CA2017031A1 - Apparatus for the measurement of aerosols and dust or the like distributed in air - Google Patents
Apparatus for the measurement of aerosols and dust or the like distributed in airInfo
- Publication number
- CA2017031A1 CA2017031A1 CA002017031A CA2017031A CA2017031A1 CA 2017031 A1 CA2017031 A1 CA 2017031A1 CA 002017031 A CA002017031 A CA 002017031A CA 2017031 A CA2017031 A CA 2017031A CA 2017031 A1 CA2017031 A1 CA 2017031A1
- Authority
- CA
- Canada
- Prior art keywords
- light
- collector
- scattered light
- accordance
- scattered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000005259 measurement Methods 0.000 title claims abstract description 28
- 239000000428 dust Substances 0.000 title claims abstract description 19
- 239000000443 aerosol Substances 0.000 title claims abstract description 11
- 239000007850 fluorescent dye Substances 0.000 claims description 6
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 claims description 4
- 229920005372 Plexiglas® Polymers 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 claims description 3
- 230000003595 spectral effect Effects 0.000 claims description 3
- 239000004020 conductor Substances 0.000 claims 1
- 238000010276 construction Methods 0.000 claims 1
- 239000012141 concentrate Substances 0.000 abstract description 2
- 239000007787 solid Substances 0.000 description 11
- 239000002245 particle Substances 0.000 description 10
- 230000003287 optical effect Effects 0.000 description 7
- 238000001514 detection method Methods 0.000 description 5
- 239000000839 emulsion Substances 0.000 description 2
- 238000012625 in-situ measurement Methods 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000006194 liquid suspension Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005375 photometry Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
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
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
- G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/58—Photometry, e.g. photographic exposure meter using luminescence generated by light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/02—Investigating particle size or size distribution
- G01N15/0205—Investigating particle size or size distribution by optical means
-
- 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
- G01N2021/4704—Angular selective
- G01N2021/4707—Forward scatter; Low angle scatter
-
- 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
- G01N2021/4704—Angular selective
- G01N2021/4709—Backscatter
-
- 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
- G01N2021/4704—Angular selective
- G01N2021/4711—Multiangle measurement
- G01N2021/4716—Using a ring of sensors, or a combination of diaphragm and sensors; Annular sensor
-
- 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
- G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
- G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
- G01N21/538—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke for determining atmospheric attenuation and visibility
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
Abstract of Disclosure:
An apparatus is described for the measurement of aerosols and of dust distributed in the air in which the scattered light generated by the medium to be measured is detected by means of a transparent fluorescent scattered light collector (14). The light conducting characteristic of the scattered light collector (14) is exploited to concentrate the fluorescent light generated in the scattered light collector (14). The fluorescent light concentrated at the light exit region (26) of the collector is detected by means of photoreceivers (24).
(Fig- 1)
An apparatus is described for the measurement of aerosols and of dust distributed in the air in which the scattered light generated by the medium to be measured is detected by means of a transparent fluorescent scattered light collector (14). The light conducting characteristic of the scattered light collector (14) is exploited to concentrate the fluorescent light generated in the scattered light collector (14). The fluorescent light concentrated at the light exit region (26) of the collector is detected by means of photoreceivers (24).
(Fig- 1)
Description
201~31 APPARATUS FOR THE MEASUREM~NT OF AEROSOLS AND
DUST OR THE LIKE DISTRIBUTED IN AIR
The invention relates to an apparatus for the measurement of aerosols and dust or the like distributed in air, the apparatus comprising a light source for generating an extended elongate scattering volume by means of a primary beam directed into the medium to be measured, a collector for scattered light and also at least one photoreceiver connected after the collector for scattered light.
In an apparatus of this kind, which can for example serve for the investigation of ~iquid suspensions and emulsions, the scattered light emerging from the scattering volume is first concentrated and subsequently detected.
Scattered light photometry is a proven method for the measurement of aerosols and dust distributed in the air and also for the investigation of liquid suspensions and emulsions. The intensity of the scattered light and its distribution over the scattering angle are dependent on the particle size and particle concentration and can be used Eor their determination.
Particularly when the particle size is known an angular - -. ' ~ ' ~ .
: . :
. .
~ ~ -2~703~
resolution is not required for the scattered light measurement in order to determine the partide concentration.
On the contrary, in order to increase the signal/noise ratio in the range of scattering angles of interest it is necessary to detect as large a solid angle of the scattered light as possible. For this purpose a large detector surface or a corresponding optical concentrator is necessary.
The use of a large area detector such as for example a PIN
photodiode array or a photomultiplier (see US-PS 4 597 666) is however not only extremely costly but a large detector surface necessarily also leads to a large electrical capacity of the overall detector by which the noise of the detector is incr~ased.
Scattered light photometers are, on the other hand, known in which the scattered light is focussed by an image forming optical system onto the detector. In this way only a restricted solid angle can be detected even when using large area Fresnel lenses.
With the in-situ measurement of dust concentrations in room air, exhaust air or larger chimneys in particular, one is mainly concerned with extended scattering volumes. In such cases the use of an image forming optical system is no longer possible simply because of the restricted depth of focus. Finally, the detection of the full solid angle around a scattering volume can fundamentally not be realised by an image forming optical system.
The invention is based on the object of so further developing the apparatus of the initially named kind that the scattered light emerging from more extended scattering volumes can in particular also be measured with the simplest means over solid angle~ which are practically as large as ~017~31 desired.
The object is satisfied in accordance with the invention in that the collector for scattered light comprises transparent fluorescent material; and in that the photoreceiver is optically coupled to the light exit region of the scattered light collector which acts as a fluorescent light guide, with the particular scattering angles which are to be detected being determinable by a corresponding shape of the collector for scattered light.
