc. Transducteur de pression optique
US5065010A (en) * 1990-08-30 1991-11-12 Camino Laboratories Fiber optic measurement system having a reference conductor for controlling the energy level of the light source

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Publication number Publication date
DE4407176A1 (de) 1995-09-07

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