EP2144207A1 - Système anti-intrusion à fibre optique - Google Patents

Système anti-intrusion à fibre optique Download PDF

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Publication number
EP2144207A1
EP2144207A1 EP09008963A EP09008963A EP2144207A1 EP 2144207 A1 EP2144207 A1 EP 2144207A1 EP 09008963 A EP09008963 A EP 09008963A EP 09008963 A EP09008963 A EP 09008963A EP 2144207 A1 EP2144207 A1 EP 2144207A1
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EP
European Patent Office
Prior art keywords
luminous
optical fiber
intrusion system
optical
source
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.)
Withdrawn
Application number
EP09008963A
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German (de)
English (en)
Inventor
Paolo Tagliabue
Natale Claudio Pistoni
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GPS Standard SpA
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Publication of EP2144207A1 publication Critical patent/EP2144207A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
    • G08B13/181—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems
    • G08B13/183—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems by interruption of a radiation beam or barrier
    • G08B13/186—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems by interruption of a radiation beam or barrier using light guides, e.g. optical fibres
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/02—Mechanical actuation
    • G08B13/12—Mechanical actuation by the breaking or disturbance of stretched cords or wires
    • G08B13/122—Mechanical actuation by the breaking or disturbance of stretched cords or wires for a perimeter fence
    • G08B13/124—Mechanical actuation by the breaking or disturbance of stretched cords or wires for a perimeter fence with the breaking or disturbance being optically detected, e.g. optical fibers in the perimeter fence
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/18—Prevention or correction of operating errors

