WO2016067228A1 - Sensor for measuring surface moisture on an uneven surface - Google Patents

Sensor for measuring surface moisture on an uneven surface Download PDF

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Publication number
WO2016067228A1
WO2016067228A1 PCT/IB2015/058338 IB2015058338W WO2016067228A1 WO 2016067228 A1 WO2016067228 A1 WO 2016067228A1 IB 2015058338 W IB2015058338 W IB 2015058338W WO 2016067228 A1 WO2016067228 A1 WO 2016067228A1
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WO
WIPO (PCT)
Prior art keywords
light
photodiode
moisture
sensor
laser diode
Prior art date
Application number
PCT/IB2015/058338
Other languages
French (fr)
Inventor
Domen HUDOKLIN
Samo BEGUŠ
Gaber BEGEŠ
Janko DRNOVŠEK
Original Assignee
Univerza V Ljubljani, Fakulteta Za Elektrotehniko
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Univerza V Ljubljani, Fakulteta Za Elektrotehniko filed Critical Univerza V Ljubljani, Fakulteta Za Elektrotehniko
Publication of WO2016067228A1 publication Critical patent/WO2016067228A1/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
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3554—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for determining moisture content
    • 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
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G01N21/3151—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths using two sources of radiation of different wavelengths
    • 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
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
    • G01N21/474—Details of optical heads therefor, e.g. using optical fibres
    • G01N2021/4742—Details of optical heads therefor, e.g. using optical fibres comprising optical fibres
    • G01N2021/475—Bifurcated bundle
    • 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
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3563—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing solids; Preparation of samples therefor
    • 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
    • G01N2201/06—Illumination; Optics
    • G01N2201/069—Supply of sources
    • 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

