GB2068112A - Vibration detector - Google Patents
Vibration detector Download PDFInfo
- Publication number
- GB2068112A GB2068112A GB8002431A GB8002431A GB2068112A GB 2068112 A GB2068112 A GB 2068112A GB 8002431 A GB8002431 A GB 8002431A GB 8002431 A GB8002431 A GB 8002431A GB 2068112 A GB2068112 A GB 2068112A
- Authority
- GB
- United Kingdom
- Prior art keywords
- mounting
- optical fibres
- detector
- light receiving
- receiving surface
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
- G01H9/006—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors the vibrations causing a variation in the relative position of the end of a fibre and another element
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Measurement Of Radiation (AREA)
Abstract
A vibration detector includes a plurality of optical fibres 10 each having one end 11 illuminated and fixed in a mounting 12 to which mechanical vibrations are to be applied. The free ends 16 of the optical fibres correspondingly vibrate adjacent to a stationary light receiving surface 18, and are less restrained than the mounting. The detector also includes means to detect, and means 22 to indicate and/or to record detectable, fluctuations in the intensity of light incident upon the surface. The changes are caused by the number of free optical fibre ends directly opposite to the surface varying in response to vibrations thereof. The means to detect may comprise a photodetector, and may be coupled to a differentiating circuit arrangement A2, R2, C1. <IMAGE>
Description
SPECIFICATION
Vibration detectors
This invention relates to vibration detectors
It is an object of the present invention to provide a simple and compact vibration detector.
According to the present invention a vibration detector comprises a plurality of optical fibres, with one end of each optical fibre fixed within the vibration detector by a mounting for the optical fibres, a light source to illuminate the fixed ends of the plurality of optical fibres, the other end of each optical fibre is spaced by a finite distance from mounting, and is adjacent to, and is free to move relative to, a light receiving surface of means of the vibration detector to receive light transmitted by the plurality of optical fibres, at least the mounting is free to move with applied mechanical vibrations, and the mounting and the light receiving surface are relatively more rigidly restrained within the vibration detector compared with the restraints on the free ends of the optical fibres, the light receiving surface extends, at least generally, in a plane, and the means to receive light also includes a device to indicate and/or to record fluctuations in the intensity of light incident upon the light receiving surface, the arrangement being such that the free end of each optical fibre is capable of displacement to traverse passed the periphery of the light receiving surface, and detectable fluctuations in the intensity of light incident upon the light receiving surface are caused by displacement of at least some of the free ends of the plurality of optical fibres to traverse passed the periphery of the light receiving surface, in response to mechanical vibrations applied to the mounting, the amplitude of each displacement of the free ends of the optical fibres relative to the light receiving surface being greater than the amplitude of the corresponding movement of the mounting relative to the light receiving surface.
The mechanical vibrations may be applied to more than the mounting of the vibration detector, and it is not essential that the mounting moves relative to the light receiving surface in response to mechanical vibrations applied to the vibration detector, the mechanical vibrations being applied to both the mounting and to the light receiving surface. Alternatively, the mechanical vibrations may be applied to only the mounting, and/or the light receiving surface is mounted resiliently so as not to be subjected to mechanical vibrations applied to the vibration detector. With any arrangement it is convenient to consider the light receiving surface as being stationary within the vibration detector, when mechanical vibrations are applied to the detector.Then it is required that the parts of each optical fibre remote from the mounting are more flexible, within the vibration detector, than the flexibility associated with the mounting. The greater the flexibility associated with the parts of the optical fibres remote from the mounting, relative to the flexibility associated with the mounting, within the vibration detector, the greater the sensitivity of the vibration detector in detecting vibrations of the mounting.
For convenience, in this specification and the accompanying claims, an applied mechanical vibration, and a corresponding vibration of the mounting, are considered as causing a detectable fluctuation in the intensity of light incident upon the light receiving surface, and any movement of the mounting not causing a detectable fluctuation in the intensity of light incident upon the light receiving surface is not considered to be a vibration of the mounting.