Definitions

  • the present invention relates to the field of anti-intrusion systems and, in particular, it refers to an optical fiber anti-intrusion system.
  • These anti-theft devices 1, as shown in Figure 1 are arranged on a perimeter 2 of a building 3 and are connected to a processing system 4 designed to typically activate an alarming signal when a sensor 5 is stimulated, for example by means of a pressure of a foot of an ill-intentioned person.
  • Anti-intrusion systems using optical fiber that are used as sensors 5 are known.
  • An optical fiber is typically composed of a vitreous or plastic material and comprises at least an inner layer called core (fiber core) and an outer covering layer (hereinafter called using its technical name, cladding); the core typically possesses an index of refraction higher than the cladding; in this way, an optical beam, emitted either in the visible spectrum or in the IR, is typically confined inside the core by means of successive total reflections.
  • core fiber core
  • cladding outer covering layer
  • optical fibers have been efficiently used also outside the field strictly related to data transmission (for example in optical fiber nets) as sensors designed to identify an intrusion inside the perimeter 2 of a building 3.
  • the document US42964513 describes an anti-intrusion system using optical fibers that uses the principle of the differential detection of the signal present in a core of an optical fiber with the one contained in the cladding of the fiber itself.
  • the two signals are amplitude-modulated.
  • the document US 4297684 describes an intrusion detection system wherein a multi-mode optical fiber is used as sensor with detection of the changes of the speckle figure caused by the handling of the fiber itself due to the pressure of the ill-intentioned person weight.
  • the optical fiber is positioned in the ground and the system possesses also a spatial filter substantially constituted by a pin-hole, that is to say a very small hole made on a screen opaque to the light, that permits to detect the variations together with a photodiode.
  • the document US 5712937 also describes the entry of a light beam deriving from a plurality of photoemitters inside a single optical fiber.
  • optical fiber anti-intrusion systems of known type are characterized in that they have the disadvantage of possessing an high output optical noise, that therefore does not permit to correctly detect small variations or movements of the fiber itself and can cause missed alarms.
  • the purpose of the present invention is to realize an optical fiber anti-intrusion system, that is free from the above described drawbacks.
  • an optical fiber anti-intrusion system is realized as claimed in claim 1.
  • optical fiber anti-intrusion system is designated as a whole with the numeral 10.
  • the anti-intrusion system 10 comprises a luminous source 11 connected to a multi-mode optical fiber 12 having a core 12.1 and a cladding 12.2 that acts as sensor.
  • the luminous source 11 is preferably a single-mode Distributed FeedBack laser (also known as DFB laser) that comprises at least a totally reflecting mirror 11.1, a semi-reflecting mirror 11.2 directed toward the optical fiber 12, a layer of active semiconductor 11.3 and an optical grating 11.4 that realizes the distributed feedback.
  • DFB laser Distributed FeedBack laser
  • lasers with emission spectrum substantially centered on the third absorption window of the optical fibers, having a central wavelength of 1550nm are used. In fact, it is properly in the third window that the fibers present a lower absorption and, consequently, lower losses of optical power along their length.
  • the coupling between the luminous source 11 and the multi-mode optical fiber 12 is preferably made through a single-mode optical fiber interposed between them.
  • the coherent photon beam emitted by the luminous source 11 propagates in direction of the optical fiber 12 and within it in many modes, that is to say following different optical paths each having its own propagation characteristics; the number of the optical paths and the respective propagation characteristics of each single optical path depend on the geometrical characteristics of the fiber itself, on the emission wavelength of the photon beam and:
  • the photon beam emitted by the luminous source 11 is of monochromatic type, as output of the optical fiber 12 it is visible an image 100 ( Figure 3 ) that is not homogeneous, but characterized by the presence of a group of brilliant and dark points (Speckle image).
  • the image 100 is the result of the constructive or destructive interference of the various optical modes that propagate within the optical fiber 12.
  • the deformation of the fiber 12, for example a squashing or a flexion, causes a variation of the disposal of the brilliant points and of the dark points of the image 100 and this variation is used for permitting the detection of an intrusion inside a perimeter of a building.
  • the optical fiber 12 is suitable for being positioned in the ground, appropriately covered by one or more cladding layers 13 designed to prevent the contamination from external agents such as humidity, or on loose links, electrically welded and in stone enclosures.
  • a terminal part 12.3 of the optical fiber 12 is coupled to a spatial filter 14 that permits the passage of a restricted part of the luminous beam produced by the output of the optical fiber 12.
  • a variation sensibly higher is reached in a second image 101 detected behind the spatial filter 14 for example through a photodiode 15.
  • the photodiode 15 substantially measures the integral of the optical energy present on the image 101 and, when the optical fiber 12 is disturbed, it measures a luminous variation that is transformed into an alarm signal by a visual and/or acoustic device.
  • This variation can present a threshold level both temporal and in terms of the measured variation, under which the alarm signal is not activated.
  • the image 101 and a corresponding image 101' obtained in a condition of perturbation have an extremely different dark and light areas ratio.
  • the spatial filter 14 can comprise either a pin-hole filter or a section of single-mode optical fiber.
  • a single-mode optical fiber of standard size as spatial filter 14, coupled to the optical fiber 12, we would obtain a size of the hole equal to the core of the single-mode fiber that is tipycally of 9 ⁇ m whereas the diameter of the core 12.1 of the optical fiber 12 (multi-mode) is of 50ö62, 5 ⁇ m.
  • the piloting current of the luminous source 11 is of constant or non-constant type, for reducing the noise associated to the speckle figure; in this case, an amplitude modulation with frequencies of 20-50 KhZ, for example sinusoidal, is superimposed at a constant mean value; this modulation permits to use also a second type of luminous source consisting of a Fabry-Perot laser, characterized by reduced performances in terms of spectral purity of the emitted photon beam for the presence of many longitudinal modes. This lack of purity is counterbalanced by the modulation of the piloting current.
  • optical fiber anti-intrusion system described up to this point permits to ensure an effective detection of the passage of ill-intentioned people within the perimeter of a building and a high rejection toward tipycal interferences of the systems of this type also thanks to a modulation of the current injected into the optical source.
  • optical isolators designed to drastically reduce the retroreflections directed toward the cavity of the optical source itself that are sources of further noises on the detected signal and therefore of uncertainty in the determination of the intrusion can be interposed.
  • optical fibers 12 can be coupled in substantially parallel direction one with respect to the other in such a way as to ensure first of all a systemic redundancy (that is to say protection in case of fiber failures for example after the breaking of the photodetector) and for a higher safety of trampling or breaking in case of application on enclosures. In this case, the alarm would go off alternatively or in combination, if the first or second optical fiber are stimulated.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Prostheses (AREA)
  • Window Of Vehicle (AREA)
  • Optical Communication System (AREA)
  • Burglar Alarm Systems (AREA)
EP09008963A 2008-07-11 2009-07-09 Système anti-intrusion à fibre optique Withdrawn EP2144207A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ITTO2008A000535A IT1391026B1 (it) 2008-07-11 2008-07-11 Sistema di antintrusione in fibra ottica

Publications (1)

Publication Number Publication Date
EP2144207A1 true EP2144207A1 (fr) 2010-01-13

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ID=41168572

Family Applications (1)

Application Number Title Priority Date Filing Date
EP09008963A Withdrawn EP2144207A1 (fr) 2008-07-11 2009-07-09 Système anti-intrusion à fibre optique

Country Status (2)

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EP (1) EP2144207A1 (fr)
IT (1) IT1391026B1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103123739A (zh) * 2012-12-05 2013-05-29 北京航天易联科技发展有限公司 光纤周界入侵报警系统信号处理单元测试装置
CN105261134A (zh) * 2015-10-28 2016-01-20 贾波 基于光纤传感的城市管网防侵入报警系统
CN103995969B (zh) * 2014-05-23 2017-02-15 天津大学 一种可配置的光纤侵犯事件发生端点检测方法以及检测仪
WO2020183395A1 (fr) * 2019-03-12 2020-09-17 Hutek Inc Sas Système et procédé pour la détection de vibrations à la périphérie d'une fibre optique

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4297684A (en) 1979-03-26 1981-10-27 Honeywell Inc. Fiber optic intruder alarm system
GB2098770A (en) * 1981-05-13 1982-11-24 Factor Enterprises Ltd X Security barrier structure
WO1984004985A1 (fr) * 1983-06-03 1984-12-20 Hughes Technology Pty Ltd Systeme de securite a laser
DE3322044A1 (de) * 1983-06-18 1984-12-20 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Einrichtung zur ueberwachung und bekaempfung
DE3322046A1 (de) * 1983-06-18 1984-12-20 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Lichtleiter-druck- und eindringsensor
US5194847A (en) * 1991-07-29 1993-03-16 Texas A & M University System Apparatus and method for fiber optic intrusion sensing
US5712937A (en) 1994-12-01 1998-01-27 Asawa; Charles K. Optical waveguide including singlemode waveguide channels coupled to a multimode fiber
WO2001039148A1 (fr) * 1999-11-24 2001-05-31 Future Fibre Technologies Pty Ltd Procede et systemes de surveillance d'une barriere de protection perimetrique
US7092586B2 (en) 2003-07-18 2006-08-15 Network Integrity Systems Inc. Intrusion detection system for use on an optical fiber using a translator of transmitted data for optimum monitoring conditions
US20070069893A1 (en) * 2005-03-04 2007-03-29 Compudyne Corporation Polarization-based sensor for secure fiber optic network and other security applications

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4297684A (en) 1979-03-26 1981-10-27 Honeywell Inc. Fiber optic intruder alarm system
GB2098770A (en) * 1981-05-13 1982-11-24 Factor Enterprises Ltd X Security barrier structure
WO1984004985A1 (fr) * 1983-06-03 1984-12-20 Hughes Technology Pty Ltd Systeme de securite a laser
DE3322044A1 (de) * 1983-06-18 1984-12-20 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Einrichtung zur ueberwachung und bekaempfung
DE3322046A1 (de) * 1983-06-18 1984-12-20 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Lichtleiter-druck- und eindringsensor
US5194847A (en) * 1991-07-29 1993-03-16 Texas A & M University System Apparatus and method for fiber optic intrusion sensing
US5712937A (en) 1994-12-01 1998-01-27 Asawa; Charles K. Optical waveguide including singlemode waveguide channels coupled to a multimode fiber
WO2001039148A1 (fr) * 1999-11-24 2001-05-31 Future Fibre Technologies Pty Ltd Procede et systemes de surveillance d'une barriere de protection perimetrique
US7092586B2 (en) 2003-07-18 2006-08-15 Network Integrity Systems Inc. Intrusion detection system for use on an optical fiber using a translator of transmitted data for optimum monitoring conditions
US20070069893A1 (en) * 2005-03-04 2007-03-29 Compudyne Corporation Polarization-based sensor for secure fiber optic network and other security applications

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103123739A (zh) * 2012-12-05 2013-05-29 北京航天易联科技发展有限公司 光纤周界入侵报警系统信号处理单元测试装置
CN103123739B (zh) * 2012-12-05 2016-01-20 北京航天易联科技发展有限公司 光纤周界入侵报警系统信号处理单元测试装置
CN103995969B (zh) * 2014-05-23 2017-02-15 天津大学 一种可配置的光纤侵犯事件发生端点检测方法以及检测仪
CN105261134A (zh) * 2015-10-28 2016-01-20 贾波 基于光纤传感的城市管网防侵入报警系统
CN105261134B (zh) * 2015-10-28 2018-05-08 贾波 基于光纤传感的城市管网防侵入报警系统
WO2020183395A1 (fr) * 2019-03-12 2020-09-17 Hutek Inc Sas Système et procédé pour la détection de vibrations à la périphérie d'une fibre optique

Also Published As

Publication number Publication date
IT1391026B1 (it) 2011-10-27
ITTO20080535A1 (it) 2010-01-12

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