Here several photoreceivers are advantageously provided and distributed uniformly over the light exit region of the scattered light collector.
As a result of the use of a fluorescent collector in accordance with the invention for the measurement of aerosols and dust or the like distributed in air, the collector can be matched without problem to the particular scattering angle geometry of interest. Even with more extended scattering volumes, such as can for example be present during the in-situ measurement of dust concentrations in room air, exhaust air or larger chimneys the scattered light can be detected with the collector over a solid angle which is practically as large as desired. With a larger solid angle of this kind the signal/noise ratio of the scattered light detection increases so that on the whole a more precise measurement is possible.
-The invention is accordingly in particular based on theconcept, for the measurement of aerosols or of dust distributed in the air, of simultaneously using transparent fluorescent elements as collectors for the scattered light which is to be detected and as optical concentrators, with the invention exploiting the characteristic of the 2~1~7~31 correspondingly shaped transparent fluorescent elements that they concentrate at least a large part of the fluorescenk light to a remaining light exit zone in the manner of a light guide, practically independently of the particular shape.
Finally, the deposition of dust ont.o the transparent fluorescent collectors is unproblematic in contrast to dust deposits on the lenses of an image forming optical system since light incident on the dust grains is scattered on into the collector at least to a large degree. The directional independency of the collectors accordingly contributes in particular to ensuring a measurement accuracy and sensitiYity which is as high as possible, even when dust deposits are present on the collector.
The mass concentration of the scattering medium and/or the range of visibility present in the scattering medium can for example be determined from the measured intensity of the scattered light. Furthermore, it is also possible to determine the size of the particles present in the scattering medium from the dependence of the measured intensity of the scattered light on the wavelength of the light.
While it is preferably only the intensity of the forward scattering which is measured, in particular for the determination of medium mass concentrations it can be expedient, in particular for the determination of lower mass concentrations to measure the scattered light intensity over at least substantially the entire solid angle.
A part of the light exit region of the scattered light collector which acts as a fluorescent light guide can be made specularly reflecting or provided with reflector 2~03t surfaces, with the photoreceivers in this case being optically coupled to the remaining non-specularly reflecting part of the light exit region.
The mirrored or reflector surfaces not only prevent possible light loss but also reduce the light exit area at which photoelements are to be provided. The number of the photoelements that are required can thus be kept extremely small.
If for example it is only desired to detect the forward or backward scattering then it is expedient to design the scattered light collector in plate-like manner and to arrange the photoreceiver or receivers at the edge of the plate.
For the detection of the forward or backward scattering it is of advantage when the plate-like scattered light collector is arranged at least substantially perpendicular to a preferably narrow light beam emerging from the light source. In this arrangement the scattered light collector can have a central opening through which the narrow light beam originating from the light source passes.
In another variant it is however also possible to guide the primary light originating from the light source sideways past the scattered light collector. If several light sources are provided then the scattered light collector is praferably arranged between the preferably mutually parallel light beams generated by the light sources. An arrangement of this kind can for example be used for the measurement of the back radiation.
For the determination of higher mass concentrations in particular it is preferably only the intensity of this back 2~17~31 scattering which is measured. For example, with an arrangement of one or several light sources (~or example light emitting diodes) at the center of a plate-like fluorescent collector or around the latter with radiation into tha scattering medium the collector will collect the scattered light radiated back by the scattering medium.
An extremely simple arrangement for detecting the forward scattering is obtained if the scattered light collector has a spacing from the light source and includes a collector surface which faces the light source and which is illuminated by the forwardly scattered light.
A further variant is characterised in that the scattered light collector is arranged in the region of the light source and has a collector surface which detects the back scattering.
Those collector surfaces which are not to deliver a contribution to the measurement result can for example be made specularly reflecting at the outside. Furthermore, when using plate-like scattered light collectors it is mainly expedient to make these of circular shape.
In particular for the determination of the range of visibility by the measurement of the light scattered in the atmosphere it is necessary to measure the scattered light intensity either so far as possible over the entire solid angle or to detect a fraction proportional to this. ~ith unpolarised incident light in particular the scattered light intensity is expediently measured with this arrangement over at least substantially the entire range of scattered angles from 0 to 180 over a constant azimutual aperture angle. A
geometry of this kind can be realised with an elongate scattering volume in the incident light beam (for example 2~17~31 laser beam) for example by a tube or by a half tube around the primary beam or by a narrow collector strip parallel to the primary beam.
If it is desired to measure not only the forward scattering and the backward scattering but rather also the scattering over as large a solid angle as possible, or to detect a fraction of the scattered light proportional to this provision is accordingly advantageously made for the scattered light collector to be tubular or to have the shape of a tubular section, and for the photoreceivers to be provided at the ends of the tube, or at least at one tube end and/or at one of the two elongate side edges of the tubular section. If photoreceivers are only provided at one tube end then the other tube end is again preferably provided with reflector surfaces in order to avoid possible light loss. Reflector surfaces can also be correspondingly provided at the elongate edges.
When using a tubular scattered light collector or a scattered light collector having the shape of the section of the tube the narrow light beam generated by the light source is preferably directed along the tube axis.
The scattered light collectors are preferably manufactured from fluorescent plexiglass or from other organic or inorganic glasses doped with fluorescent dye. By way of example, with a collector plate consisting of plexiglass, approximately 74~ of the fluorescent light does not emerge from the plate surface as a result of total reflection. On the contrary this proportion of the light passes as in a light guide to the edges of this plate.
Relatively high degrees of efficiency can in particular be achieved if the light source generates monochromatic light 2~17031 and if the fluorescent dye of the scattered light collector is matched to the wavelength of the monochromatic light. The wavelength of the fluorescent light: can preferably also be matched to the maximum spectral sensitivity of the photoreceivers.