Further, for convenience in this specification and the accompanying claims, reference is made only to light to be transmitted by the plurality of optical fibres, and it is to be considered that each such reference includes a reference to radiation in any convenient part of the spectrum, for example, ultraviolet radiation, or infra-red radiation, instead of visible light, being so transmitted. It is required that the vibration detector includes a source and a detector of the radiation so transmitted.
The present invention will now be described by way of example with reference to the accompanying drawing, which is a side elevation of the optical part of a vibration detector comprising one embodiment in accordance with the present invention, together with circuit arrangements connected to the output of a photodetector arranged to receive light from the optical part of the vibration detector, the circuit arrangements also being included in the vibration detector.
The illustrated vibration detector has a plurality of optical fibres 10, with one end 11 of each optical fibre 10 fixed within the vibration detector by a mounting 12 for the optical fibres 10. The mounting within the vibration detector in any convenient way. The fixed ends 11 of the optical fibres just protrude from the mounting 12, and are adjacent to a light source 14, comprising a light-emitting diode, the fixed optical fibre ends 11 being uniformly illuminated. The other end 16 of each optical fibre, spaced by a finite distance from the mounting, is adjacent to, and is free to move relative to, the radiation sensitive surface 18 of a photodetector (not otherwise shown).
The arrangement is such that the free end 16 of each optical fibre is capable of displacement to traverse passed the periphery of the radiation sensitive surface 18 of the photodetector. Hence, the vibration detector has an optical part including the plurality of optical fibres, and an electrical part including the photodetector. For convenience, the radiation sensitive surface 18 is considered to extend, at least generally, in a plane.
In response to mechanical vibrations applied to the mounting at least some of the free ends of the plurality of optical fibres are displaced to traverse passed the periphery of the radiation sensitive surface, to cause detectable fluctuations in the intensity of light incident upon the radiation sensitive surface, by the number of free ends of the optical fibres directly opposite to the radiation sensitive surface varying.
The mounting 12 and the radiation sensitive surface 18 are secured within the vibration detector so that the free ends 16 of the optical fibres are less restrained than both the mounting, and the radiation sensitive surface, to mechanical vibrations applied to the vibration detector. The mechanical vibrations may be applied to more than the mounting of the vibration detector, and it is not essential that the mounting moves relative to the radiation sensitive surface in response to mechanical vibrations applied to the vibration detector, the mechanical vibrations being applied to both the mounting and to the radiation sensitive surface. Alternatively, the mechanical vibrations may be applied to only the mounting, and/or the radiation sensitive surface is mounted flexibly so as not to be subjected to mechanical vibrations applied to the vibration detector.With any arrangement it is convenient to consider the light receiving surface as being stationary within the vibration detector when the detector is subjected to applied mechanical vibrations. Then it is required that the parts of each optical fibre remote from the mounting are more flexible, within the sensor, than the flexibility associated with the mounting.
Usually, an optical fibre has a composite structure, having an inner core through which light is to be transmitted, and a reflective outer sheath. For convenience, hereinafter in this specification and the accompanying claims, where convenient, when considering light transmitted through the detector, the lighttransmissive inner core of each optical fibre included in the vibration detector is considered to comprise the optical fibre.
Each of the plurality of optical fibres usually, as shown, has the same finite length between the mounting and the free end of each optical fibre, and the free ends of the plurality of optical fibres are distributed in a plane. The plurality of optical fibres have an axis of symmetry associated therewith through the centre of the mounting. Further, the free ends of the plurality of optical fibres are in a plane which is normal to the axis of symmetry associated with the optical fibres. It is convenient, as shown, but not essential, for this plane, in which at least substantially the free ends of the plurality of optical fibres are capable of being displaced, to be at least substantially parallel to the plane in which, at least generally, the radiation sensitive surface extends.
In addition, for convenience, it is considered that the vibration detector is responsive to mechanical vibrations applied to the mounting, and the mounting is free to vibrate, in a plane at least substantially parallel both to the plane in which, at least generally, the radiation sensitive surface extends, and to the plane in which the free ends of the plurality of optical fibres are distributed.
Avibration of the mounting causes a corresponding vibration of the free ends of the optical fibres.
