WO2020032798A1 - Mechanical multiplexing of optical sensor - Google Patents

Mechanical multiplexing of optical sensor Download PDF

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Publication number
WO2020032798A1
WO2020032798A1 PCT/NL2019/050522 NL2019050522W WO2020032798A1 WO 2020032798 A1 WO2020032798 A1 WO 2020032798A1 NL 2019050522 W NL2019050522 W NL 2019050522W WO 2020032798 A1 WO2020032798 A1 WO 2020032798A1
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WO
WIPO (PCT)
Prior art keywords
optical sensor
fibre
sensor system
light
optical
Prior art date
Application number
PCT/NL2019/050522
Other languages
French (fr)
Inventor
Albert Van Duijn
Bernard Johan Oppedijk
Frederik Pius Van Horssen
Original Assignee
Fytagoras B.V.
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Filing date
Publication date
Application filed by Fytagoras B.V. filed Critical Fytagoras B.V.
Publication of WO2020032798A1 publication Critical patent/WO2020032798A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/7703—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator using reagent-clad optical fibres or optical waveguides
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/6408—Fluorescence; Phosphorescence with measurement of decay time, time resolved fluorescence
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
    • G01N2021/6434—Optrodes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/645—Specially adapted constructive features of fluorimeters
    • G01N2021/6484—Optical fibres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/7703—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator using reagent-clad optical fibres or optical waveguides
    • G01N2021/7706—Reagent provision
    • G01N2021/772—Tip coated light guide
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N2021/7769—Measurement method of reaction-produced change in sensor
    • G01N2021/7773—Reflection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N2021/7769—Measurement method of reaction-produced change in sensor
    • G01N2021/7786—Fluorescence
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
    • G01N2021/8528—Immerged light conductor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/08—Optical fibres; light guides
    • G01N2201/0853—Movable fibre optical member, e.g. for scanning or selecting
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/36—Mechanical coupling means
    • G02B6/3616—Holders, macro size fixtures for mechanically holding or positioning fibres, e.g. on an optical bench
    • G02B6/3624—Fibre head, e.g. fibre probe termination
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4439—Auxiliary devices
    • G02B6/4457—Bobbins; Reels

Definitions

  • the various aspects and implementations thereof relate to an optical sensor system.
  • Fluorescent and/or reflective coatings of which optical properties change due to changing parameters in the surroundings of the coating are known. Light reflected or emitted from such a coating may be received by an optical sensor, which may be used for determining information on the parameter in the surrounding of the coating.
  • a first aspect provides an optical sensor system, comprising an optical sensor module comprising an optical sensor and an optical sensor input, the optical sensor being arranged for generating a data signal in response to receiving light received by the optical sensor input, the data signal carrying information related to information carried by the received hght.
  • the optical sensor system further comprises a plurality of light communication ports for providing an emitted or reflected light signal, the hght communication ports being spaced apart along a first axis.
  • the optical sensor system also comprises a driving module, arranged to drive a first of the optical sensor input and the plurality light communication ports along the first axis relative to a second of the optical sensor input and the plurality of light communication ports such that the optical sensor may be aligned with at least a first light communication port and a second light communication port for receiving light from the light communication ports.
  • a driving module arranged to drive a first of the optical sensor input and the plurality light communication ports along the first axis relative to a second of the optical sensor input and the plurality of light communication ports such that the optical sensor may be aligned with at least a first light communication port and a second light communication port for receiving light from the light communication ports.
  • An optical sensor system capable of receiving an emitted or reflected light signal from a plurality of light communication ports with a single optical sensor input.
  • An aim of the optical sensor system is to determine at the location of the optical sensor system parameters at a plurality of remote locations or multiple parameters at one or more locations.
  • Remote locations are locations at which the optical sensor system would be unable to measure directly because for example they are too far away or there are obstacles present between the remote location and the optical sensor system which block light travelling directly in a straight line from the remote location to the optical sensor system.
  • optical sensor system With the ability of the optical sensor system to align a single optical sensor module with a plurality of light communication ports, a simpler and cheaper system may be provided compared to having a single optical sensor module per light communication port.
  • the optical sensor modules are often more expensive and complex than the light
  • optical sensor module it is therefore preferred to have one optical sensor module and a plurality of light communication ports.
  • optical sensor system comprising a plurality of optical sensor modules and a single light communication port may be envisioned as well.
  • the light communication ports may be two-way ports, that is they may be arranged to send light and receive light.
  • the optical sensor module further comprises a light source for providing light to the light communication ports.
  • the light source may optionally be a tunable light source having a narrow band emission spectrum that may be tuned.
  • light having a narrow band emission spectrum light is meant which comprises a single wavelength, or which acts substantially as if it consist only a single wavelength, for example because it has a very narrow bandwidth, of a few nanometres, for example a maximum bandwidth of 20 nanometres, preferably 10 nanometres and even more preferred 5 nanometres.
  • Such light has the advantage that noise from unwanted wavelengths can be prevented.
  • An embodiment of the optical sensor system comprises a processing unit arranged to control a wavelength of light emitted by the (tunable) light source.
  • the processing unit may further be arranged for receiving the data signal generated by the optical sensor in response to receiving hght from the light communication port with which the optical sensor is aligned.
  • tunable hght source a light source is implied of which the wavelength or ranges of wavelengths emitted can be controlled.
  • the optical sensor system comprises a first data storage module for storing expected sensor response data.
  • the processing unit is further arranged to control the driving module to ahgn the optical sensor with the first light communication port, control the light source to vary the wavelength over a pre-determined interval, receive the data signal from the optical sensor, retrieve at least part of the expected sensor response data, and determine, based on an outcome of a comparison between the received data signal and the retrieved data, an entity of which a magnitude is represented by the received signal.
  • An embodiment of the optical sensor system further comprises a second data storage module for storing address information.
  • the processing unit may be arranged to store and retrieve data in and from the second data storage module, which data comprises a record comprising a location of a light communication port and a wavelength or range of wavelengths.
  • the driving module is further arranged to drive the first of the optical sensor input and the plurality of light communication ports along a second axis relative to the second of the optical sensor input and the plurality of light communication ports.
  • the plurality of light communication ports are spaced apart along the first axis and the second axis. Spacing the plurality of light communication ports along the first axis and the second axis allows for a more compact optical sensor system.
  • the first axis is perpendicular to the second axis.
  • both axes are linear axes along which the first of the optical sensor input and the plurality of light communication ports may be translated by the driving module.
  • Embodiments of the optical sensor system may also be envisioned wherein the first axis is a rotating or curved axis. Such a rotating or curved axis allows for a more compact optical sensor system as the light
  • communication ports may be provided at different angles relative to the optical sensor input.
  • the optical sensor input is mounted on the driving module such that the driving module is arranged for driving the position of the optical sensor input relative to the plurality of light communication ports.
  • the optical sensor input is the first of the optical sensor input and the plurality of light communication ports.
  • the optical sensor input comprises an optical fibre which is at a proximal end connected to the optical sensor.
  • the optical fibre allows communication of light between the optical sensor and the optical sensor input.
  • the plurality of light communication ports are arranged for receiving an optical fibre.