In accordance with a further embodiment several scattered light collectors, in particular scattered light collectors arranged above one another, are provided with different absorption wavelengths, with at least one light source which transmits polychromatic light being associated with these transparent fluorescent scattered light collectors. The scattered light can in this case be simultaneously measured at several wavelengths. Conclusions can then in particular be drawn concerning the particle size in the scattering medium from the dependency of the intensity of the scattered light on the wavelength.
Further advantageous variants of the invention are set forth in the subordinate claims.
The invention will now be described in the following in more detail with reference to examples and to the drawing in which are shown:
Fig. 1 an apparatus for the measurement of the intensit~ of the forward scattering by means of a plate-like, transparent, fluorescent collector for scattered light, Fig. 2 an apparatus for the measurement of the scattered light intensity over approximately the entire solid angle by means of a transparent fluorescent tube, Fig. 3 a measurement apparatus comparable with the 20~7~31 apparatus of Fig. 2 in which however a transparent fluorescent half tube is used to detect the scattered light, and Fig. 4 an apparatus for measuring the intensity of the back scattering, with a plate-like transparent fluorescent collector agai;n being provided for detection of the scattered light of interest.
The measurement arrangement shown in Figs. 1 to 4 serves for the measurement of the intensity of the scattered light which emerges from a scattering volume in which a scattering medium 22 is illuminated by light by means of light source 12 and 12' and 12' respectively.
In the arrangements of Figs. 1 to 3 the scattering volume is in each case generated by a narrow light beam 30 which is transmitted by the light source and directed into the scattering medium 22. In the measurement arrangement shown in Fig. 4 two light sources 12' and 12" are provided to generate two narrow light beams 30.
The scattered light is in each case detected by means of a transparent fluorescent collector 14, 16, 18 or 20. Here a transparent fluorescent collector acting as a fluorescent light guide is in each case provided for the concentration of the fluorescent light generated in the collector 14, 16, 18 or 20.
The scattered light concentrators or collectors 14, 16, 18 or 20 that are used can in particular be manufactured from fluorescent plexiglass, or from another organic or inorganic glass doped with a fluorescent dye.
The scattered light collectors 14-20 which detect the ~017~31 relevant scattered light component simultaneously operate as optical concentrators as a result of the light conducting characteristics for the fluorescent light. Only a small part of the fluorescent light can namely emerge from the collector surface as a result of the total internal reflection. This small part of the light large passes to restricted light exit regions 26, as in a light guide, where the concentrated fluorescent light is finally detected by means of photoreceivers 24.
The photoelements 24 can for example be PIN photodiodes which are optically coupled to the light exit regions 26 of the fluorescent light guides or scattered light collectors 14, 16, 18 or 20 for the detection of the fluorescent light.
Reflector surfaces are provided at the portions of the light exit regions not occupied with photoreceivers in order to avoid possible light loss. In the measurement arrangement of Fig. 1 which is provided for the measurement of the mass concentration of an aerosol only one light source 12 is provided to generate a narrow light beam 30 which is directed into the scattering medium 22. The scattered light collector 14 of transparent fluorescent material is arranged at a clear distance from the light source 12 and is formed in the present case as a large area circular plate. The plate-like scattered light collector 14 stands perpendicular to the narrow incident light beam 30 which as the primary beam generates an extended elongate scattering volume.
The plate-like scattered light collector 14 has a central opening 28 through which this narrow light ~eam 30 originating from the light source 12 passes.
The surface of the scattered light collector 14 facing the light source 12 detects the forward scattering emerging from the scattered volums. The oppositely disposed surface of the 2~1~031 scattered light collector 14 can be treated in such a way that any back scattering which eventually occurs has no effect on the generation of the fluorescent light.
The photoreceivers 24 are uniformly distributed over the edge of the plate~ e scattered light collector 14. In order to avoid a possible light loss the regions of the plate edge between the photoreceivers can be provided with reflector surfaces. Through appropriate dimensioning of a plate-like scattered light collector 14 of this kind it can be arranged that the scattered light captured within a certain size range of the scattered particles (ca. 1 to 100 times the wavelength) is independent from the particle size and proportional to the total mass of the scattering particles.
The measurement arrangement of Fig. 2 is for example suitable for the determination of extremely low aerosol or dust concentrations where the largest possible part of the scattered light is to be detected.
~or this purpose the transparent, fluorescent, collector 16 for scattered light is formed as a tube which surrounds the narrow light beam 30 coming from the light source 12. The primary beam or the narrow light beam 30 extends along the tube axis through the scattering medium 22.
The photoreceivers 24 are optically coupled to the edges of the two tube ends (to the end faces of the tube) and are in turn uniformly distributed over the relevant edge. It is however also basically possible to provide such photoreceivers 24 at only one tube end and the edge not occupied with photoreceivers can again be provided with reflector surfaces. Moreover, the region between two photoreceivers 24 can also again be mirrored or provided 2~703~
with reflector surfaces.
In this measurement arrangement the largest part of the light scattered by the particles in the tube is absorbed by the tube walls and is passed on in large part as fluorescent light to the tube ends as a conse~lence of the light conducting characteristics of the t:ube. With constant particle size distribution the intensity of the ~luorescent light emerging at the edges of the tube ends is proportional to the dust or aerosol concentration in the tube.
Fig. 3 shows a measurement arrangement comparable to the arrangement of Fig. 2 in which however the transparent fluorescent scattered light collector 18 is simply formed by a half tube. The narrow light beam generat~d by the light source 12 again extends along the tube axis through the scattering medium 22. Photoelements 24 are again optically coupled to the edge (end face) of the tube ends, i.e. to the light exit rPgion 26 of the scattered light collector which acts as the fluorescent light guide. As the longitudinal side edges also form a light exit region 26 reflector surfaces are provided there to avoid possible light loss. It is however also possible to arrange photoreceivers at these longitudinal edges.