Because the free ends of the optical fibres are less restrained within the vibration detector than both the radiation sensitive surface and the mounting, to vibrations applied to the detector, the amplitude of each vibration of the free ends of the optical fibres relative to the radiation sensitive surface is greater than the amplitude of the corresponding vibration of the mounting. The greater the flexibility associated with the parts of the optical fibres remote from the mounting, relative to the flexibility associated with the mounting within the vibration detector, the greater the sensitivity of the vibration detector in detecting vibrations of the mounting.
The mounting is moved from a rest position within the vibration detector in response to applied mechanical vibrations, and the mounting returns to this rest position when no longer subjected to mechanical vibrations. Corresponding displacements of the free end of each constituent optical fibre also are from a rest position, and the free end of the optical fibre returns to this rest position when no longer vibrating.
Each free end of an optical fibre is small in area compared with the area of the radiation sensitive surface, and at least some of the free ends are caused to traverse passed the periphery of the radiation sensitive surface in response to a mechanical vibration applied to the mounting.
Usually an applied mechanical vibration causes a sequence of a plurality of detectable fluctuations in the intensity of light received by the detector. The free ends of the optical fibres may vibrate with a different frequency from the frequency of vibrations applied to the mounting, and/or may have a longer duration than corresponding mounting vibrations.
In the absence of any mechanical vibration applied to the mounting, with the free ends of the plurality of optical fibres at their rest positions, the free ends of the plurality of optical fibres are symmetrically arranged in relation to the centre of the radiation sensitive surface, although only some of the free ends are directly opposite to the radiation sensitive surface. In response to the mechanical vibrations applied to the mounting the free ends of the plurality of optical fibres may become assymmetrically arranged in relation to the centre of the radiation sensitive surface, but this is not essential.
Usually, the mounting has a reciprocating movement along an axis, in the plane at least substantially parallel to the plane in which, at least generally, the radiation sensitive surface extends, and to the plane in which the free ends of the plurality of optical fibres are distributed. The free ends of the plurality of optical fibres are displaced correspondingly, along parallel axes. Possibly the mounting, together with the free ends of the plurality of optical fibres move along different axes, in their respective planes, at different times.
The criteria to cause a detectable fluctuation in the intensity of light incident upon the radiation sensitive surface may comprise a movement of the mounting of an amplitude greater than a threshold value, and/or a mounting movement having a maximum velocity associated therewith greater than a threshold value, and/or a mounting movement having a minimum duration associated therewith greaterthan a threshold value, these criteria being determined by the construction of the vibration detector.
The photodetector may have any convenient form, and may be a photodiode, arranged such that the magnitude of a parameter, such as current, of each output signal from the photodetector, is representative of the instantaneous intensity of light incident upon the radiation sensitive surface.
Circuit arrangements, also comprising parts of the vibration detector, are coupled to the output of the photodetector. In the illustrated arrangement the output of the detector is connected to an amplifier
Al with a resistive feedback connection R1. The waveform of an output signal of the amplifier Al, caused by a typical fluctuation of the intensity of light incident upon the radiation sensitive surface of the photodetector, is indicated at (a).The output of the amplifier Al is connected to a differentiating circuit arrangement, the differentiating circuit arrangement comprising an operational amplifier
A2, with a resistive feedback connection R2, and the amplifier A2 is coupled to the output of the amplifier
Al via a capacitor C1.The differentiating circuit arrangement differentiates with respect to time the magnitudes of the currents of the input signals received from the amplifier Al. The rates of variation of the voltages of the output signals from the differentiating circuit arrangement are greater than the corresponding rates of variation of the current magnitudes supplied to the differentiating circuit arrangement. Consequently, the vibration detector is more sensitive in operation than otherwise would be the case.The waveform of the output signal from the differentiating circuit arrangement, corresponding to the input signal waveform indicated at (a), is shown at (b). The output of the differentiating circuit arrangement is connected to a known device 20 to convert each output signal from the differentiating circuit arrangement into a signal having a corresponding square waveform, as indicated at (c). The output of this device 20 is connected to a device 22, to be driven by output signals from the device 20, and to indicate and/or to record detected fluctuations in the intensity of light incident upon the radiation sensitive surface. The device 22 may have any convenient form. Thus, the electrical circuit arrangements at least partially determine the criteria to cause a detectable fluctuation in the intensity of light incident upon the radiation sensitive surface.