  • Such an optical fibre allows communication of fight between the light communication port and a remote location.
  • Another embodiment of the optical sensor system comprises a fibre driving module for driving an optical probing fibre, in particular for inserting or with chawing a distal end of the optical probing fibre in or from a medium.
  • Such an embodiment of the optical sensor system comprising the fibre driving module may further comprise a fibre driving controller arranged to control operation of the fibre driving module and connected to the optical sensor, wherein the fibre driving controller is further arranged to withdraw or bring in the optical probe fibre if the data signal from the fibre or a nearby fibre satisfies a pre-determined criterion.
  • Fig. 1A shows an embodiment of an optical sensor system
  • Fig. IB shows another embodiment of the optical sensor system
  • Fig. 2A shows yet another embodiment of the optical sensor system
  • Fig. 2B shows the optical sensor system with a withdraw optical probing fibre
  • Fig. 3 shows another embodiment of an optical sensor system and a device for inserting fibres in and with chawing fibres from a medium.
  • Fig. 1A shows an embodiment of an optical sensor system 100, comprising an optical sensor module 102.
  • the optical sensor module 102 comprises an optical sensor 104 and an optical sensor input 106, wherein the optical sensor 104 is arranged for generating a data signal in response to hght received via the optical sensor input 106.
  • the data signal carries information related to information carried by the received light.
  • the received light may be communicated from the optical sensor input 106 to the optical sensor 104 through a flexible optical fibre 107.
  • the optical sensor input 106 is directly coupled to the optical sensor 104, for example by means of a rigid connection and optionally in a single housing.
  • Information carried by the received light may relate to properties of the light, such as a light intensity, a range of wavelengths comprised by the light, any other property or a combination thereof.
  • the range of wavelengths may comprise one of more distinct ranges of wavelengths, or may comprise one or more single wavelengths.
  • electromagnetic radiation is meant and light is not restricted to light visible by the human eye (380 nm to 800 nm) and may extend from far infrared (1 millimetre) to far ultraviolet (10 nm).
  • a more narrow range may be covered, from approximately 100 nm to 1 mih or from 200 nm to 2 pm.
  • the optical sensor system 100 may further comprise a housing
  • a plurality of light communication ports comprising a first light
  • the communication port 108 and a second light communication port 110 may be provided in one or more sides of the housing.
  • the plurality of hght communication ports is provided such that light may be communicated from and/or to the plurality of light communication ports from outside and inside the housing 101.
  • the housing 101 may be arranged such that light from outside the housing is prevented from reaching the optical sensor input 106, preventing noise in the data signal generated by the optical sensor 104.
  • the optical sensor system 100 as shown in Fig. 1A comprises the first light communication port 108 and the second light communication port 110 spaced apart along a first axis 150.
  • the optical sensor system 100 may comprise more ports.
  • the light communication ports are arranged for passing through an emitted or reflected light signal.
  • a light communication port is arranged for receiving a ⁇ proximal end of a fibre, which fibre comprises a fluorescent or reflective coating at a distal end.
  • the light optical properties of the fluorescent or reflective coating change according to ambient parameters of the coating. Such reflecting properties may relate to a fluorescence wavelength, life-time or yield or the reflection coefficient or absorption coefficient changing under the influence of a varying entity at the distal end. Light reflected may have the same wavelength as received by the distal end or one or more different wavelengths.
  • the fibre received by a communication port is at the distal end connected to a proximal end of a further fibre which carries the fluorescent or reflective coating at its distal end.
  • Ambient parameters represent particular entities, for example be a temperature, pressure, pH level, oxygen level, levels of other substances and gases in particular, any other parameter or any combination thereof.
  • the ambient environment is preferably a fluid containing environment and more in particular a liquid containing environment like water. In the latter case, the level of gas may be the level of gas dissolved in the water or other liquid.
  • a light communication port allows a transmission of light between the optical sensor input 106 and a remote location 128 outside of the optical sensor system 100 at which the distal end of the fibre with the fluorescent or reflective coating is provided.
  • Light may be transported by an optical fibre 126 from the remote location to a light communication port, or may be emitted from the remote location to the light communication port.
  • a first wavelength or range of wavelengths is reflected at the distal end at a first temperature
  • a second wavelength or range of wavelengths is reflected at the distal end at a second temperature
  • a difference in temperature or an absolute temperature may be determined.
  • a look-up table may be provided by which the ambient parameter may be related to the reflective properties. This will be elaborated on further below.
  • the optical sensor system 100 additionally comprises a sensor driving module 116, in the embodiment as shown in Fig. 1A arranged to drive the optical sensor input 106 over a guiding rail 114.
  • the communication ports are driven along the first axis along the stationary optical sensor input 106. If the optical sensor input 106 is comprised by the optical sensor module 102, the whole optical sensor module 102 may be driven by the sensor driving module 116.
  • Fig. IB shows an embodiment of the optical sensor system 100 wherein the optical sensor input 106 is aligned with the second light communication port 110.
  • the sensor driving module 116 may be arranged as a linear actuator, comprising for example a piston, a linear motor, a spindle or a toothed rack driven by a rotating motor, any other actuator or any
  • first axis 150 is a linear axis.
  • the first axis 150 may be a rotational axis.
  • the sensor driving module 116 may be arranged as a stepper motor, brushed or brushless DC motor, servomotor, any other rotary actuator, or a any combination thereof.
  • the sensor driving module 116 is further arranged to drive the first of the optical sensor input 106 and the plurality of hght communication ports along a second axis (not shown in Figs. 1A and IB).
  • the light communication ports are next to being spaced along the first axis also spaced along the second axis.
  • a sensor driving module 116 arranged to drive the first of the optical sensor input and the plurality of light communication ports along the first and the second axes may comprise two driving modules, wherein a first driving module is arranged to drive the second driving module along the first axis.
  • the first of the optical sensor input and the plurality of hght communication ports may be connected to the second driving module and driveable along the second axis by the second driving module such that the second driving unit and the first of the optical sensor input and the plurality of light communication ports are driven simultaneously by the first driving module along the first axis.
  • first axis 150 and the second axis may be a rotational axes.
  • a first of the first axis 150 and the second axis may be a first of the three orthogonal axes
  • a second of the first axis 150 and the second axis may be a rotational axis around the first of the three orthogonal axes.
  • the addition of driveability over the second axis allows an even more compact optical sensor system to be constructed.
  • An embodiment of the optical sensor system 100 wherein both the first axis 150 and the second axis are rotational axes may also be envisioned.
  • the optical sensor system 100 comprises a light source 118 for providing light to the light communication ports, more specifically to the light communication port with which the optical sensor 104 is aligned.
  • the emitted light may in this way be coupled into the optical fibre 126.
  • the light source 118 is preferably arranged to be drivable by the sensor driving module 116 relative to the plurality of light communication ports, such that it may be driven along with the optical sensor input 106 and may thus be ahgned with a light communication port together with the optical sensor input 106.
  • the light source 118 may be comprised by the optical sensor module 102. Alternatively, it is provided in a separate module.