Definitions

  • a sensor for measuring moisture on an uneven surface that provides for simple, rapid and efficient measurement of moisture on a surface of objects having uneven geometry.
  • the technical problem that is solved by the present invention is how to realize a sensor for simple, rapid and efficient measurement of moisture on a surface of objects having uneven geometry in batch production, wherein the sensor is to be composed of commercially available components having a favourable price.
  • the near infrared spectroscopy as mentioned above proved to be very adequate in this relation. It provides measurement based on the reflected or transferred infrared light, i. e. the part of the light that does not get absorbed.
  • the light source and a light sensor are arranged at the same side of an object, whereas the light source in the second case is arranged at one side of an object and a light sensor at the other.
  • the most suitable way of measuring superficial moisture on non-transparent objects of low thickness is the measurement of reflected light.
  • Two measurements at various wavelengths of light are needed for the measurement of moisture in a majority of spectroscopic methods, namely in the absorption band of moisture (measuring wavelength) and at a wavelength, in which light absorption does not take place due to moisture (reference wavelength); the content of moisture can be calculated from a ratio between a signal of the reflected light of the reference wavelength and a signal of the reflected light of the measuring wavelength.
  • the light losses not linked to absorption are thus compensated. These losses include scattering of the light from an object, influence of ambient light, colour of an object and dust. It is very favourable for a variety reasons that the selected reference wavelength is close to the measuring wavelength yet outside of the absorption band.
  • two different light sources are needed - in a majority of cases two laser diodes - that radiate the light of these wavelengths.
  • the diodes are electrically modulated; this means that the light is modulated at two frequencies, namely one frequency modulates the reference wavelength and the other frequency modulates the measuring wavelength. This is used to avoid interference with the ambient light (100 Hz) and supply voltage (50 Hz) and to eliminate noise.
  • the light travels from a source through an optical conductor to an optical element (mirror, prism), wherefrom it is projected onto an object, the moisture of which is to be measured.
  • the light reflected from the object is captured by an optical element (mirror, prism), the light is then transferred through the optical conductor to a light sensor that is most often a photodiode (Si, PbS or InGaAs).
  • a light sensor that is most often a photodiode (Si, PbS or InGaAs).
  • the light signal is converted into an electrical signal that is amplified in a lock-in amplifier, where it gets demodulated, wherewith the influence of ambient light is eliminated.
  • the signal then travels into a data acquisition device and it is then further guided to a device for processing data, displaying the measurement results and controlling the measurement method (e. g. a personal computer).
  • Each of laser diodes is modulated by means of a controller or regulator (of electric current or power) connected between the device for data acquisition and the laser diode.
  • the technical solution disclosed in patent application WO 2006/118619 Al allows measuring of moisture on large surfaces, namely on a "continuous" paper on a machine for producing paper.
  • the sensor comprises an optical head, in which infrared light travels along an optical fibre from a light source to a mirror, where it reflects onto the paper. The reflected infrared light therefrom is reflected again from the mirror and continues along another optical fibre to a photodiode. Since the incident light and the reflected light are not on the same axis, the head's configuration is not suitable for measuring the moisture on the surface of uneven objects especially of smaller sizes. Moreover, a Peltier cooler is needed to cool the light source.
  • the system for measuring moisture according to patent application No. EP 2028476 Al is used to measure moisture on the surface of large-size objects, for instance on a sheet of paper or various boards.
  • the system measures the moisture content profile, for which both the reflection of infrared light and transmission of the infrared light through the paper are used. This measurement requires two optical heads and access from both sides of the paper.
  • the system is therefore not suitable for measuring moisture on the surface of small-size uneven objects.
  • a further disadvantage of the system is its high level of complexity, it uses mirrors and lenses that are subject to mechanical creeping and therefore cause imprecise measurements.