If the mounting is subjected to a sudden discrete impulse in one direction, and the mounting subsequently returns to its rest position, and if, for example, the free ends of the plurality of optical fibres correspondingly each have an initial maximum speed, greater than a threshold value, associated therewith, and in only one direction relative to the centre of the radiation sensitive surface, and each free optical fibre end returns more slowly to its rest position, there may be caused only one detectable fluctuation in the intensity of light incident upon the radiation sensitive surface. Such a movement of the mounting, and corresponding displacement of the free ends of the plurality of optical fibres, each is considered to be a vibration detectable by the vibration detector.Hence, each constituent optical fibre may have a finite stiffness associated therewith, whilst still being capable of being considered as being flexible in character.
Usually the portions of the plurality of optical fibre between their free ends and the mounting are increasingly divergent the greater the distance from the mounting, especially if each optical fibre is not sufficiently stiff so that, in response to a sudden discrete impulse applied to the mounting, the free ends of the plurality of optical fibres are displaced to cause only one detectable fluctuation in the intensity of light incident upon the radiation sensitive surface.
The mounting may move, and the free ends of the plurality of optical fibres correspondingly may be displaced, with a circular or elliptical motion, possibly of a complex form, such movements of the mounting, and corresponding displacements of the free ends of the plurality of optical fibres, being capable of being considered as vibrations if they cause detectable fluctuations in the intensity of light incident upon the radiation sensitive surface.
Mechanical vibrations may be applied to the detector in any convenient way.
In response to the vibrations applied to the mounting, displacement of some of the free ends of the plurality of optical fibres, to traverse passed the periphery of the radiation sensitive surface, may be towards the radiation sensitive surface, whilst simultaneous displacement of other of the free ends is away from the radiation sensitive surface. However, it is required that the arrangement is such that the application of any mechanical vibration to the mounting causes detectable fluctuations in the intensity of light incident upon the radiation sensitive surface, by the number of free ends of the optical fibres directly opposite to the radiation sensitive surface varying.
The arrangement may be such that, in the absence of any mechanical vibration applied to the mounting, and with the free ends of the plurality of optical fibres at their rest positions, instead of the illustrated arrangement of only a portion of the light transmitted by the plurality of optical fibres being incident upon the radiation sensitive surface, either all, or none, of this light is incident upon the radiation sensitive surface, respectively, all, or none, of the free ends of the plurality of optical fibres at their rest positions being directly opposite to the radiation sensitive surface.
For any arrangement of the vibration detector in response to appropriate mechanical vibrations applied to the mounting, the initial direction of displacement of at least most of the free ends of the plurality of optical fibres may be either towards, or away from, the centre of the radiation sensitive surface.
In contrast to the illuminated arrangement, and in the absence of any mechanical vibration applied to the mounting, and with the free ends of the plurality of optical fibres at their rest positions, the free ends of the plurality of optical fibres may be arranged assymmetrical ly in relation to the centre of the radiation sensitive surface.
The vibration detector may be arranged to be responsive to movements of the mounting along only one linear axis, within the plane at least substantially parallel to the plane in which, at least generally, the radiation sensitive surface extends, possibly the mounting, and/or the free ends of the plurality of optical fibres, being restrained to be displaced only along, respectively, said linear axis, and at least one linear axis parallel thereto. Within one such an arrangement for the vibration detector, the free ends of the plurality of optical fibres are distributed only along one linear axis, parallel to the linear axis along which the mounting moves.
The arrangement may be such that light is to be incident upon a light receiving surface, and is to be transmitted to a device to indicate and/or to record fluctuations in the incident light. The device may comprise an optical display device, and the photodetector is omitted, the vibration detector not including a detector other than the display device. However, it is required that visible light is transmitted by the plurality of optical fibres. Thus, the vibration detector is wholly optical of form. The light receiving surface may have any convenient form, and, for example, may be provided by the end of at least one further optical fibre.