This arrangement is in particular suitable for the determination of the range of visibility in the atmosphere since for this purpose the scattered light intensity must either be detected over the entire solid angle as far as possible or a fraction proportional to this must be detected. With non-polarised incident light this signifies that the scattered light is to be detected with a constant azimutual opening angle over the entire range of scattering angles from 0 to 180. A geometry of this kind can however be realised with an elongate scattering volume in the - 13 - 2~7~1 incident li~ht ~eam (for example laser ~eam) by a tube or a half tube around the primary beam or by a narrow detector strip parallel to the primary beam.
The measurement arrangement shown in Fig. 4 includes two light sources 121, 12" which generates two at least substantially mutually parallel narrow light beams 30. A
large area circular plate is again provided as a transparent fluorescent scattered light collector 20 as in the case o~
the arrangement of Fig. 1.
The scattered light collector 20 is however arranged directly in the vicinity of the light sources 12' and 12"
and between the two narrow light beams 30. This measurement arrangement serves to detect the back scattering of the medium 22 which, is in particular with extremely high dust concentrations, represents a suitable measure for the dust concentration. The back scattering is detected in the present case by the surface of the plate-like scattered light collector 20 which faces away from the light sources 12', 12". The surface of the scattered light collector which faces the light sources can in turn be dealt with in such a way that the forward scattering has no influence on the genaration of the fluorescent light. Several photoelements 24 are again uniformly distributed over the edge or side surface of the circular plate, i.e. the light exit region 26 of the plate~ e, circular collector 20 for scattered light, and the concentrated fluorescent light is detected via these photoelements.
In place of the illustrated outer light sources 12' and 12"
one can also provide one or more light sources in the central region of the disk-like scattered light collector 20.
20~703~
An advantageous use of the measurement arrangement of the invention is in particular always possible where priceworthy large area receivers are re~uired with simultaneously large apertures.
It is not only important that the fluorescent dye can be adapted to achieve a maximum absorption of the measurement wavQlength but rather also that the wavelength of the fluorescent light can be matched to the maximum spectral sensitivity of the particular photoreceiver (for example silicon).
The following fields of application are in particular conceivable: dust detectors in exhaust gases, dust monitoring at the workplace or in the exhaust air from halls, air conditionin~ systems, visibility measuring apparatus etc. Here the shape of the transparent fluorescent scattered light collector can in each case be matched without problem to the required scattering angle geometry.
DUST OR THE LIKE DISTRIBUTED IN AIR
The invention relates to an apparatus for the measurement of aerosols and dust or the like distributed in air, the apparatus comprising a light source for generating an extended elongate scattering volume by means of a primary beam directed into the medium to be measured, a collector for scattered light and also at least one photoreceiver connected after the collector for scattered light.
In an apparatus of this kind, which can for example serve for the investigation of ~iquid suspensions and emulsions, the scattered light emerging from the scattering volume is first concentrated and subsequently detected.
Scattered light photometry is a proven method for the measurement of aerosols and dust distributed in the air and also for the investigation of liquid suspensions and emulsions. The intensity of the scattered light and its distribution over the scattering angle are dependent on the particle size and particle concentration and can be used Eor their determination.
Particularly when the particle size is known an angular - -. ' ~ ' ~ .
: . :
. .
~ ~ -2~703~
resolution is not required for the scattered light measurement in order to determine the partide concentration.
On the contrary, in order to increase the signal/noise ratio in the range of scattering angles of interest it is necessary to detect as large a solid angle of the scattered light as possible. For this purpose a large detector surface or a corresponding optical concentrator is necessary.
The use of a large area detector such as for example a PIN
photodiode array or a photomultiplier (see US-PS 4 597 666) is however not only extremely costly but a large detector surface necessarily also leads to a large electrical capacity of the overall detector by which the noise of the detector is incr~ased.
Scattered light photometers are, on the other hand, known in which the scattered light is focussed by an image forming optical system onto the detector. In this way only a restricted solid angle can be detected even when using large area Fresnel lenses.
With the in-situ measurement of dust concentrations in room air, exhaust air or larger chimneys in particular, one is mainly concerned with extended scattering volumes. In such cases the use of an image forming optical system is no longer possible simply because of the restricted depth of focus. Finally, the detection of the full solid angle around a scattering volume can fundamentally not be realised by an image forming optical system.
The invention is based on the object of so further developing the apparatus of the initially named kind that the scattered light emerging from more extended scattering volumes can in particular also be measured with the simplest means over solid angle~ which are practically as large as ~017~31 desired.
The object is satisfied in accordance with the invention in that the collector for scattered light comprises transparent fluorescent material; and in that the photoreceiver is optically coupled to the light exit region of the scattered light collector which acts as a fluorescent light guide, with the particular scattering angles which are to be detected being determinable by a corresponding shape of the collector for scattered light.
Here several photoreceivers are advantageously provided and distributed uniformly over the light exit region of the scattered light collector.
As a result of the use of a fluorescent collector in accordance with the invention for the measurement of aerosols and dust or the like distributed in air, the collector can be matched without problem to the particular scattering angle geometry of interest. Even with more extended scattering volumes, such as can for example be present during the in-situ measurement of dust concentrations in room air, exhaust air or larger chimneys the scattered light can be detected with the collector over a solid angle which is practically as large as desired. With a larger solid angle of this kind the signal/noise ratio of the scattered light detection increases so that on the whole a more precise measurement is possible.
-The invention is accordingly in particular based on theconcept, for the measurement of aerosols or of dust distributed in the air, of simultaneously using transparent fluorescent elements as collectors for the scattered light which is to be detected and as optical concentrators, with the invention exploiting the characteristic of the 2~1~7~31 correspondingly shaped transparent fluorescent elements that they concentrate at least a large part of the fluorescenk light to a remaining light exit zone in the manner of a light guide, practically independently of the particular shape.
Finally, the deposition of dust ont.o the transparent fluorescent collectors is unproblematic in contrast to dust deposits on the lenses of an image forming optical system since light incident on the dust grains is scattered on into the collector at least to a large degree. The directional independency of the collectors accordingly contributes in particular to ensuring a measurement accuracy and sensitiYity which is as high as possible, even when dust deposits are present on the collector.
The mass concentration of the scattering medium and/or the range of visibility present in the scattering medium can for example be determined from the measured intensity of the scattered light. Furthermore, it is also possible to determine the size of the particles present in the scattering medium from the dependence of the measured intensity of the scattered light on the wavelength of the light.
While it is preferably only the intensity of the forward scattering which is measured, in particular for the determination of medium mass concentrations it can be expedient, in particular for the determination of lower mass concentrations to measure the scattered light intensity over at least substantially the entire solid angle.
A part of the light exit region of the scattered light collector which acts as a fluorescent light guide can be made specularly reflecting or provided with reflector 2~03t surfaces, with the photoreceivers in this case being optically coupled to the remaining non-specularly reflecting part of the light exit region.
The mirrored or reflector surfaces not only prevent possible light loss but also reduce the light exit area at which photoelements are to be provided. The number of the photoelements that are required can thus be kept extremely small.
If for example it is only desired to detect the forward or backward scattering then it is expedient to design the scattered light collector in plate-like manner and to arrange the photoreceiver or receivers at the edge of the plate.
For the detection of the forward or backward scattering it is of advantage when the plate-like scattered light collector is arranged at least substantially perpendicular to a preferably narrow light beam emerging from the light source. In this arrangement the scattered light collector can have a central opening through which the narrow light beam originating from the light source passes.
In another variant it is however also possible to guide the primary light originating from the light source sideways past the scattered light collector. If several light sources are provided then the scattered light collector is praferably arranged between the preferably mutually parallel light beams generated by the light sources. An arrangement of this kind can for example be used for the measurement of the back radiation.
For the determination of higher mass concentrations in particular it is preferably only the intensity of this back 2~17~31 scattering which is measured. For example, with an arrangement of one or several light sources (~or example light emitting diodes) at the center of a plate-like fluorescent collector or around the latter with radiation into tha scattering medium the collector will collect the scattered light radiated back by the scattering medium.
An extremely simple arrangement for detecting the forward scattering is obtained if the scattered light collector has a spacing from the light source and includes a collector surface which faces the light source and which is illuminated by the forwardly scattered light.
A further variant is characterised in that the scattered light collector is arranged in the region of the light source and has a collector surface which detects the back scattering.
Those collector surfaces which are not to deliver a contribution to the measurement result can for example be made specularly reflecting at the outside. Furthermore, when using plate-like scattered light collectors it is mainly expedient to make these of circular shape.
In particular for the determination of the range of visibility by the measurement of the light scattered in the atmosphere it is necessary to measure the scattered light intensity either so far as possible over the entire solid angle or to detect a fraction proportional to this. ~ith unpolarised incident light in particular the scattered light intensity is expediently measured with this arrangement over at least substantially the entire range of scattered angles from 0 to 180 over a constant azimutual aperture angle. A
geometry of this kind can be realised with an elongate scattering volume in the incident light beam (for example 2~17~31 laser beam) for example by a tube or by a half tube around the primary beam or by a narrow collector strip parallel to the primary beam.
If it is desired to measure not only the forward scattering and the backward scattering but rather also the scattering over as large a solid angle as possible, or to detect a fraction of the scattered light proportional to this provision is accordingly advantageously made for the scattered light collector to be tubular or to have the shape of a tubular section, and for the photoreceivers to be provided at the ends of the tube, or at least at one tube end and/or at one of the two elongate side edges of the tubular section. If photoreceivers are only provided at one tube end then the other tube end is again preferably provided with reflector surfaces in order to avoid possible light loss. Reflector surfaces can also be correspondingly provided at the elongate edges.
When using a tubular scattered light collector or a scattered light collector having the shape of the section of the tube the narrow light beam generated by the light source is preferably directed along the tube axis.
The scattered light collectors are preferably manufactured from fluorescent plexiglass or from other organic or inorganic glasses doped with fluorescent dye. By way of example, with a collector plate consisting of plexiglass, approximately 74~ of the fluorescent light does not emerge from the plate surface as a result of total reflection. On the contrary this proportion of the light passes as in a light guide to the edges of this plate.
Relatively high degrees of efficiency can in particular be achieved if the light source generates monochromatic light 2~17031 and if the fluorescent dye of the scattered light collector is matched to the wavelength of the monochromatic light. The wavelength of the fluorescent light: can preferably also be matched to the maximum spectral sensitivity of the photoreceivers.
In accordance with a further embodiment several scattered light collectors, in particular scattered light collectors arranged above one another, are provided with different absorption wavelengths, with at least one light source which transmits polychromatic light being associated with these transparent fluorescent scattered light collectors. The scattered light can in this case be simultaneously measured at several wavelengths. Conclusions can then in particular be drawn concerning the particle size in the scattering medium from the dependency of the intensity of the scattered light on the wavelength.
Further advantageous variants of the invention are set forth in the subordinate claims.
The invention will now be described in the following in more detail with reference to examples and to the drawing in which are shown:
Fig. 1 an apparatus for the measurement of the intensit~ of the forward scattering by means of a plate-like, transparent, fluorescent collector for scattered light, Fig. 2 an apparatus for the measurement of the scattered light intensity over approximately the entire solid angle by means of a transparent fluorescent tube, Fig. 3 a measurement apparatus comparable with the 20~7~31 apparatus of Fig. 2 in which however a transparent fluorescent half tube is used to detect the scattered light, and Fig. 4 an apparatus for measuring the intensity of the back scattering, with a plate-like transparent fluorescent collector agai;n being provided for detection of the scattered light of interest.
The measurement arrangement shown in Figs. 1 to 4 serves for the measurement of the intensity of the scattered light which emerges from a scattering volume in which a scattering medium 22 is illuminated by light by means of light source 12 and 12' and 12' respectively.
In the arrangements of Figs. 1 to 3 the scattering volume is in each case generated by a narrow light beam 30 which is transmitted by the light source and directed into the scattering medium 22. In the measurement arrangement shown in Fig. 4 two light sources 12' and 12" are provided to generate two narrow light beams 30.
The scattered light is in each case detected by means of a transparent fluorescent collector 14, 16, 18 or 20. Here a transparent fluorescent collector acting as a fluorescent light guide is in each case provided for the concentration of the fluorescent light generated in the collector 14, 16, 18 or 20.
The scattered light concentrators or collectors 14, 16, 18 or 20 that are used can in particular be manufactured from fluorescent plexiglass, or from another organic or inorganic glass doped with a fluorescent dye.
The scattered light collectors 14-20 which detect the ~017~31 relevant scattered light component simultaneously operate as optical concentrators as a result of the light conducting characteristics for the fluorescent light. Only a small part of the fluorescent light can namely emerge from the collector surface as a result of the total internal reflection. This small part of the light large passes to restricted light exit regions 26, as in a light guide, where the concentrated fluorescent light is finally detected by means of photoreceivers 24.
The photoelements 24 can for example be PIN photodiodes which are optically coupled to the light exit regions 26 of the fluorescent light guides or scattered light collectors 14, 16, 18 or 20 for the detection of the fluorescent light.
Reflector surfaces are provided at the portions of the light exit regions not occupied with photoreceivers in order to avoid possible light loss. In the measurement arrangement of Fig. 1 which is provided for the measurement of the mass concentration of an aerosol only one light source 12 is provided to generate a narrow light beam 30 which is directed into the scattering medium 22. The scattered light collector 14 of transparent fluorescent material is arranged at a clear distance from the light source 12 and is formed in the present case as a large area circular plate. The plate-like scattered light collector 14 stands perpendicular to the narrow incident light beam 30 which as the primary beam generates an extended elongate scattering volume.
The plate-like scattered light collector 14 has a central opening 28 through which this narrow light ~eam 30 originating from the light source 12 passes.
The surface of the scattered light collector 14 facing the light source 12 detects the forward scattering emerging from the scattered volums. The oppositely disposed surface of the 2~1~031 scattered light collector 14 can be treated in such a way that any back scattering which eventually occurs has no effect on the generation of the fluorescent light.
The photoreceivers 24 are uniformly distributed over the edge of the plate~ e scattered light collector 14. In order to avoid a possible light loss the regions of the plate edge between the photoreceivers can be provided with reflector surfaces. Through appropriate dimensioning of a plate-like scattered light collector 14 of this kind it can be arranged that the scattered light captured within a certain size range of the scattered particles (ca. 1 to 100 times the wavelength) is independent from the particle size and proportional to the total mass of the scattering particles.
The measurement arrangement of Fig. 2 is for example suitable for the determination of extremely low aerosol or dust concentrations where the largest possible part of the scattered light is to be detected.
~or this purpose the transparent, fluorescent, collector 16 for scattered light is formed as a tube which surrounds the narrow light beam 30 coming from the light source 12. The primary beam or the narrow light beam 30 extends along the tube axis through the scattering medium 22.
The photoreceivers 24 are optically coupled to the edges of the two tube ends (to the end faces of the tube) and are in turn uniformly distributed over the relevant edge. It is however also basically possible to provide such photoreceivers 24 at only one tube end and the edge not occupied with photoreceivers can again be provided with reflector surfaces. Moreover, the region between two photoreceivers 24 can also again be mirrored or provided 2~703~
with reflector surfaces.
In this measurement arrangement the largest part of the light scattered by the particles in the tube is absorbed by the tube walls and is passed on in large part as fluorescent light to the tube ends as a conse~lence of the light conducting characteristics of the t:ube. With constant particle size distribution the intensity of the ~luorescent light emerging at the edges of the tube ends is proportional to the dust or aerosol concentration in the tube.
Fig. 3 shows a measurement arrangement comparable to the arrangement of Fig. 2 in which however the transparent fluorescent scattered light collector 18 is simply formed by a half tube. The narrow light beam generat~d by the light source 12 again extends along the tube axis through the scattering medium 22. Photoelements 24 are again optically coupled to the edge (end face) of the tube ends, i.e. to the light exit rPgion 26 of the scattered light collector which acts as the fluorescent light guide. As the longitudinal side edges also form a light exit region 26 reflector surfaces are provided there to avoid possible light loss. It is however also possible to arrange photoreceivers at these longitudinal edges.
This arrangement is in particular suitable for the determination of the range of visibility in the atmosphere since for this purpose the scattered light intensity must either be detected over the entire solid angle as far as possible or a fraction proportional to this must be detected. With non-polarised incident light this signifies that the scattered light is to be detected with a constant azimutual opening angle over the entire range of scattering angles from 0 to 180. A geometry of this kind can however be realised with an elongate scattering volume in the - 13 - 2~7~1 incident li~ht ~eam (for example laser ~eam) by a tube or a half tube around the primary beam or by a narrow detector strip parallel to the primary beam.
The measurement arrangement shown in Fig. 4 includes two light sources 121, 12" which generates two at least substantially mutually parallel narrow light beams 30. A
large area circular plate is again provided as a transparent fluorescent scattered light collector 20 as in the case o~
the arrangement of Fig. 1.
The scattered light collector 20 is however arranged directly in the vicinity of the light sources 12' and 12"
and between the two narrow light beams 30. This measurement arrangement serves to detect the back scattering of the medium 22 which, is in particular with extremely high dust concentrations, represents a suitable measure for the dust concentration. The back scattering is detected in the present case by the surface of the plate-like scattered light collector 20 which faces away from the light sources 12', 12". The surface of the scattered light collector which faces the light sources can in turn be dealt with in such a way that the forward scattering has no influence on the genaration of the fluorescent light. Several photoelements 24 are again uniformly distributed over the edge or side surface of the circular plate, i.e. the light exit region 26 of the plate~ e, circular collector 20 for scattered light, and the concentrated fluorescent light is detected via these photoelements.
In place of the illustrated outer light sources 12' and 12"
one can also provide one or more light sources in the central region of the disk-like scattered light collector 20.
20~703~
An advantageous use of the measurement arrangement of the invention is in particular always possible where priceworthy large area receivers are re~uired with simultaneously large apertures.
It is not only important that the fluorescent dye can be adapted to achieve a maximum absorption of the measurement wavQlength but rather also that the wavelength of the fluorescent light can be matched to the maximum spectral sensitivity of the particular photoreceiver (for example silicon).
The following fields of application are in particular conceivable: dust detectors in exhaust gases, dust monitoring at the workplace or in the exhaust air from halls, air conditionin~ systems, visibility measuring apparatus etc. Here the shape of the transparent fluorescent scattered light collector can in each case be matched without problem to the required scattering angle geometry.
Claims (15)
1. Apparatus for the measurement of aerosols and dust or the like distributed in air, the apparatus comprising a light source (12, 12', 12") for generating an extended elongate scattering volume by means of a primary beam directed into the medium (22) to be measured, a collector (14-20) for scattered light and also at least one photoreceiver (24) connected after the collector for scattered light, characterised in that the collector (14-20) for scattered light comprises transparent fluorescent material; and in that the photoreceiver (24) is optically coupled to the light exit region (26) of the scattered light collector which acts as a fluorescent light guide, with the particular scattering angles which are to be detected being determinable by a corresponding shape of the collector (14-20) for scattered light.
2. Apparatus in accordance with claim 1, characterised in that several photoreceivers (24) are provided which are uniformly distributed over the light exit region (26) of the scattered light collector (14-20).
3. Apparatus in accordance with claim 1, characterised in that the light exit region (26) of the scattered light collector (14-20) which acts as the fluorescent light conductor is made specularly reflecting in part; and in that the photoreceiver or receivers (24) are optically coupled onto the remaining non-specularly reflecting part of the light exit region (26).
4. Apparatus in accordance with claim 1, characterised in that the scattered light collector (14, 20) is of plate-like construction; in that the photoreceiver or receivers (24) are arranged at the edge of the plate and in that the plate-like scattered light collector (14, 20) is arranged at least substantially perpendicular to a narrow light beam (30) emerging from the light source (12, 12', 12").
5. Apparatus in accordance with claim 4, characterised in that the plate-like scattered light collector (14) has a central opening (28) through which the narrow light beam (30) originating from the light source (12) passes.
6. Apparatus in accordance with claim 1, characterised in that several light sources (12', 12") are provided; and in that the scattered light collector (20) is arranged between the preferably mutually parallel light beams (30) generated from the light sources.
7. Apparatus in accordance with claim 1, characterised in that the scattered light collector (14) has a distance from the light source (12) and includes a collector surface which faces the light source to detect the forward scattering.
8. Apparatus in accordance with claim 1, characterised in that the scattered light collector (20) is arranged in the region of the light source and has a collector surface which detects the back scattering.
9. Apparatus in accordance with claim 1, characterised in that the scattered light collector (16, 18) is tubular or has the shape of a tubular section; in that the photoreceivers (24) are arranged at an end of the tube or at least at one tube end and/or at one of the two longitudinal side edges of the tubular section; and in that the narrow light beam (30) generated by the light source (12) is preferably directed along the tube axis.
10. Apparatus in accordance with claim 1, characterised in that the scattered light collector (14-20) consists of fluorescent plexiglass.
11. Apparatus in accordance with claim 1, characterised in that the scattered light collector (14-20) consists of organic or inorganic glass doped with a fluorescent dye.
12. Apparatus in accordance with claim 1, characterised in that the light source (12, 12', 12") generates monochromatic light and the fluorescent dye of the scattered light collector (14-20) is matched to the wavelength of the monochromatic light.
13. Apparatus in accordance with claim 1, characterised in that several scattered light collectors, in particular scattered light collectors arranged above one another, are provided with different absorption wavelengths; and in that a light source which transmits polychromatic light is associated with the scattered light collectors.
14. Apparatus in accordance with claim 1, characterised in that the photoreceivers (24) are PIN photodiodes.
15. Apparatus in accordance with claim 1, characterised in that the wavelength of the fluorescent light is matched to the maximum spectral sensitivity of the photoreceivers (24).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3917571.5 | 1989-05-30 | ||
| DE3917571A DE3917571A1 (en) | 1989-05-30 | 1989-05-30 | METHOD FOR MEASURING THE INTENSITY OF SPARKLIGHT AND MEASURING DEVICE FOR CARRYING OUT THE METHOD |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2017031A1 true CA2017031A1 (en) | 1990-11-30 |
Family
ID=6381681
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002017031A Abandoned CA2017031A1 (en) | 1989-05-30 | 1990-05-17 | Apparatus for the measurement of aerosols and dust or the like distributed in air |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0402633B1 (en) |
| JP (1) | JPH03214038A (en) |
| CA (1) | CA2017031A1 (en) |
| DD (1) | DD294794A5 (en) |
| DE (2) | DE3917571A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010058102A1 (en) | 2008-11-18 | 2010-05-27 | Centre National De La Recherche Scientifique - Cnrs - | Method and system for analysing solid particles in a medium |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5173434A (en) * | 1990-11-05 | 1992-12-22 | Baxter Diagnostics Inc. | Measurement of color reactions by monitoring a change of fluorescence |
| JP5112312B2 (en) * | 2005-07-15 | 2013-01-09 | バイオヴィジラント システムズ インコーポレイテッド | Pathogen and particulate detection system and detection method |
| DE102005040351B4 (en) * | 2005-08-25 | 2007-05-24 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Radiation modules, arrangements containing them and methods for detection, control and monitoring |
| CN112577882A (en) * | 2020-12-07 | 2021-03-30 | 广西电网有限责任公司电力科学研究院 | Method and device for detecting metal particles in GIS disconnecting link air chamber |
| CN112577867A (en) * | 2020-12-08 | 2021-03-30 | 广西电网有限责任公司电力科学研究院 | Method and device for detecting suspended particles in gas chamber of GIS (gas insulated switchgear) |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3323889A (en) * | 1963-04-16 | 1967-06-06 | Owens Illinois Inc | Method for increasing scratch resistance of a glass surface with a pyrolyzing treatment and a coating of an olefin polymer |
| DE1211421C2 (en) * | 1963-12-12 | 1973-11-15 | DEVICE FOR SCANNING GOOD THROUGH GOOD | |
| US3835315A (en) * | 1972-12-06 | 1974-09-10 | Us Commerce | System for determining parameters of a particle by radiant energy scattering techniques |
| US4017186A (en) * | 1975-03-05 | 1977-04-12 | Environmental Systems Corporation | Electro-optical method and system for in situ measurements of particulate mass density |
| US4262206A (en) * | 1980-01-11 | 1981-04-14 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Fluorescent radiation converter |
| US4371897A (en) * | 1980-09-02 | 1983-02-01 | Xerox Corporation | Fluorescent activated, spatially quantitative light detector |
| DE3119570A1 (en) * | 1981-05-16 | 1982-12-02 | Fa. Carl Zeiss, 7920 Heidenheim | FLUORESCENT MATERIAL CONTAINING RADIATION SENSOR |
| DE3249927C2 (en) * | 1982-09-01 | 1988-07-21 | Siemens Ag | Arrangement for determining the intensity of the light emission from an infrared diode |
| DE3404711A1 (en) * | 1984-02-10 | 1985-08-14 | Fa. Carl Zeiss, 7920 Heidenheim | Radiation sensor for microscopic photometry |
| US4597666A (en) * | 1984-04-18 | 1986-07-01 | The United States Of America As Represented By The Secretary Of The Navy | Apparatus for determining the liquid water content of a gas |
| FR2587023A1 (en) * | 1985-09-06 | 1987-03-13 | Rhone Poulenc Spec Chim | Luminescent vitreous material, its preparation and its use for the luminescent collection of solar energy |
| DE3538472A1 (en) * | 1985-10-29 | 1987-04-30 | Gw Elektronik Gmbh | Device for scanning test areas on test strips |
| NL8602519A (en) * | 1986-10-08 | 1988-05-02 | Philips Nv | LUMINESCENT QUARTZ GLASS, METHOD FOR PREPARING SUCH A GLASS AND LUMINESCENT SCREEN PROVIDED WITH SUCH A GLASS. |
| GB8624587D0 (en) * | 1986-10-14 | 1986-11-19 | North Sea Instr Ltd | Particle analysis apparatus |
| GB8629283D0 (en) * | 1986-12-08 | 1987-01-14 | Gen Electric Co Plc | Radiation meters |
| DE3642275A1 (en) * | 1986-12-11 | 1988-06-23 | Kernforschungsanlage Juelich | INLET SYSTEM FOR PHOTODETECTORS WITH 180 (DEGREES) IMAGE ANGLE AND DETECTORS THEREFORE |
| GB2204678A (en) * | 1987-03-26 | 1988-11-16 | Joshua Swithenbank | Size and velocity measuring instrument for multiphase flows |
-
1989
- 1989-05-30 DE DE3917571A patent/DE3917571A1/en active Granted
-
1990
- 1990-05-11 EP EP90108950A patent/EP0402633B1/en not_active Expired - Lifetime
- 1990-05-11 DE DE90108950T patent/DE59003845D1/en not_active Expired - Fee Related
- 1990-05-17 CA CA002017031A patent/CA2017031A1/en not_active Abandoned
- 1990-05-28 DD DD90341064A patent/DD294794A5/en not_active IP Right Cessation
- 1990-05-29 JP JP2137330A patent/JPH03214038A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010058102A1 (en) | 2008-11-18 | 2010-05-27 | Centre National De La Recherche Scientifique - Cnrs - | Method and system for analysing solid particles in a medium |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3917571A1 (en) | 1990-12-06 |
| DE59003845D1 (en) | 1994-01-27 |
| DE3917571C2 (en) | 1991-08-14 |
| EP0402633B1 (en) | 1993-12-15 |
| EP0402633A1 (en) | 1990-12-19 |
| DD294794A5 (en) | 1991-10-10 |
| JPH03214038A (en) | 1991-09-19 |
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