  • the light provided by the light source 118 may be transported from the light communication port with which the light source 118 is aligned to a remote location 128, for example through an optical fibre 126.
  • the distal end with the reflective coating is provided at the remote location 128.
  • the light source 118 is a (tunable) light source having a narrow band emission spectrum.
  • the light source 118 may be arranged as a laser, one or more LEDs, any other light source or any combination thereof.
  • the embodiment of the optical sensor system 100 as shown in Fig. 1A further comprises a processing unit 120.
  • the processing unit 120 is arranged to at least one of controlling a wavelength of light emitted by the hght source 118 and receiving the data signal generated by the optical sensor 104 in response to receiving light from the light communications port.
  • the embodiment of the optical sensor system 100 as shown in Fig. 1A further comprises a first data storage module 122 for storing expected sensor response data.
  • the expected sensor response data may comprise information on expected intensity of certain wavelengths in the reflected hght or of particular wavelengths or ranges of wavelengths therein, which may correspond to a certain entity or a magnitude thereof.
  • the expected sensor response data may be used for identifying the reflective properties of the fluorescent or reflective coating provided at the distal end of a fibred connected to a light communication port.
  • Fluorescent or reflective coatings may provide their sensitivity to values of specific entities only at particular wavelengths. By sweeping wavelength - varying the wavelength over a particular interval - and monitoring reflected light, a specific response may be detected at a particular wavelength. Such response at the particular wavelength, the responsive wavelength or response wavelength interval, is for example significantly different from a reflective response at other wavelengths. For example, the fluorescence or reflection may be
  • the wavelength or wavelength interval(s) at which the specific response is detected is provided to the processing unit 120 which looks up what entities provide a specific response at the determined wavelength at which the specific response is detected.
  • This information is stored in a second data storage module 124, in a field assigned to the hght
  • the first data storage module 122 and the second data storage module 124 may be the implemented in one and the same physical memory module.
  • This field may comprise at least one record for storing at least one of the wavelength or wavelength interval at which the specific response is detected, an entity of which the reflected light provides an indication of magnitude and a location of the applicable light communication port allowing the processing unit 120 to control the sensor driving module 116 to position the sensor module 102 to the apphcable light communication port.
  • the processing unit 120 may be provided with location data comprising ahgnment data corresponding to whereto the sensor driving module 116 should be controlled in order to align with a specific light communication port.
  • the alignment data may comprise a location on the guiding rail 114, and optionally when the driving module is further arranged to drive along a second axis, as will be elaborated on below, a location on second axis.
  • the location may relate to an angle.
  • the light source 118 may be controlled to provide a different wavelength or range of wavelengths for each of the light communication ports.
  • the wavelength or range of wavelengths associated with a light communication port may be comprised by the location data.
  • Fig. 2A shows an embodiment of the optical sensor system 100 further comprising a fibre driving module 202 for inserting or withdrawing a distal end 205 of an optical probing fibre 204 in or from a medium 206.
  • a medium is for example a water body in for example an aquarium or a breeding pond, soil or another plant breeding substrate, or any other medium in which an optical probing fibre 204 may be inserted or
  • the fibre driving module 204 may comprise an electromotor 212 as an actuator for driving a pulley 214 as a driving element to actuate the probing fibre 204 in a reciprocating way. Also other types of actuators and driving elements may be used. Inside the fibre driving module 202 or, alternatively or additionally, at another location, the optical probing fibre 204 is provided in a loop.
  • the loop may be provided around a reel or other buffer for the optical probing fibre 204.
  • buffer for the optical probing fibre 204.
  • optical probing fibre 204 may be folded several times, in addition to or alternatively to being provided in a loop.
  • the distal end 205 of the optical probing fibre 204 is inserted in the medium by swivelling the optical fibre 204, wherein the swivelling action is actuated by a swivelhng actuator and a swivelling driving element connected to the optical fibre 204.
  • a buffer may be omitted.
  • the optical probing fibre 204 is connected to a light communication port of the optical sensor system 100, such that light may travel between the optical sensor system 100 and the distal end 205 of the optical probing fibre.
  • the distal end 205 of the optical probing fibre need not always to be inserted or immersed within or inside the medium, but only when wanting a measurement is to be performed. This may prevent or reduce a build-up of light blocking or light absorbing matter on the distal end 205 of the optical probing fibre such as algae, dirt, faeces, or any other hght blocking matter which may reduce accuracy of the measurement.
  • Fig. 2A shows the distal end of the optical probing fibre 205 in an inserted state, inserted into the medium 206.
  • Fig. 2B shows the distal end of the optical probing fibre 205 in a withdrawn state, that is not inserted into the medium 206.
  • a fibre driving controller 208 may be provided.
  • the fibre driving controller 208 may be connected to the optical sensor 104 or the processing unit 120.
  • the fibre driving controller 208 may also be incorporated in the processing unit 120.
  • the fibre driving controller 208 may further be arranged to insert withdraw the optical probing fibre 204 from the medium 206 by actuating or operating the electromotor 212 if the data signal satisfies a pre-determined criterion.
  • a pre-determined criterion may be a successful measurement, after which an inserted optical probing fibre 204 in the medium 206 is not required anymore at that time, upon which interrupt the optical probing fibre 204 is withdrawin from the medium.
  • the distal end 205 optical probing fibre 204 may be inserted in the medium 206 at specific time intervals, for example every 10 seconds, every quarter of an hour, every two hours, every twelve hours, every day or at a specific day and time once every week - or more or less frequently.
  • the fibre driving module 202 may be actuated to drive the distal end 205 in the medium 206 based on particular interrupt signals.
  • the interrupt signal may be generated by the processing unit 120 in response to, for example, an alarm signal generated by a further sensor monitoring a state of the medium 206.
  • a further sensor may be a non-optical temperature sensor; if the temperature sensed by the non-optical temperature sensor is outside a safety band, the processing unit may generate the alarm signal.
  • the distal end 205 of the optical probing fibre 204 is inserted in the medium by means of the fibre driving unit 202 and one or measurements are performed.
  • the fibre driving module 202 is provided with a multitude of optical probing fibres 205.
  • a further sensor driving module 116' is provided to the fibre driving module 202.
  • the further sensor driving module 116’ may be provided outside the housing 101.
  • the further sensor driving module 116' may be coupled to the processing unit 120. This implementation does not exclude availability of the sensor driving module 116 within the housing 110 as discussed above.
  • Each of the light communication ports in the housing 110 may be connected to a further sensor driving module like the sensor driving module 116' depicted by Figure 3.
  • the fibre driving module 202 is arranged for driving each of the multitude of the probing fibres 204 in and out of the medium 206.
  • the further driving unit 116’ is arranged to drive a distal end of a further flexible optical fibre 107’ such that the distal end of the further flexible optical fibre 107' is coupled to a proximal end 205 of the optical probing fibre that has been driven or is to be driven in the medium 206.
  • the further flexible fibre 107' is at a proximal end coupled to an optical communication port of the optical sensor system 100 or directly to the optical sensor 104 and/or the light source 118.
  • the processing unit 120 is arranged to control the fibre driving module to drive probing fibres 204 in and out of the medium 206 and the further sensor driving module 116' to drive the further flexible optical fibre 107’ to a probing fibre 204 that is to be used to acquire information on a parameter of the medium 206 - the probing fibre 204 having a distal end in the medium 206.
  • the controlling of the further sensor driving module 116’ to drive the further flexible optical fibre 107' from a first optical probing fibre 204 to a second optical probing fibre 204' or to another optical probing fibre may be done at fixed intervals, for example on a per-day or per-week interval.
  • operation of the further sensor driving module 116' to drive the further flexible optical fibre 107 may be controlled based on a signal received from the optical sensor 106.
  • a connection - optical coupling - between the distal end of the further flexible optical fibre 107’ and the proximal end of the first optical probing fibre 204 within the further sensor driving module 116' is disengaged and a coupling is estabhshed between the further flexible optical fibre 107' and the proximal end of the second optical probing fibre 204’.
  • the coupling in or by the further sensor driving module 116' may be similar or equivalent to the coupling between the optical sensor input 106 and the first light communication port 108 as discussed in conjunction with Figure 1 A.
  • the movement of the distal end of the further optical fibre 107' relative to proximal ends of the first optical probing fibre 204 and the second optical probing fibre 204’ may be executed in one of the various ways discussed.
  • the distal end of the further optical fibre 107' may be interpreted as an optical sensor input or a further optical sensor input; the proximal ends of the optical probing fibres may be interpreted as further light communication ports.
  • the insertion and withdrawals of the distal ends of the first optical probing fibre 204 and the second optical probing fibre 204' may be executed as discussed in conjunction with Figure 2 A.
  • Each of the optical probing fibres 204 held by the further sensor driving module 116' may be provided with its own electromotor or other actuator. Alternatively, one or more actuators are provided that is arranged to actuate multiple optical probing fibres for insertion in and/or withdrawal from the medium 206.
  • the processing unit 120 may be in this implementation be arranged to determine, based on a signal received from the optical sensor 106, whether a change in a signal received from the optical sensor 106, the change is related to deterioration or soiling of the reflective coating at the distal end of the probing fibre 204 or due to a change of a value of the parameter monitored.
  • the time the operational probing fibre 204 is in use may be taken into account as well at this point.
  • a trend in the received signal may be determined, filtering out temporal fluctuations over short intervals.
  • a low pass filter having a low cut off frequency for example at once per hour or once per day. If the processing unit determines 120 that the signal thus filtered satisfies a particular condition, the proving fibre 204 used is changed, from the one currently in use to a new and clean one.
  • the condition may be that the filtered signal is above or below a particular threshold.
  • the embodiments as discussed above in conjunction with Figure 3 may be implemented without the functionality of driving the fibres in and out of the medium 206.
  • the fibre driving module 202 does not comprise the further driving unit 116'.
  • one or more fibres connected to one or more light communication ports of the optical sensor system 100 are connected to the fibre driving module 202.
  • the fibre driving module 202 is arranged for driving the fibres in and out of the medium 206.
  • multiplexing and mechanical multiplexing in particular may take place at the fibre driving module 202, the housing 110 or both.
  • optical fibres may replaced by conductors hke conductive wires.
  • Optical communication ports may provide for conductive, capacitive or inductive coupling between conductive wires.
  • the reflective or fluorescent coatings may be replaced by sensors, the laser by a current or a voltage source and the optical sensor by an input to an electrical detection circuit.
  • an optical sensor system which is arranged to read information from a plurality of hght reflecting surfaces with a single optical sensor unit.
  • the system receives thus a plurality of signals which are mechanically multiplexed towards the sensor by having the sensor movable relative to where the signals enter the system.
  • the sensor may thus be moved and aligned with one of the signals and read out the signal. After having read out the first signal, the sensor is moved towards a second signal which may then be read out.
  • the invention may also be embodied with less components than provided in the embodiments described here, wherein one component carries out multiple functions.
  • the invention be embodied using more elements than depicted in the Figures, wherein functions carried out by one component in the embodiment provided are distributed over multiple components.

Abstract

An optical sensor system (100) is provided which is arranged to read information from a plurality of light emitting or reflecting surfaces with a single optical sensor unit (102). The system (100) receives thus receives a plurality of signals which are mechanically multiplexed towards the sensor unit (102) by having the optical sensor input (106) movable relative to light communication ports (108, 110) where the signals enter the system (100). The optical sensor input (106) may thus be moved and aligned with one of the light communication ports (108, 110) and read out a first signal. After having read out the first signal, the optical sensor input (106) is moved towards a second light communication port (108, 110) which may then be read out. With this system (100), with a single optical sensor unit (102) a plurality of signals from a plurality of light communication ports (108, 110) may be read out which may provide a smaller and less complex system.

Description

Title: Mechanical multiplexing of optical sensor
TECHNICAL FIELD
The various aspects and implementations thereof relate to an optical sensor system.
BACKGROUND
Fluorescent and/or reflective coatings of which optical properties change due to changing parameters in the surroundings of the coating are known. Light reflected or emitted from such a coating may be received by an optical sensor, which may be used for determining information on the parameter in the surrounding of the coating.
More information on such coatings and use thereof may be found in EP1134583, EP1860931, EP1529213 and EP1257810.
SUMMARY
It is preferred to provide an improved optical sensor system.
A first aspect provides an optical sensor system, comprising an optical sensor module comprising an optical sensor and an optical sensor input, the optical sensor being arranged for generating a data signal in response to receiving light received by the optical sensor input, the data signal carrying information related to information carried by the received hght. The optical sensor system further comprises a plurality of light communication ports for providing an emitted or reflected light signal, the hght communication ports being spaced apart along a first axis. The optical sensor system also comprises a driving module, arranged to drive a first of the optical sensor input and the plurality light communication ports along the first axis relative to a second of the optical sensor input and the plurality of light communication ports such that the optical sensor may be aligned with at least a first light communication port and a second light communication port for receiving light from the light communication ports.
An optical sensor system is thus provided capable of receiving an emitted or reflected light signal from a plurality of light communication ports with a single optical sensor input.
An aim of the optical sensor system is to determine at the location of the optical sensor system parameters at a plurality of remote locations or multiple parameters at one or more locations. Remote locations are locations at which the optical sensor system would be unable to measure directly because for example they are too far away or there are obstacles present between the remote location and the optical sensor system which block light travelling directly in a straight line from the remote location to the optical sensor system.
With the ability of the optical sensor system to align a single optical sensor module with a plurality of light communication ports, a simpler and cheaper system may be provided compared to having a single optical sensor module per light communication port. The optical sensor modules are often more expensive and complex than the light
communication ports and it is therefore preferred to have one optical sensor module and a plurality of light communication ports. As an option, an embodiment of the optical sensor system comprising a plurality of optical sensor modules and a single light communication port may be envisioned as well. The light communication ports may be two-way ports, that is they may be arranged to send light and receive light.
In an embodiment of the optical sensor system, the optical sensor module further comprises a light source for providing light to the light communication ports. With the light source provided with the optical sensor system, no external light source is required, and the optical sensor system may be operated in a dark or low light environment. The light source may optionally be a tunable light source having a narrow band emission spectrum that may be tuned. With light having a narrow band emission spectrum, light is meant which comprises a single wavelength, or which acts substantially as if it consist only a single wavelength, for example because it has a very narrow bandwidth, of a few nanometres, for example a maximum bandwidth of 20 nanometres, preferably 10 nanometres and even more preferred 5 nanometres. Such light has the advantage that noise from unwanted wavelengths can be prevented.
An embodiment of the optical sensor system comprises a processing unit arranged to control a wavelength of light emitted by the (tunable) light source. The processing unit may further be arranged for receiving the data signal generated by the optical sensor in response to receiving hght from the light communication port with which the optical sensor is aligned. With tunable hght source, a light source is implied of which the wavelength or ranges of wavelengths emitted can be controlled.
In a preferred embodiment, the optical sensor system comprises a first data storage module for storing expected sensor response data. In such an embodiment, the processing unit is further arranged to control the driving module to ahgn the optical sensor with the first light communication port, control the light source to vary the wavelength over a pre-determined interval, receive the data signal from the optical sensor, retrieve at least part of the expected sensor response data, and determine, based on an outcome of a comparison between the received data signal and the retrieved data, an entity of which a magnitude is represented by the received signal.
An embodiment of the optical sensor system further comprises a second data storage module for storing address information. In such an embodiment, the processing unit may be arranged to store and retrieve data in and from the second data storage module, which data comprises a record comprising a location of a light communication port and a wavelength or range of wavelengths. In embodiments of the optical sensor system, the driving module is further arranged to drive the first of the optical sensor input and the plurality of light communication ports along a second axis relative to the second of the optical sensor input and the plurality of light communication ports. In such an embodiment, the plurality of light communication ports are spaced apart along the first axis and the second axis. Spacing the plurality of light communication ports along the first axis and the second axis allows for a more compact optical sensor system.
In an embodiment of the optical sensor system, the first axis is perpendicular to the second axis. In such an embodiment, both axes are linear axes along which the first of the optical sensor input and the plurality of light communication ports may be translated by the driving module.
Embodiments of the optical sensor system may also be envisioned wherein the first axis is a rotating or curved axis. Such a rotating or curved axis allows for a more compact optical sensor system as the light
communication ports may be provided at different angles relative to the optical sensor input.
Preferably, the optical sensor input is mounted on the driving module such that the driving module is arranged for driving the position of the optical sensor input relative to the plurality of light communication ports. In such an embodiment, the optical sensor input is the first of the optical sensor input and the plurality of light communication ports.
In another embodiment of the optical sensor system, the optical sensor input comprises an optical fibre which is at a proximal end connected to the optical sensor. The optical fibre allows communication of light between the optical sensor and the optical sensor input.
In yet another embodiment of the optical sensor system, the plurality of light communication ports are arranged for receiving an optical fibre. Such an optical fibre allows communication of fight between the light communication port and a remote location. Another embodiment of the optical sensor system comprises a fibre driving module for driving an optical probing fibre, in particular for inserting or with chawing a distal end of the optical probing fibre in or from a medium.
Such an embodiment of the optical sensor system comprising the fibre driving module may further comprise a fibre driving controller arranged to control operation of the fibre driving module and connected to the optical sensor, wherein the fibre driving controller is further arranged to withdraw or bring in the optical probe fibre if the data signal from the fibre or a nearby fibre satisfies a pre-determined criterion.
BRIEF DESCRIPTION OF THE DRAWINGS
The various aspects and embodiments thereof will now be discussed in conjunction with drawings. In the drawings:
Fig. 1A shows an embodiment of an optical sensor system;
Fig. IB shows another embodiment of the optical sensor system;
Fig. 2A shows yet another embodiment of the optical sensor system; and
Fig. 2B shows the optical sensor system with a withdraw optical probing fibre; and
Fig. 3 shows another embodiment of an optical sensor system and a device for inserting fibres in and with chawing fibres from a medium.
DETAILED DESCRIPTION
Fig. 1A shows an embodiment of an optical sensor system 100, comprising an optical sensor module 102. The optical sensor module 102 comprises an optical sensor 104 and an optical sensor input 106, wherein the optical sensor 104 is arranged for generating a data signal in response to hght received via the optical sensor input 106. The data signal carries information related to information carried by the received light. The received light may be communicated from the optical sensor input 106 to the optical sensor 104 through a flexible optical fibre 107. In another
embodiment, the optical sensor input 106 is directly coupled to the optical sensor 104, for example by means of a rigid connection and optionally in a single housing.
Information carried by the received light may relate to properties of the light, such as a light intensity, a range of wavelengths comprised by the light, any other property or a combination thereof. The range of wavelengths may comprise one of more distinct ranges of wavelengths, or may comprise one or more single wavelengths. With light, electromagnetic radiation is meant and light is not restricted to light visible by the human eye (380 nm to 800 nm) and may extend from far infrared (1 millimetre) to far ultraviolet (10 nm). Optionally, a more narrow range may be covered, from approximately 100 nm to 1 mih or from 200 nm to 2 pm.
The optical sensor system 100 may further comprise a housing
101 in which the optical sensor module and driving module are provided. A plurality of light communication ports comprising a first light
communication port 108 and a second light communication port 110 may be provided in one or more sides of the housing. The plurality of hght communication ports is provided such that light may be communicated from and/or to the plurality of light communication ports from outside and inside the housing 101. The housing 101 may be arranged such that light from outside the housing is prevented from reaching the optical sensor input 106, preventing noise in the data signal generated by the optical sensor 104.
The optical sensor system 100 as shown in Fig. 1A comprises the first light communication port 108 and the second light communication port 110 spaced apart along a first axis 150. The optical sensor system 100 may comprise more ports. The light communication ports are arranged for passing through an emitted or reflected light signal. In a preferred embodiment, a light communication port is arranged for receiving a ί proximal end of a fibre, which fibre comprises a fluorescent or reflective coating at a distal end. The light optical properties of the fluorescent or reflective coating change according to ambient parameters of the coating. Such reflecting properties may relate to a fluorescence wavelength, life-time or yield or the reflection coefficient or absorption coefficient changing under the influence of a varying entity at the distal end. Light reflected may have the same wavelength as received by the distal end or one or more different wavelengths.
Alternatively, the fibre received by a communication port is at the distal end connected to a proximal end of a further fibre which carries the fluorescent or reflective coating at its distal end. Ambient parameters represent particular entities, for example be a temperature, pressure, pH level, oxygen level, levels of other substances and gases in particular, any other parameter or any combination thereof. The ambient environment is preferably a fluid containing environment and more in particular a liquid containing environment like water. In the latter case, the level of gas may be the level of gas dissolved in the water or other liquid.
A light communication port allows a transmission of light between the optical sensor input 106 and a remote location 128 outside of the optical sensor system 100 at which the distal end of the fibre with the fluorescent or reflective coating is provided. Light may be transported by an optical fibre 126 from the remote location to a light communication port, or may be emitted from the remote location to the light communication port.
In an example of a reflecting coating arranged to have changing reflective properties under the influence of a varying temperature, a first wavelength or range of wavelengths is reflected at the distal end at a first temperature, and a second wavelength or range of wavelengths is reflected at the distal end at a second temperature.
From the difference between the first wavelength of range of wavelengths and the second wavelength of range of wavelengths, a difference in temperature or an absolute temperature may be determined. Alternatively or additionally, a look-up table may be provided by which the ambient parameter may be related to the reflective properties. This will be elaborated on further below.
The optical sensor system 100 additionally comprises a sensor driving module 116, in the embodiment as shown in Fig. 1A arranged to drive the optical sensor input 106 over a guiding rail 114. In an alternative embodiment, the communication ports are driven along the first axis along the stationary optical sensor input 106. If the optical sensor input 106 is comprised by the optical sensor module 102, the whole optical sensor module 102 may be driven by the sensor driving module 116.
This allows the optical sensor input 106 to be aligned with the first light communication port 108 and the second light communication port 110 for receiving hght from the light communication port with which it is aligned, which in Fig. 1A is the first light communication port 108. Fig. IB shows an embodiment of the optical sensor system 100 wherein the optical sensor input 106 is aligned with the second light communication port 110.
The sensor driving module 116 may be arranged as a linear actuator, comprising for example a piston, a linear motor, a spindle or a toothed rack driven by a rotating motor, any other actuator or any
combination thereof in case the first axis 150 is a linear axis.
Alternatively, the first axis 150 may be a rotational axis. In such a case, the sensor driving module 116 may be arranged as a stepper motor, brushed or brushless DC motor, servomotor, any other rotary actuator, or a any combination thereof.
In an embodiment of the optical sensor system 100, the sensor driving module 116 is further arranged to drive the first of the optical sensor input 106 and the plurality of hght communication ports along a second axis (not shown in Figs. 1A and IB). In such an embodiment, the light communication ports are next to being spaced along the first axis also spaced along the second axis.
A sensor driving module 116 arranged to drive the first of the optical sensor input and the plurality of light communication ports along the first and the second axes may comprise two driving modules, wherein a first driving module is arranged to drive the second driving module along the first axis.
The first of the optical sensor input and the plurality of hght communication ports may be connected to the second driving module and driveable along the second axis by the second driving module such that the second driving unit and the first of the optical sensor input and the plurality of light communication ports are driven simultaneously by the first driving module along the first axis.
Alternatively , one or both of the first axis 150 and the second axis may be a rotational axes. Considering a three-dimensional space spanned by three orthogonal axes, a first of the first axis 150 and the second axis may be a first of the three orthogonal axes, and a second of the first axis 150 and the second axis may be a rotational axis around the first of the three orthogonal axes. The addition of driveability over the second axis allows an even more compact optical sensor system to be constructed. An embodiment of the optical sensor system 100 wherein both the first axis 150 and the second axis are rotational axes may also be envisioned.
Preferably, the optical sensor system 100 comprises a light source 118 for providing light to the light communication ports, more specifically to the light communication port with which the optical sensor 104 is aligned. The emitted light may in this way be coupled into the optical fibre 126.
The light source 118 is preferably arranged to be drivable by the sensor driving module 116 relative to the plurality of light communication ports, such that it may be driven along with the optical sensor input 106 and may thus be ahgned with a light communication port together with the optical sensor input 106. As such, the light source 118 may be comprised by the optical sensor module 102. Alternatively, it is provided in a separate module.
The light provided by the light source 118 may be transported from the light communication port with which the light source 118 is aligned to a remote location 128, for example through an optical fibre 126. The distal end with the reflective coating is provided at the remote location 128.
In an embodiment, the light source 118 is a (tunable) light source having a narrow band emission spectrum. The light source 118 may be arranged as a laser, one or more LEDs, any other light source or any combination thereof.
The embodiment of the optical sensor system 100 as shown in Fig. 1A further comprises a processing unit 120. The processing unit 120 is arranged to at least one of controlling a wavelength of light emitted by the hght source 118 and receiving the data signal generated by the optical sensor 104 in response to receiving light from the light communications port.
The embodiment of the optical sensor system 100 as shown in Fig. 1A further comprises a first data storage module 122 for storing expected sensor response data. The expected sensor response data may comprise information on expected intensity of certain wavelengths in the reflected hght or of particular wavelengths or ranges of wavelengths therein, which may correspond to a certain entity or a magnitude thereof.
The expected sensor response data may be used for identifying the reflective properties of the fluorescent or reflective coating provided at the distal end of a fibred connected to a light communication port. Fluorescent or reflective coatings may provide their sensitivity to values of specific entities only at particular wavelengths. By sweeping wavelength - varying the wavelength over a particular interval - and monitoring reflected light, a specific response may be detected at a particular wavelength. Such response at the particular wavelength, the responsive wavelength or response wavelength interval, is for example significantly different from a reflective response at other wavelengths. For example, the fluorescence or reflection may be
significantly lower or higher, at the wavelength provided by the light source 118 or at one or more other specific wavelengths or wavelength intervals.
The wavelength or wavelength interval(s) at which the specific response is detected is provided to the processing unit 120 which looks up what entities provide a specific response at the determined wavelength at which the specific response is detected. This information is stored in a second data storage module 124, in a field assigned to the hght
communication port to which the optical sensor input 106 is coupled. The first data storage module 122 and the second data storage module 124 may be the implemented in one and the same physical memory module.
This field may comprise at least one record for storing at least one of the wavelength or wavelength interval at which the specific response is detected, an entity of which the reflected light provides an indication of magnitude and a location of the applicable light communication port allowing the processing unit 120 to control the sensor driving module 116 to position the sensor module 102 to the apphcable light communication port.
To control the sensor driving module 116 to ahgn the optical sensor 104 with the first light communication port 111, the processing unit 120 may be provided with location data comprising ahgnment data corresponding to whereto the sensor driving module 116 should be controlled in order to align with a specific light communication port.
The alignment data may comprise a location on the guiding rail 114, and optionally when the driving module is further arranged to drive along a second axis, as will be elaborated on below, a location on second axis. When one or both of the first axis 150 and the second axis are rotational axes, the location may relate to an angle.
The light source 118 may be controlled to provide a different wavelength or range of wavelengths for each of the light communication ports. The wavelength or range of wavelengths associated with a light communication port may be comprised by the location data.
Fig. 2A shows an embodiment of the optical sensor system 100 further comprising a fibre driving module 202 for inserting or withdrawing a distal end 205 of an optical probing fibre 204 in or from a medium 206. Such a medium is for example a water body in for example an aquarium or a breeding pond, soil or another plant breeding substrate, or any other medium in which an optical probing fibre 204 may be inserted or
withdrawn.
The fibre driving module 204 may comprise an electromotor 212 as an actuator for driving a pulley 214 as a driving element to actuate the probing fibre 204 in a reciprocating way. Also other types of actuators and driving elements may be used. Inside the fibre driving module 202 or, alternatively or additionally, at another location, the optical probing fibre 204 is provided in a loop.
Optionally, the loop may be provided around a reel or other buffer for the optical probing fibre 204. In such buffer, alternatively or
additionally, the optical probing fibre 204 may be folded several times, in addition to or alternatively to being provided in a loop. In another
implementation, the distal end 205 of the optical probing fibre 204 is inserted in the medium by swivelling the optical fibre 204, wherein the swivelling action is actuated by a swivelhng actuator and a swivelling driving element connected to the optical fibre 204. In this implementation, a buffer may be omitted.
At a proximal end, the optical probing fibre 204 is connected to a light communication port of the optical sensor system 100, such that light may travel between the optical sensor system 100 and the distal end 205 of the optical probing fibre.
By being able to insert and withdraw the distal end 205 of the optical probing fibre, the distal end 205 of the optical probing fibre need not always to be inserted or immersed within or inside the medium, but only when wanting a measurement is to be performed. This may prevent or reduce a build-up of light blocking or light absorbing matter on the distal end 205 of the optical probing fibre such as algae, dirt, faeces, or any other hght blocking matter which may reduce accuracy of the measurement.
Fig. 2A shows the distal end of the optical probing fibre 205 in an inserted state, inserted into the medium 206. Fig. 2B shows the distal end of the optical probing fibre 205 in a withdrawn state, that is not inserted into the medium 206.
To control operation of the fibre driving module 202, a fibre driving controller 208 may be provided. The fibre driving controller 208 may be connected to the optical sensor 104 or the processing unit 120. The fibre driving controller 208 may also be incorporated in the processing unit 120. The fibre driving controller 208 may further be arranged to insert withdraw the optical probing fibre 204 from the medium 206 by actuating or operating the electromotor 212 if the data signal satisfies a pre-determined criterion. Such a pre-determined criterion may be a successful measurement, after which an inserted optical probing fibre 204 in the medium 206 is not required anymore at that time, upon which interrupt the optical probing fibre 204 is withdrawin from the medium.
The distal end 205 optical probing fibre 204 may be inserted in the medium 206 at specific time intervals, for example every 10 seconds, every quarter of an hour, every two hours, every twelve hours, every day or at a specific day and time once every week - or more or less frequently.
Additionally or alternatively, the fibre driving module 202 may be actuated to drive the distal end 205 in the medium 206 based on particular interrupt signals.
The interrupt signal may be generated by the processing unit 120 in response to, for example, an alarm signal generated by a further sensor monitoring a state of the medium 206. For example, such further sensor may be a non-optical temperature sensor; if the temperature sensed by the non-optical temperature sensor is outside a safety band, the processing unit may generate the alarm signal. In response to the alarm signal, the distal end 205 of the optical probing fibre 204 is inserted in the medium by means of the fibre driving unit 202 and one or measurements are performed.
In an alternative embodiment, as depicted by Figure 3, the fibre driving module 202 is provided with a multitude of optical probing fibres 205. To the fibre driving module 202, a further sensor driving module 116' is provided. Rather than being provided in the housing 101, the further sensor driving module 116’ may be provided outside the housing 101.
The further sensor driving module 116' may be coupled to the processing unit 120. This implementation does not exclude availability of the sensor driving module 116 within the housing 110 as discussed above. Each of the light communication ports in the housing 110 may be connected to a further sensor driving module like the sensor driving module 116' depicted by Figure 3.
In this embodiment, the fibre driving module 202 is arranged for driving each of the multitude of the probing fibres 204 in and out of the medium 206. The further driving unit 116’ is arranged to drive a distal end of a further flexible optical fibre 107’ such that the distal end of the further flexible optical fibre 107' is coupled to a proximal end 205 of the optical probing fibre that has been driven or is to be driven in the medium 206. The further flexible fibre 107' is at a proximal end coupled to an optical communication port of the optical sensor system 100 or directly to the optical sensor 104 and/or the light source 118. The processing unit 120 is arranged to control the fibre driving module to drive probing fibres 204 in and out of the medium 206 and the further sensor driving module 116' to drive the further flexible optical fibre 107’ to a probing fibre 204 that is to be used to acquire information on a parameter of the medium 206 - the probing fibre 204 having a distal end in the medium 206.
The controlling of the further sensor driving module 116’ to drive the further flexible optical fibre 107' from a first optical probing fibre 204 to a second optical probing fibre 204' or to another optical probing fibre may be done at fixed intervals, for example on a per-day or per-week interval.
Additionally or additionally, operation of the further sensor driving module 116' to drive the further flexible optical fibre 107 may be controlled based on a signal received from the optical sensor 106.
In one implementation, if a signal reflected or otherwise provided by the distal end 205 of the optical probing fibre 204 weakens, has an decreasing signal to noise ratio or otherwise deteriorates, a connection - optical coupling - between the distal end of the further flexible optical fibre 107’ and the proximal end of the first optical probing fibre 204 within the further sensor driving module 116' is disengaged and a coupling is estabhshed between the further flexible optical fibre 107' and the proximal end of the second optical probing fibre 204’.
The coupling in or by the further sensor driving module 116' may be similar or equivalent to the coupling between the optical sensor input 106 and the first light communication port 108 as discussed in conjunction with Figure 1 A. The movement of the distal end of the further optical fibre 107' relative to proximal ends of the first optical probing fibre 204 and the second optical probing fibre 204’ may be executed in one of the various ways discussed. In the implementation of Figure 3, the distal end of the further optical fibre 107' may be interpreted as an optical sensor input or a further optical sensor input; the proximal ends of the optical probing fibres may be interpreted as further light communication ports.
The insertion and withdrawals of the distal ends of the first optical probing fibre 204 and the second optical probing fibre 204' may be executed as discussed in conjunction with Figure 2 A. Each of the optical probing fibres 204 held by the further sensor driving module 116' may be provided with its own electromotor or other actuator. Alternatively, one or more actuators are provided that is arranged to actuate multiple optical probing fibres for insertion in and/or withdrawal from the medium 206.
The processing unit 120 may be in this implementation be arranged to determine, based on a signal received from the optical sensor 106, whether a change in a signal received from the optical sensor 106, the change is related to deterioration or soiling of the reflective coating at the distal end of the probing fibre 204 or due to a change of a value of the parameter monitored. The time the operational probing fibre 204 is in use may be taken into account as well at this point.
Alternatively or additionally, a trend in the received signal may be determined, filtering out temporal fluctuations over short intervals.
Worded differently, a low pass filter having a low cut off frequency, for example at once per hour or once per day, is applied. If the processing unit determines 120 that the signal thus filtered satisfies a particular condition, the proving fibre 204 used is changed, from the one currently in use to a new and clean one. The condition may be that the filtered signal is above or below a particular threshold.
It is noted that the embodiments as discussed above in conjunction with Figure 3 may be implemented without the functionality of driving the fibres in and out of the medium 206. In yet another embodiment, the fibre driving module 202 does not comprise the further driving unit 116'. In the latter embodiment, one or more fibres connected to one or more light communication ports of the optical sensor system 100 are connected to the fibre driving module 202. The fibre driving module 202 is arranged for driving the fibres in and out of the medium 206.
Hence, multiplexing and mechanical multiplexing in particular may take place at the fibre driving module 202, the housing 110 or both.
Additionally or alternatively to the filtering, other conditions may be applied, for example if the value of the signal received is above or below a particular threshold for a pre-determined amount of time, it is determined that that probing fibre 204 should be changed as discussed above.
The various aspects and implementations thereof described above have been discussed in conjunction with optical signals, optical sensors and optical actuators. It is noted that the various aspects and implementations thereof may also be used in implementations with electrical signals as data carriers. In such implementations, optical fibres may replaced by conductors hke conductive wires. Optical communication ports may provide for conductive, capacitive or inductive coupling between conductive wires. The reflective or fluorescent coatings may be replaced by sensors, the laser by a current or a voltage source and the optical sensor by an input to an electrical detection circuit.
In summary, the various aspects and implementations relate to an optical sensor system is provided which is arranged to read information from a plurality of hght reflecting surfaces with a single optical sensor unit. The system receives thus a plurality of signals which are mechanically multiplexed towards the sensor by having the sensor movable relative to where the signals enter the system. The sensor may thus be moved and aligned with one of the signals and read out the signal. After having read out the first signal, the sensor is moved towards a second signal which may then be read out. With this system, with a single optical sensor a plurality of signals may be read out which may provide a smaller and less complex system. In the description above, it will be understood that when an element such as layer, region or substrate is referred to as being“on” or “onto” another element, the element is either directly on the other element, or intervening elements may also be present. Also, it will be understood that the values given in the description above, are given by way of example and that other values may be possible and/or may be strived for.
Furthermore, the invention may also be embodied with less components than provided in the embodiments described here, wherein one component carries out multiple functions. Just as well may the invention be embodied using more elements than depicted in the Figures, wherein functions carried out by one component in the embodiment provided are distributed over multiple components.
It is to be noted that the figures are only schematic
representations of embodiments of the invention that are given by way of non-limiting examples. For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. The word‘comprising’ does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words 'a’ and 'an' shall not be construed as limited to 'only one', but instead are used to mean 'at least one', and do not exclude a plurality.
A person skilled in the art will readily appreciate that various parameters and values thereof disclosed in the description may be modified and that various embodiments disclosed and/or claimed may be combined without departing from the scope of the invention.
It is stipulated that the reference signs in the claims do not limit the scope of the claims, but are merely inserted to enhance the legibility of the claims.

Claims

Claims
1. Optical sensor system comprising:
An optical sensor module comprising an optical sensor and an optical sensor input, the optical sensor being arranged for generating a data signal in response to a light received via the optical sensor input, the data signal carrying information related to information carried by the received light;
A plurality of light communication ports for passing through an emitted or reflected light signal, the light communication ports being spaced apart along a first axis;
A driving module, arranged to drive a first of the optical sensor input and the plurality light communication ports along the first axis relative to a second of the optical sensor input and the plurality of hght communication ports such that the optical sensor may be aligned with at least a first light communication port and a second light communication port for receiving light from the light communication ports.
2. Optical sensor system according to claim 1, wherein the optical sensor module further comprises a light source for providing light to the hght communication ports.
3. Optical sensor system according to claim 2, wherein the light source is a tunable light source having a narrow band emission spectrum that may be tuned.
4. Optical sensor system according to claim 3, further comprising a processing unit arranged to control a wavelength of hght emitted by the tunable light source and for receiving the data signal generated by the optical sensor in response to receiving light from the light communications port.
5. Optical sensor system according to claim 4, further comprising a first data storage module for storing expected sensor response data, wherein the processing unit is further arranged to:
Control the driving module to ahgn the optical sensor input with the first light communication port;
Control the light source to vary the wavelength over a pre-determined
interval;
Receive the data signal from the optical sensor;
Retrieve at least part of the expected sensor response data;
Determine, based on an outcome of a comparison between the received data signal and the retrieved data, an entity of which a magnitude is represented by the received signal.
6. Optical sensor system according to claim 4 or claim 5, further comprising a second data storage module for storing address information, wherein the processing unit is arranged to store and retrieve data in and from the second data storage module, which data comprises at least one record comprising at least one of a location of a light communication port, an entity and a wavelength or wavelength interval.
7. Optical sensor system according to claim 6, wherein the record further comprises an entity.
8. Optical sensor system according to any of the preceding claims, wherein the driving module is further arranged to drive the first of the optical sensor input and the plurality of light
communication ports along a second axis relative to the second of the optical sensor input and the plurality of light communication ports and the plurality of light communication ports are spaced apart along the second axis.
9. Optical sensor system according to claim 8, wherein the second axis is perpendicular to first axis.
10. Optical sensor system according to any of the preceding claims, wherein the first axis is a rotating or curved axis.
11. Optical sensor system according to any of the claims 8 to 10,
wherein the optical sensor input is mounted on the driving module such that the driving module is arranged for driving the position of the optical sensor input relative to the plurality of light communication ports.
12. Optical sensor system according to any of the preceding claims, wherein the optical sensor input comprises an optical fibre which is at a proximal end connected to the optical sensor.
13. Optical sensor system according to any of the preceding claims, wherein the plurality of light communication ports are arranged for receiving an optical fibre.
14. Optical sensor system according to claim 13, further comprising a fibre driving module for driving an optical probing fibre, in particular for inserting or withdrawing a distal end of the optical probing fibre in or from a medium.
15. Optical sensor system according to claim 14, further comprising a fibre driving controller arranged to control operation of the fibre driving module and connected to the optical sensor, wherein the fibre driving controller is further arranged to withdraw the optical probing fibre from the medium if the data signal satisfies a pre determined criterion.
16. Optical sensor system according to claim 15, wherein the pre
determined criterion is at least one of the following:
the signal to noise ratio of the signal less than a pre-determined value;
the value of the signal value more or less than a pre-determined value;
a measurement value is successfully obtained by means of the optical sensor.
17. Optical sensor system according to claim 15 or claim 16, wherein the fibre driving controller is arranged to operate the fibre driving- module to insert the optical probing fibre in the medium if a criterion is met.
18. Optical sensor system according to claim 17, wherein the pre
determined criterion is at least one of:
- lapse of a pre-determined time interval;
receiving an interrupt signal by the fibre driving controller, in particular an interrupt signal generated based on a signal generated by a further sensor monitoring an entity characteristic of the medium.
19. Optical sensor system according to any of the preceding claims, wherein a processing unit comprised by the system is arranged control the driving module to ahgn the optical sensor input from a first light communication port to a second light communication port if the processing unit determines that a pre-determined criterion is met.
20. Optical sensor system according to claim 19, wherein the
processing unit is arranged to receive a data signal from the optical sensor and the pre-determined criterion is at least one of the following:
The signal to noise ratio of the signal less than a pre-determined value;
The value of the signal value more or less than a pre-determined value.
21. Optical sensor system according to claim 19, wherein the pre determined criterion is lapse of a time interval, in particular a pre-determined time interval.
22. Optical sensor system according to claim 14 or claim 15, wherein the fibre driving module comprises a buffer for the fibre.
PCT/NL2019/050522 2018-08-08 2019-08-08 Mechanical multiplexing of optical sensor WO2020032798A1 (en)

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NL2021441A NL2021441B1 (en) 2018-08-08 2018-08-08 Mechanical multiplexing of optical sensor

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