The light receiving surface, whether comprising the radiation sensitive surface of a photodetector, or not, may have any convenient shape, and may have a regular shape, for example, being circular. It is not essential that the centre of the light receiving surface is on the surface, for example, the surface having an annular shape, or having more than one discrete, and for example, part-annular, shaped, portion. The surface may, or may not, extend wholly within a plane.
The sensitivity of the vibration detectro may be increased by each optical fibre having associated therewith a weight per unit length adjacent to the free end of the optical fibre greater than the associated weight per unit length adjacent to the mounting. Small weights, considered to be parts of the optical fibres, may be affixed adjacent to the free ends of the optical fibres.
The vibration detector may have a non-linear response in relation to movements of the mounting, by, for example, the fixed ends of the plurality of optical fibres not being uniformly illuminated; and/ or the plurality of optical fibres being uniformly stiff; and/or the free ends of the optical fibres not being uniformly distributed when displaced from their rest positions within the vibration detector, and possibly also when at their rest positions; and/or the free ends of the optical fibres not being uniformly distributed about the centre of the light receiving surface when at their rest positions, particularly when the light receiving surface has a regular shape, for example, being circular or annular in shape.
Claims (10)
1. A vibration detector comprising a plurality of optical fibres, with one end of each optical fibre fixed within the vibration detector by a mounting for the optical fibres, a light source to illuminate the fixed ends of the plurality of optical fibres, the other end of each optical fibre is spaced by a finite distance from the mounting, and is adjacentto, and is free to move relative to, a light receiving surface of means of the vibration detector to receive light transmitted by the plurality of optical fibres, at least the mounting is free to move with applied mechanical vibrations, and the mounting and the light receiving surface are relatively more rigidly restrained within the vibration detector compared with the restraints on the free ends of the optical fibres, the light receiving surface extends, at least generally, in a plane, and the means to receive light also includes a device to indicate and/or to record fluctuations in the intensity of light upon the light receiving surface, the arrangement being such that the free ends of the optical fibre is capable of displacement to traverse passed the periphery of the light receiving surface, and detectable fluctuations in the intensity of light incident upon the light receiving surface are caused by displacement of at least some of the free ends of the plurality of optical fibres to traverse passed the periphery of the light receiving surface, in response to mechanical vibrations applied to the mounting, the amplitude of each displacement of the free ends of the optical fibres relative to the light receiving surface being greater than the amplitude of the corresponding movement of the mounting relative to the light receiving surface.
2. A detector as claimed in claim 1 arranged such that light to be incident upon the light receiving surface is to be transmitted to a device to indicate and/orto record fluctuations in the incident light.
3. A detector as claimed in claim 2 in which the device comprises an optical display device.
4. A detector as claimed in claim 2 or claim 3 in which the light receiving surface is provided by the end of at least one further optical fibre.
5. A detector as claimed in claim 1 in which the meansto receive lighttransmitted by the plurality of optical fibres includes a photodetector, the light receiving surface comprising the radiation sensitive surface of the photodetector, the magnitude of a parameter of each output signal from the photodetector being representative of the instantaneous intensity of light incident upon the radiation sensitive surface.
6. A detector as claimed in claim 5 in which the photodetector comprises a photodiode, and the current output of the photodiode is representative of the instantaneous intensity of light incident upon the radiation sensitive surface.
7. A detector as claimed in claim 5 or claim 6 in which a differentiating circuit arrangement is coupled to the output of the photodetector, to differentiate with respect to time the magnitudes of a parameter of input signals corresponding to output signals from the photodetector, each such magnitude being representative of the instantaneous intensity of light incident upon the radiation surface of the photodetector, the rate of variation of the magnitudes of a parameter of the output signals from the differentiating circuit arrangement being greater than the corresponding rate of variation of the magnitudes of the parameter of the input signals supplied to the differentiating circuit arrangement.
8. A detector as claimed in any one of the preceding claims in which each optical fibres has associated therewith a weight per unit length adjacent to the free end of the optical fibre greater than the associated weight per unit length adjacent to the mounting.
9. A detector as claimed in claim 8 in which small weights, considered to be parts of the optical fibres, are affixed adjacent to the free ends of the optical fibres.