  • a sensor for measuring moisture on an uneven surface of the invention that has a special optical link between a light source and an object for simple, rapid and efficient measurement of moisture on the surface of objects having uneven geometry.
  • the sensor for measuring moisture is formed of a laser diode module comprising two laser diodes, a first photodiode, a second photodiode, a lock-in amplifier of the first photodiode, a lock-in amplifier of the second photodiode, a power regulator of the laser diode, an optical link, a module for data acquisition and a device for processing data, displaying measuring results and controlling the measurement method.
  • the laser diode module is formed of two laser diodes each radiating infrared light of a different wavelength: one radiates the light of the so-called measuring wavelength and another radiates the light of the so-called reference wavelength.
  • Said optical link is comprised of a main light guide and two legs in the form of light fibres.
  • the main light guide that comprises light fibres optically links the light source and an object, the moisture of which is to be measured.
  • One fibre of the main light guide a first leg, bifurcates from the main light guide such that it optically links the light source and a light sensor - it transfers the light radiated by the light source.
  • a second leg in the form of a light fibre joins the main light guide such that it optically links the light sensor and the object. This light fibre transfers the light reflected from the object.
  • Each of the bifurcated light fibres guides the light to the light sensor: the first leg guides it to the first light sensor and the second leg guides it to the second light sensor.
  • the light source in this case is two laser diodes and the light sensor is two photodiodes.
  • the optical link not only allows measurement of the moisture on the surface of small- size objects having uneven geometry but also allows for compensation of instability of the light source due to the influence of temperature - it is a known fact that the optical power of laser light is rather temperature-dependent - and for compensation of the instability of light source due to mechanical influences. This is carried out in a way that the first leg transfers the light from the light source to the light sensor where the light is measured. The second leg guides the light reflected from the object to the light sensor. The instabilities or the noise measured in the light from the first leg (light source) are also measured in the light from the second leg (object). The instabilities thus get compensated.
  • Figure 1 a schematic view of a sensor
  • Figure 2 a schematic view of an optical link.
  • a sensor 1 for measuring moisture is formed of a laser diode module 2 comprising two laser diodes 3; a first photodiode 4; a second photodiode 5; a lock-in amplifier 6 of the first photodiode; a lock-in amplifier 7 of the second photodiode; a power regulator 8 of the laser diode; an optical link 11 that optically links the laser diode 3 with an object 14 to be measured, wherein a first leg 15 in the form of a light fibre is bifurcated from a main light guide 12, which guides the light from the laser diode 3 to the first photodiode 4, whereas a second leg 16 in the form of a light fibre connects to the main light guide 12 and guides the light reflected from the object 14 to the second photodiode 5; a module 9 for data acquisition; and a device 10 for processing data, displaying measurement results and controlling the method of measurement.
  • Said optical link 11 is comprised of the main light guide 12 and two legs in the form of light fibres.
  • the main light guide 12 which comprises light fibres 13 optically links the light source 3 and the object 14, the moisture of which is to be measured.
  • One fibre of the main light guide 12, the first leg 15, is bifurcated from the main light guide 12, such that it optically links the light source 3 and the light sensor 4, and transfers the light radiated by the light source 3.
  • the second leg 16 in the form of a light fibre joins the main light guide 12 in a way to optically link the light sensor 5 and the object 14. This light fibre transfers the light reflected from the object 14.
  • Each of the bifurcated light fibres guides the light to the light sensor 4, 5, namely the first leg 15 to the first light sensor 4 and the second leg 16 to the second light sensor 5.
  • the light source 3 in this case is the laser diodes and the light sensor 4, 5 is the two photodiodes.
  • the sensor can be adapted to be suitable for measuring moisture on the surface of objects that are preferably not from a polymeric material. It can also be adapted for the measurement of other substances, preferably liquids, on the surface of objects.

Abstract

A sensor (1) for measuring moisture is formed of a laser diode module (2) comprising two laser diodes (3), a first photodiode (4), a second photodiode (5), a lock-in amplifier (6) of the first photodiode, a lock-in amplifier (7) of the second photodiode, a power regulator (8) of the laser diode, an optical link (11), a module (9) for data acquisition, and a device (10) for processing data, displaying measurement results and controlling the method of measurement, wherein the optical link (11) is provided with a first leg (15) that optically links the laser diode (3) and the first photodiode (4), wherewith it provides for compensation of instability of the laser diode (3) due to temperature and mechanical influences.

Description

SENSOR FOR MEASURING SURFACE MOISTURE ON AN UNEVEN
SURFACE
Object of Invention
A sensor for measuring moisture on an uneven surface that provides for simple, rapid and efficient measurement of moisture on a surface of objects having uneven geometry.
Technical Problem
The technical problem that is solved by the present invention is how to realize a sensor for simple, rapid and efficient measurement of moisture on a surface of objects having uneven geometry in batch production, wherein the sensor is to be composed of commercially available components having a favourable price.
Prior Art
Moisture is an important factor in processes of a vast variety of industrial branches such as pharmacy, food industry, civil engineering, paper industry, textile industry, production of polymeric films etc. It usually occurs as a residue in intermediate phases or at the end of a process. Moisture is undesired in some instances, whereas it is a must in some other instances but it is most often allowed yet in precisely defined limits. This is the reason why various ways of measuring moisture in materials and devices therefor have been developed quite a long time ago. There exist measuring methods that are based on various physical principles such as resistance measurement, radiofrequency measurement, impedance measurement, capacitive measurement, micro wave measurement, nuclear magnetic resonance based measurement. All these methods share at least one of the following disadvantages: imprecision, sophisticated calibration, demanding preparation of a sample for measurement, contact with the sample, measurement of total moisture only or moisture profile and not measurement of moisture on a surface, complex and expensive equipment. A rapid development of optics in the mid-1950s saw the introduction of spectrophotometry in near infrared spectrum of light which eliminated quite many of the above-mentioned disadvantages. The fact is that water molecules are capable of absorbing light in the infrared or near infrared region of the electromagnetic spectrum. It is typical of water to absorb mainly in the mid-infrared region, wherein the most characteristic absorption peaks are about 1400 nm and 1900 nm which are also most often used in the measuring technique. In fact, the light source of the mentioned wavelengths is used to illuminate an object or a material, whose moisture content is to be measured. The higher the moisture content, the more light is absorbed and the less light is reflected from an object and penetrates through it.
In industry, there is a growing need for measuring moisture on a surface or in shallow depths close to the surface. The influence of moisture in a superficial layer, the thickness of which does not exceed 1 mm, is very important in certain cases. One of such cases is adhesion to small polymeric components of electric motors that are used in automobile industry. Since this is the case of mass production, where the quality of adhesion is of key importance in order to reduce scrap and the costs relating thereto, the moisture on the surface of an object needs to be maintained in precisely defined limits and measuring equipment or rather a sensor is needed that allows for a reliable, precise, accurate and repeatable measurement of moisture on the surface or close to the surface.
The near infrared spectroscopy as mentioned above proved to be very adequate in this relation. It provides measurement based on the reflected or transferred infrared light, i. e. the part of the light that does not get absorbed. In the first case, the light source and a light sensor are arranged at the same side of an object, whereas the light source in the second case is arranged at one side of an object and a light sensor at the other. The most suitable way of measuring superficial moisture on non-transparent objects of low thickness is the measurement of reflected light. Two measurements at various wavelengths of light are needed for the measurement of moisture in a majority of spectroscopic methods, namely in the absorption band of moisture (measuring wavelength) and at a wavelength, in which light absorption does not take place due to moisture (reference wavelength); the content of moisture can be calculated from a ratio between a signal of the reflected light of the reference wavelength and a signal of the reflected light of the measuring wavelength. In this way, the light losses not linked to absorption are thus compensated. These losses include scattering of the light from an object, influence of ambient light, colour of an object and dust. It is very favourable for a variety reasons that the selected reference wavelength is close to the measuring wavelength yet outside of the absorption band. To provide the light of two various wavelengths two different light sources are needed - in a majority of cases two laser diodes - that radiate the light of these wavelengths. The diodes are electrically modulated; this means that the light is modulated at two frequencies, namely one frequency modulates the reference wavelength and the other frequency modulates the measuring wavelength. This is used to avoid interference with the ambient light (100 Hz) and supply voltage (50 Hz) and to eliminate noise. The light travels from a source through an optical conductor to an optical element (mirror, prism), wherefrom it is projected onto an object, the moisture of which is to be measured. The light reflected from the object is captured by an optical element (mirror, prism), the light is then transferred through the optical conductor to a light sensor that is most often a photodiode (Si, PbS or InGaAs). Here, the light signal is converted into an electrical signal that is amplified in a lock-in amplifier, where it gets demodulated, wherewith the influence of ambient light is eliminated. The signal then travels into a data acquisition device and it is then further guided to a device for processing data, displaying the measurement results and controlling the measurement method (e. g. a personal computer). Each of laser diodes is modulated by means of a controller or regulator (of electric current or power) connected between the device for data acquisition and the laser diode.
Known technical solutions have many disadvantages. Specially designed measuring equipment is used, especially spectrometers, that is very expensive. Measuring heads are cumbersome and contain movable mechanical parts, additional sensitive optical parts (mirrors, lenses, prisms) that need to be adjusted and are mostly intended to measure moisture on huge even surfaces (paper industry, textile industry). If a halogen lamp (white light of all spectra) is used as a light source instead of a laser diode, narrow-band filters are needed (such as a disk with filters for various wavelengths). The light source and the sensor of reflected light are not on the same axis and it is therefore impossible to measure the moisture on the surface of small-size objects.
The technical solution disclosed in patent application WO 2006/118619 Al allows measuring of moisture on large surfaces, namely on a "continuous" paper on a machine for producing paper. The sensor comprises an optical head, in which infrared light travels along an optical fibre from a light source to a mirror, where it reflects onto the paper. The reflected infrared light therefrom is reflected again from the mirror and continues along another optical fibre to a photodiode. Since the incident light and the reflected light are not on the same axis, the head's configuration is not suitable for measuring the moisture on the surface of uneven objects especially of smaller sizes. Moreover, a Peltier cooler is needed to cool the light source.
The system for measuring moisture according to patent application No. EP 2028476 Al is used to measure moisture on the surface of large-size objects, for instance on a sheet of paper or various boards. The system measures the moisture content profile, for which both the reflection of infrared light and transmission of the infrared light through the paper are used. This measurement requires two optical heads and access from both sides of the paper. The system is therefore not suitable for measuring moisture on the surface of small-size uneven objects. A further disadvantage of the system is its high level of complexity, it uses mirrors and lenses that are subject to mechanical creeping and therefore cause imprecise measurements.
Solution to the Technical Problem
The described technical problem is solved by a sensor for measuring moisture on an uneven surface of the invention that has a special optical link between a light source and an object for simple, rapid and efficient measurement of moisture on the surface of objects having uneven geometry.
The sensor for measuring moisture is formed of a laser diode module comprising two laser diodes, a first photodiode, a second photodiode, a lock-in amplifier of the first photodiode, a lock-in amplifier of the second photodiode, a power regulator of the laser diode, an optical link, a module for data acquisition and a device for processing data, displaying measuring results and controlling the measurement method.
The laser diode module is formed of two laser diodes each radiating infrared light of a different wavelength: one radiates the light of the so-called measuring wavelength and another radiates the light of the so-called reference wavelength.
Said optical link is comprised of a main light guide and two legs in the form of light fibres. The main light guide that comprises light fibres optically links the light source and an object, the moisture of which is to be measured. One fibre of the main light guide, a first leg, bifurcates from the main light guide such that it optically links the light source and a light sensor - it transfers the light radiated by the light source. A second leg in the form of a light fibre joins the main light guide such that it optically links the light sensor and the object. This light fibre transfers the light reflected from the object. Each of the bifurcated light fibres guides the light to the light sensor: the first leg guides it to the first light sensor and the second leg guides it to the second light sensor. The light source in this case is two laser diodes and the light sensor is two photodiodes. The optical link not only allows measurement of the moisture on the surface of small- size objects having uneven geometry but also allows for compensation of instability of the light source due to the influence of temperature - it is a known fact that the optical power of laser light is rather temperature-dependent - and for compensation of the instability of light source due to mechanical influences. This is carried out in a way that the first leg transfers the light from the light source to the light sensor where the light is measured. The second leg guides the light reflected from the object to the light sensor. The instabilities or the noise measured in the light from the first leg (light source) are also measured in the light from the second leg (object). The instabilities thus get compensated.
The invention will be explained in more detail in the continuation by way of an embodiment and the enclosed drawings, representing in:
Figure 1 : a schematic view of a sensor; Figure 2: a schematic view of an optical link.
A sensor 1 for measuring moisture is formed of a laser diode module 2 comprising two laser diodes 3; a first photodiode 4; a second photodiode 5; a lock-in amplifier 6 of the first photodiode; a lock-in amplifier 7 of the second photodiode; a power regulator 8 of the laser diode; an optical link 11 that optically links the laser diode 3 with an object 14 to be measured, wherein a first leg 15 in the form of a light fibre is bifurcated from a main light guide 12, which guides the light from the laser diode 3 to the first photodiode 4, whereas a second leg 16 in the form of a light fibre connects to the main light guide 12 and guides the light reflected from the object 14 to the second photodiode 5; a module 9 for data acquisition; and a device 10 for processing data, displaying measurement results and controlling the method of measurement. Said optical link 11 is comprised of the main light guide 12 and two legs in the form of light fibres. The main light guide 12 which comprises light fibres 13 optically links the light source 3 and the object 14, the moisture of which is to be measured. One fibre of the main light guide 12, the first leg 15, is bifurcated from the main light guide 12, such that it optically links the light source 3 and the light sensor 4, and transfers the light radiated by the light source 3. The second leg 16 in the form of a light fibre joins the main light guide 12 in a way to optically link the light sensor 5 and the object 14. This light fibre transfers the light reflected from the object 14. Each of the bifurcated light fibres guides the light to the light sensor 4, 5, namely the first leg 15 to the first light sensor 4 and the second leg 16 to the second light sensor 5. The light source 3 in this case is the laser diodes and the light sensor 4, 5 is the two photodiodes.
The sensor can be adapted to be suitable for measuring moisture on the surface of objects that are preferably not from a polymeric material. It can also be adapted for the measurement of other substances, preferably liquids, on the surface of objects.

Claims

Claim
1. A sensor (1) for measuring moisture is formed of a laser diode module (2) comprising two laser diodes (3), a first photodiode (4), a second photodiode (5), a lock-in amplifier (6) of the first photodiode, a lock-in amplifier (7) of the second photodiode, a power regulator (8) of the laser diode, an optical link (11), a module (9) for data acquisition, and a device (10) for processing data, displaying measurement results and controlling the method of measurement, characterized in that the optical link (11) is provided with a first leg (15) that optically links the laser diode (3) and the first photodiode (4), wherewith it provides for compensation of instability of the laser diode (3) due to temperature and mechanical influences.
PCT/IB2015/058338 2014-10-30 2015-10-29 Sensor for measuring surface moisture on an uneven surface WO2016067228A1 (en)

Applications Claiming Priority (2)

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SIP-201400403 2014-10-30
SI201400403A SI24888A (en) 2014-10-30 2014-10-30 A sensor for measuring moisture on uneven surface

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107764368A (en) * 2016-08-17 2018-03-06 克利万工业-电子有限公司 Method and apparatus for monitoring the oil level in machine

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5005005A (en) * 1986-03-10 1991-04-02 Brossia Charles E Fiber optic probe system
US5178142A (en) * 1989-05-23 1993-01-12 Vivascan Corporation Electromagnetic method and apparatus to measure constituents of human or animal tissue
US20050228246A1 (en) * 2004-04-13 2005-10-13 Jangwoen Lee Method and apparatus for dynamically monitoring multiple in vivo tissue chromophores
WO2006118619A1 (en) 2005-04-28 2006-11-09 Honeywell International Inc. Sensor and methods for measuring select components in moving sheet products
EP2028476A1 (en) 2007-07-26 2009-02-25 Honeywell International Inc. System and method for measurement of degree of moisture stratification in a paper or board
US20110295541A1 (en) * 2008-04-25 2011-12-01 Bing Yu Systems and Methods for Performing Optical Spectroscopy Using a Self-Calibrating Fiber Optic Probe

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5005005A (en) * 1986-03-10 1991-04-02 Brossia Charles E Fiber optic probe system
US5178142A (en) * 1989-05-23 1993-01-12 Vivascan Corporation Electromagnetic method and apparatus to measure constituents of human or animal tissue
US20050228246A1 (en) * 2004-04-13 2005-10-13 Jangwoen Lee Method and apparatus for dynamically monitoring multiple in vivo tissue chromophores
WO2006118619A1 (en) 2005-04-28 2006-11-09 Honeywell International Inc. Sensor and methods for measuring select components in moving sheet products
EP2028476A1 (en) 2007-07-26 2009-02-25 Honeywell International Inc. System and method for measurement of degree of moisture stratification in a paper or board
US20110295541A1 (en) * 2008-04-25 2011-12-01 Bing Yu Systems and Methods for Performing Optical Spectroscopy Using a Self-Calibrating Fiber Optic Probe

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107764368A (en) * 2016-08-17 2018-03-06 克利万工业-电子有限公司 Method and apparatus for monitoring the oil level in machine
CN107764368B (en) * 2016-08-17 2020-08-07 克利万工业-电子有限公司 Method and device for monitoring oil level in machine

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