10. A vibration detector substantially as described herein with reference to the accompanying drawing.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8002431A GB2068112B (en) | 1980-01-24 | 1980-01-24 | Vibration detector |
| DE19813100669 DE3100669A1 (en) | 1980-01-24 | 1981-01-12 | VIBRATION DETECTOR |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8002431A GB2068112B (en) | 1980-01-24 | 1980-01-24 | Vibration detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2068112A true GB2068112A (en) | 1981-08-05 |
| GB2068112B GB2068112B (en) | 1983-06-02 |
Family
ID=10510864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8002431A Expired GB2068112B (en) | 1980-01-24 | 1980-01-24 | Vibration detector |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE3100669A1 (en) |
| GB (1) | GB2068112B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1990015974A1 (en) * | 1988-06-09 | 1990-12-27 | Loughborough Consultants Limited | Method and apparatus for monitoring the tension in an elongate flexible member |
| ES2124158A1 (en) * | 1995-11-28 | 1999-01-16 | Univ Cantabria | Fibre optic sensor system for the measurement of accelerations or single-axis displacements suitable for working in electromagnetically hostile environments |
| ES2136525A1 (en) * | 1996-11-11 | 1999-11-16 | Univ Cantabria | Optical-fibre sensor system for measuring and/or monitoring biaxial movements or accelerations |
| ES2138541A1 (en) * | 1997-10-09 | 2000-01-01 | Univ Cantabria | Multipoint and auto-compensated optical-fibre accelerometer |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3807004A1 (en) * | 1987-03-02 | 1988-09-15 | Olympus Optical Co | ULTRASONIC TREATMENT DEVICE |
| DE3939573A1 (en) * | 1989-11-30 | 1991-06-06 | Baldur Dr Ing Barczewski | Sensor for measuring forces and derivable physical parameters - has light source connected to clamped end of elastically deflectable light conducting body, with position detector at other end |
| DE4312692C2 (en) * | 1993-04-20 | 1998-07-02 | Richter Thomas | Measuring device for detecting vibrations, pulses, shocks, accelerations or seismic excitations and uses of this measuring device |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT23438B (en) * | 1904-08-30 | 1906-03-10 | Alexander Behm | Measuring and recording device for vibrations. |
| DE445470C (en) * | 1925-02-19 | 1927-06-10 | Viktor Blaess Dr Ing | Resonance vibration meter |
| DE1930111C3 (en) * | 1969-06-13 | 1975-02-20 | Vierling, Oskar, Prof. Dr.Phil.Habil., 8553 Ebermannstadt | Optical device for measuring the movement of parts moving in relation to one another |
| DE2034344A1 (en) * | 1970-07-10 | 1972-01-13 | Ulrich H | Device for measuring physical quantities by measuring the intensity of a bundle of light rays |
| US4152940A (en) * | 1976-10-15 | 1979-05-08 | Oki Electric Industry Co., Ltd. | Vibration detector |
| DE2828311A1 (en) * | 1978-06-28 | 1980-01-10 | Maschf Augsburg Nuernberg Ag | DEVICE FOR MONITORING THE OPERATING VALUES OF A BEARING |
-
1980
- 1980-01-24 GB GB8002431A patent/GB2068112B/en not_active Expired
-
1981
- 1981-01-12 DE DE19813100669 patent/DE3100669A1/en not_active Ceased
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1990015974A1 (en) * | 1988-06-09 | 1990-12-27 | Loughborough Consultants Limited | Method and apparatus for monitoring the tension in an elongate flexible member |
| ES2124158A1 (en) * | 1995-11-28 | 1999-01-16 | Univ Cantabria | Fibre optic sensor system for the measurement of accelerations or single-axis displacements suitable for working in electromagnetically hostile environments |
| ES2136525A1 (en) * | 1996-11-11 | 1999-11-16 | Univ Cantabria | Optical-fibre sensor system for measuring and/or monitoring biaxial movements or accelerations |
| ES2138541A1 (en) * | 1997-10-09 | 2000-01-01 | Univ Cantabria | Multipoint and auto-compensated optical-fibre accelerometer |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2068112B (en) | 1983-06-02 |
| DE3100669A1 (en) | 1982-01-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |