CA1159674A - Method and apparatus for determining the diameter of a particle in suspension in a fluid using coherent electromagnetic radiation - Google Patents
Method and apparatus for determining the diameter of a particle in suspension in a fluid using coherent electromagnetic radiationInfo
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- CA1159674A CA1159674A CA000371516A CA371516A CA1159674A CA 1159674 A CA1159674 A CA 1159674A CA 000371516 A CA000371516 A CA 000371516A CA 371516 A CA371516 A CA 371516A CA 1159674 A CA1159674 A CA 1159674A
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- determining
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- 239000002245 particle Substances 0.000 title claims abstract description 106
- 238000000034 method Methods 0.000 title claims abstract description 36
- 230000001427 coherent effect Effects 0.000 title claims abstract description 11
- 230000005670 electromagnetic radiation Effects 0.000 title claims abstract description 11
- 239000012530 fluid Substances 0.000 title claims abstract description 10
- 239000000725 suspension Substances 0.000 title claims abstract description 7
- 230000005855 radiation Effects 0.000 claims abstract description 41
- 238000005259 measurement Methods 0.000 claims description 7
- 230000002093 peripheral effect Effects 0.000 claims description 5
- 238000010521 absorption reaction Methods 0.000 claims description 2
- 238000004364 calculation method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000002226 simultaneous effect Effects 0.000 description 2
- 241001508687 Mustela erminea Species 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000011088 calibration curve Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000007866 imination reaction Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
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- 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
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- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Immunology (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- Dispersion Chemistry (AREA)
- Analytical Chemistry (AREA)
- Pathology (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Length-Measuring Devices Using Wave Or Particle Radiation (AREA)
- Length Measuring Devices With Unspecified Measuring Means (AREA)
Abstract
ABSTRACT OF DISCLOSURE
A method and apparatus for determining the diameter of a particle in suspension in a fluid using coherent electromagnetic radiation is disclosed. A parallel beam of coherent electromagnetic radiation is directed towards the particle and the diffused radiation is collected in a predetermined direction. The diameter is defined by the ratio between the diameter of the particle in the predetermined direction and the incident radiation energy. The minimum angle of deviation between the axis of incident radiation and collection of diffused radiation so that there is one-to-one correspondence between the diffused energy and the diameter is determined. The radiation collecting angle is selected to be equal to or greater than the minimum angle. The incident beam is corrected,for example,by a first afocal system for enlarging the section of the beam and then correcting filter and a second afocal system for reducing the section to a suitable size.
The diameters of particles which may be determined ranged between 0.5 and 200 micrometers, Simultaneous determination of particle velocity may also be provided.
A method and apparatus for determining the diameter of a particle in suspension in a fluid using coherent electromagnetic radiation is disclosed. A parallel beam of coherent electromagnetic radiation is directed towards the particle and the diffused radiation is collected in a predetermined direction. The diameter is defined by the ratio between the diameter of the particle in the predetermined direction and the incident radiation energy. The minimum angle of deviation between the axis of incident radiation and collection of diffused radiation so that there is one-to-one correspondence between the diffused energy and the diameter is determined. The radiation collecting angle is selected to be equal to or greater than the minimum angle. The incident beam is corrected,for example,by a first afocal system for enlarging the section of the beam and then correcting filter and a second afocal system for reducing the section to a suitable size.
The diameters of particles which may be determined ranged between 0.5 and 200 micrometers, Simultaneous determination of particle velocity may also be provided.
Description
Field_of the Invention :
~ he present invention relates to a method and apparatus for determining the diameter of particles in suspension in a fluid.
_c]cqround of the Inve ti n :
As opposed to other methods of determination, optical method based on the study of light reflected by the particle have the advantage of not disturbing or suppressing the flow of the fluid in which the particles are in suspension and therefore do not preclude simulta-neous de~ermination of the velocity of the particle.
Particle-sizing of large diameter particles, e.g., greater than 100 micrometers, may be attempted by appli-cation of the la~Ns of geometrical optics by lighting the particles with a beam of white light and analyzing the light reflected in a direction perpendicular to the incident light.
It has ~een demonstrated (cf. the article by J. ~zve, Applied Optics, t.8, vol. 1, 1969, pp. 155-164) thzt such ~ method would not be satisfactory for trans~arent particles having diameters less than 100 micrometers.
In instances where such methods cannot be enployed it would be ternptil1g to use coherent electromagnetic radiation such 2S emitted ~y a lzser. It woul2 also be ,, 1 .
tempti.ng to '.ISe such coherent radiation irrespec~ive Of the particle size in o.der to taXe advantage of the greater light intensities and other advantages inhérent in laser radiation. However; one is then confronted with entirely new problems since the diffusion of such radia-tion is not in general governed by the laws of geometrical optics but the Lorenz-Mie laws which are different. These laws are usable, here, gener~lly for particles having diameters ranging from 0.5 to 200 micrometers and beyond (cf. "Beitrage zur Optik truber Medien", G. Mie, Ann21en der Physik 1908, IV, Folge, Band 25i.
If, by application of the Lorenz-Mie'laws, one calcula.es intensity of the'radiation diffused in different directions for a radiation of glven nature (wavelength, polarization~ strlkiny a given particle, and plots the'results of these'calculations on a polar diagram centered at the'particle, a figure'is obtained comprising a number of lobes with accentuated minima in the privile-ged directions, the position and the size of the lobes varying with the incident radiation and Lhe properties of .
the' particle,' namel'y lts size.
It will therefore be'understooa that it is theore-tically possible to determine the particle size from the intensity bf the'radiation diffused in a predetermjned direction if the radiation does not vary and the nat~re of the parti~le'is constant.
In pr~tice one is confronted with cer~ain diffic~llties.
,. ~
,- , . - ~ .
, ~ne such ~iE-ficuity is that the displacemert of -.he 1O~C
of the polar diagram as a function of the particle size is such th~t there is not a one-to-one correspondence between the diffused intensity and the diame-ter of the particle, i.e., at a given intensity there may be a plura lity of corresponding diameter values.
To overcome'this dlfficulty it has been proposed by F. Durst and H. Umhauer, SFB report 80/EM/81, University of Karlsruhe, February 1976, to use white light.
The'irregulari.ties of the curves expressing, for a given wavelength, the'relatlon. between the intensity of diffused light and the diameter of the'particle;' are at different places for different wa~elengths, nd therefore.
one could hope to obtain onC -to-one'correspondence by using white light which' may be verified in particular when the diffused llght is observed in a direction perpendicular to the incident radiation. The drawback of this method lies in the'`impossibility of focusing the white light uniformly at a great distance from an optical focuslng system ; and it ls therefore impossib'le to study large area fluid flows or high temperature fluid flows. Moreover one is confronted with problems O r discrimination of stray light, parti.cularly stray light emitted by particles due'to the temperature. Such a method therefore'only has uses in rather limited fieIds such as biological analysis~
The use of monochromatic li.ght requires that other - :, ~ , , .: :
, ;7~
methods be fcuncl to resolve t'ne problem caused by the lack of a one-to-one correspondence between the particle diameter and the diffused intensity. One is, in additior~, confronted with a new problem : to obtain sufficient intensity one must have recourse to laser beams but present-day laser beams emit a light beam which has a nonhomogeneous cross section according to a Gaussian function with a maximum along the axi.s of the beam. ~arious method ha~e been proposed to take. this peculiari.ty into lQ account or even to take advantage of it, either by analyzing the variation per unit time of the energy diffused by the particle cross the beam (cf. E. Dan Hirleman, Optics Letters; Vol..3, N l, (July 1978), pp.19~21~ or by comparing the intensities diffused '~y t'ne particle at the same time in directions makin~
different angles with the axis of the incident beam .
(cf. C.CO Gravatt, Journal of the Air Pollution Control Associ.ation, Vol. 32, N (december 1973), pp 1035-1038 or J. Raymond Hadkinson, Applied Optics, vol. 5, n 5, 20 . (may 1956) pp.839-843). These methods require the use of complicated equipment. Further, the range of diameters in whlch they are operative is lir,llted. It follows from the~above-mentioned publications relative to the compari-son of diffused intensities i.n different directions that the range in which the method is operative is greater when operating closer to the axis of the incidcnt beam.
The pickups therefore have to be placed close to the a~is .
: :.
:
of the ln~ident rsdiatjon ~hic-h poses additio~a1, ~ oblem, to avoid disturbirg the same.
~i_____a~d SummarY of the Invéntion :
_ An object or the present invention therefore is to provide a method for ~easuring the size of particles in a range of diameters between 0.5 and 200 micrometers ~-hich may be carrièd out with slmple, inexpensive equipment.
Another object of the'invention ls the provision of such a method ~hich may easily be combined with a method for simultaneously measuring the vel'ocity of the same particle.
According to the invention there is provided a method for determining the diameter of a particle in suspensior in a Eluid by using coherent electromagnetic radiation, the method comprising dixecting a substantially parallel beam of electromagnetic radiation at the particle, collec-ting the'radiation diffused by the particle in a predeter-mined direction, defining the diameter of the particle by using the ratio between the energy diffused in the predetermined directior and the incident radlation energy.
The invention is characterized by determining for the nature of the particle bei'ng examined the minimum angl_ of deviation along which the' dlffused radiation is collec-ted so that there ls subqtantially one-to-one correspon-dence betl~een the di,ffused ener'gy and the diameter of theparticles in the range consideredA The radiation collec-'in~ angle is selected ln relatio~ to the axis of the incident beam at least equal to the minimum angle of ., , ~ . .
': ' ~ ' , ; ~: .
devlation. ~he beam i.s correc~ed before reaching the pa~ticle so that the energy density of the be3m is subs-tantially constant across the'entire'cross section of the incident beam.
The starting point for the invention was the surp~i-sing discover'y that when' sufficiently remote irom the axis of the incident light the relation between the diffused energy and the diameter-tends to be'in one-to-one corres-pondence. The anale at which this fact is established with sufficient precision in pra~ice depends on the nature of the particle. For example the angular diverge~ce of about 20O be~wee'n the incident ray axis and that of the in.
diffused ray to be studied is/general sufficient if the particle is in a very opaque substance'whereas if it is transpa,ent it must ~e close to 90. .
The fact that the relation is in one-to-one corres-pondence'does' not necessarily signify that the lobes of the polar diagram mentioned above wil~ have disappeared nor that they remain stationary when the size of the' particle variesO In fact'it suffices that the variation of the energy diffused during the displacement, of the lobes is, for a given variation of the size of the parti-cle-, less than that whi.ch corresponds to the overall change o~ the'energy which, as is known, increases with the size of the particle.
It may seem astonishing that such a findin~ had not heretofore been ~,ade altho~lgh the Mie 'theory dates back to .l908. The reason is perhaps that this theory leads to more ~, . ' ' , ' :
complicated calculatior~ when examinir~a in creasingly large~
particles and simplified calculations are of decreaslng useful~ess as one moves away from the direction of the incident beam, especially if the particle is large and little transparent. Researchers therefore first directed their efforts on small angles' ; it has moreover been found as stated above, that it is more advantageous in theory to take'angles' which are not too large.
It was only through programs worked out by us tha-t the'investigation could reach large sizes and refraction indexes.
Nonethless the choice of sizable angles taking advantage'of this discovery, would not alone permit a workable method to'be achi'eved if it were not combined with th~ means to insure consta.nt energy across the entire cross section of the' incident beam.' It is in fact absurd to speak of one-to-one 'correspondence in the relation between diffused energy and the particle size if the di~fused energy depends on the distance o~ the particle 2Q from the axis of the beam, for the same'diffused energy may correspond to two different particles,.the larger near the'edge'of the beam and the smaller near its axis.
The use'of a corrector syst~m to insure uniform lighting is classic in conventional optics, but its application to a laser beam in an apparatus for determining particle diameter was not to our knowledge earlier proposed at le.ast in such an app].i-cation. The reason is no do~lbt that there was no nee'd and otner methods, as mentioned ~:; 7-... ~ .. . . . . . ~ . " ~
- - . : , , ~.
- ~ ~ . ~ ..... ..
, ~ : . :. - :, . `:.' ' ~,,~ ' ~'' l5~
abO~e~ had been used to ta~e into account the particul2r structure of lase beams.
The present invention will now be described in grea-ter detail with reference to an embodiment of an apparatus for carrying out the me-thod illustrated in the accompany-ing drawings.
Brief De riPtion of the Dr'awinqs .
Fig. 1 is an overall 'schematic showing o the apparatus embodying the invention; and Fic;. 2 is an overal schematlc showing of an alterna-tive'em'oodiment of the lnvention.
Detailed nescription of_the preferr-ed Embodiments :
The apparatus disclosed permits the simultaneous measurement of the velocity and the diameter of individual partic~ies.
The'apparatus lllustrated in Fig. 1 ~omprises an argon laser emltter 1 adapted to emit radiation at two different wavelengths simultaneously. A semi-transparent glass plate 2 splits the beam into two smaller beams and a specific filter 3,4 lS placed in each of these partial heams to allow one wavelength to pass.Thus, for the sake of simplifying the discussion, one of the partial beams will be'referre~ to as the "blue" beam and the ot:her, the "green" beam. A mirror deflects one of the beams towards the'other in the measurl~g zone 6. The blue beam is used to de1,ermine the diameter of the particle. Before reachincJ
i,he me2suring zc~e it passes through a beam corr~ctor design2ted overall by reference nu~eral 7 and comprising a .
, . -`
~S~F;7~
first aLoc21 system produclng a parallel beam cGnsidera-bly broader than the in~cident beam, a correcting filter 9 having an absorption density greater at the center than the periphery, and a'second afocal system 10 bringing down the diameter of the beam to a suitable vaiue, of the order of that of the incident beam. The reason for the presence of two afocal systemsis simply that the energy density of the laser beam is such that if it were reduced by enlarging the beam the`correcting filter 9 would quickly be put oui of order by overheating. The characte-ristics of the afocal ~ystem 8 are calculated so that the ener~y absorbed by the''correcting filter 7 is dissipated without unduly increasing the'temperature.The manufacture and ajustment a-e also easier. Thecharacteristics of the afocal system 10 are'2es'igned to¦define dimensions of the measuring zone wnich must be'large enough to permit rather fastcounting but narrow enough to el'iminate multiple counting.
. .
A corrected laser beam, such as emerging from the ~0 apparatus, comprises a central area where the'radiation density is uniform and a peripheral area where the density tapers off sharply away from the axls. The peripher21 area may be eIiminated bv a sultable diaphragm stop. It is also possible to eliminate it electronically. Indeed the dif*used intensity of a partlc]e traversing such a beam starts by increasiny during t'ne passage across peripheral area then is constant during its passage across the c~ntral area, and finally decreases durin~ its second . g ' . .
- ! ' , , . . : ~
;, . .
~ ~5~3~791 cros~sing Or 'he peripheral area. It is po~sible to eli~inate the counting of particles wnich emit a signal having a constant portion, i.e., during which the signal varies little per unit time,' which has a duration less than a predetermined value.' It i~ also thus possible'to eliminate the particles whi.ch pass too close to the edge of the central area and thereore would yield questionable'values, since part of their surface would lie outside of the central area.
It is at least theoretically possible to use corrective'systems of a dif.ferent type from that which lS ~cribed above, comprising, -e.g.; nonspherical lense.s, but such lenses are'not readily available and are expensi-ve. With such corrective devlces one does not avoid the above-mentioned problems of el'imination of particles which do not ~ass sufficiently close to the middle of the central zone of the beam. These ~roblems could be overcome in an analogous manner.
The'device for e~amlning thé diffused beam is arranged with its axis perpendi.cular to the incident blue heam. It comprisés a filter 11 adapted to eliminate stray light, namel'y that of the 'green beam, a lens lla which combines the measuring zone.with the rec~eir, a diaphragm stop lIb'for limiting the'opening of the beam to be examined, a slit llc ~or adjustiny the dimensions of the measuri.ng zone, and a convelltional photomultiplier ~2.
In practice the diaphragm stop llb limits the spread of the beam to be examined to an angle'of ~ but which could ' ~`' 1 0 .., ..
.
, , , , , :
` ~59~
be made greater as seen hereinbelow, The green beam is assigned to the simultaneous measurement of the velocity of the particles whose diameter is to be determined, In another embodiment of the apparatus two dif-ferent monochromatic laser emitters 1, la ~urnish the blue beam for determining the diameter and the blue beam for determining the velocity.
In Fig, 1 the laser emitter la used for deter-mining the diameters producing the green beam~s in dashed li-nes,In the embodiment the laser emitter 1 on its own serves to determine the velocity of the particles, the semi-trans-parent plate 2,filters 3,4 and mirror5 are all eliminated.
This embodiment istherefore simpler than the previous em-bodiment but it requires two las~rsinstead of one, The part of the apparatus corresponding to the velocity measurement utilizes the method disclosed in the article by John L, Angus et al,, "Motion Measurement by la ser Doppler Techniques"~ Industrial and Engineering Chemis--try, Vol . 69, n 2 ~February 1969), p,8 et seq, It com-prises a beam splitter 13 which produces two p~rallel beams directed by a lens 14 towards the measuring zone 6, A se-cond photomultiplier lS lies along the bisector of the angle formed by the two beams and preceded by a lens 16 and a filter for eliminating the radiation which does not corres-pond to~rthe green beam, The photomultiplier is connected to an analyser 18 which determines the Doppler requency and the frequency shift ~Jhich corresponds to~he fluctuations of the ~................................. 11 ' , ::. ~ . .. .
, .
:: ~
:' ~ i , ~ ` , .
59Ç;74 velocityO
The signals from the photomultiplier 12 are delivered to the photomultiplier 15 so as to trigger the counting of signals therefrom when a particle is pr~sent in the measuring zone and to electronic circuity 19 for acquisition of amplitude data. The signa].s emitted by the analyzer 18 and amplltude analyzer circuit 19 are delivered to a recording device 20 in a series o~ simul-taneous amplitude (or diameter) and frequency (velocity) data.
Circuit 14 may include discrimlnation means for signals corresponding to particles which do not pass through the central area or pass too close to the edges as indicated above.
In a preferred embodiment advantage is taken of the fact that the beam correcting device provides a measuring zone for the determination of the dlameter which i.5 larger than the measuring zone for the determination of the velocity. Typically the measuring zone for measuring the di.ameters of part.icles is of cylindrical configuration.
The diameter of the cvllnder lS equal to that of t-.he central area of the blue beam, in which the radiation , dens;ty is uniform, and is of the order, of 600 microme-ters. The length of the measuring zone for particle diameters is adjusted by slit llc and it is chosen to be of the order of 50 to 1000 micrometers; this length being about ten ttimes the diameter of ~he part.icles to be analyzed.
., 1 ~ ~5~i~` ~
The measuring zone for the velocity of the particles has rcughly an elongated ellipsoidal configuration whose lar~est diameter is 300 micromèters and whose smallest diameter is about 50 micrometers. It is seen that if the two measuring zones are suitably arranged with respect to each other the velocity measur1ng zone'lies entirely inside 'the'blue beam. Under thes'e circumstances it is -not abs'olutely necessary to provide'the'electronic discriminating mean~ disclosed hereinabove for eliminating the counting of particles which do not pass through the central area of the blue'be'am or too close to the edge thereof. They may be el'iminated more'simply by eliminating in the recording de~ice'any d1ameter determining signal for which'there'is no coi'ncident vel'ocity cletermining signal.
The 'other methods of eliminating diameter signals to corres'ponding/particles which''are'not in the correct position are 'obviously nece's'sary when no simultaneous determin~,tion of velocity is rnade.' It will be noted that in any event the're~ording device 'furnishes, or very easily permi~s the calculation of the'concentration of particles' in the fluid medium in which 'it is susipended~ Thi's concentration ascertained ~rom th~ 'number of partlcles measured during a given period o~ ~ime,' the'dlme.nsions o ~he measurlng æone, and the velocity o~ the parl:icles' with respect to the measu~
ring Yon~.
Fig. 2 illll,strates' anothe`r emhodiment o~ the ',; 13 :
' apparatus according to the invention whic'n permits the simultaneous detexmination of particle size ~nd velocity.
The measuring zone 6 receives radiation from two corrected laser'beams whose radiation density is uniform in the central area. These two beams are arranged to produce an interference 'zone adapted to be used for measurement b-~ Doppler effect. They are produced from a single beam emerging from a laser emitter 1 and are corrected by a beam correct'ing filter 7 of the same type as described hereinabove. A beam splitter 13 placed in the path of the' correct beam furnishes two parallel beams which 'are'deflected by two mirrors 21a, 21b in order to reach the measuritlg zone 6.
The analyzing or e~amining apparatus comprises a~s in the case of the Fig. 1 embodiment a photomultiplier 12 preceded by lens lla, a diaphragm stop 11 b and a slit ll'c. A filter 11 is not necessary in the absence of stray light. These elements are placed so that for both of the incident beams there'is a one-to-one correspondence between the diffused energy and the diameter.of the particle.
The''el'ectronic circuitry ~hichprocesses the signals leaving the photomultiplier tak~ into ac0untthe fact that thesesignals-are carriers of two information outputs :
the overall amp].itude of the signal related to a particle corresponds to the diameler of this particle, and the signal includes a high frequerlcy modulation which is the Doppler frer~uency and corresponcls to the velocity of the ' 1.'1 ' ' ' 3~
particle. The signals are therefore deliv2red to an analyzer 18 which determines the Doppler frequency and increase of this frequency which corresponds to fluctua-tions of the velocity, and a circuit 19 for acquisition of data relative to the amplitudes which comprises means ~or eliminatina the counting of signals corresponding to particles which are not in a correct position in relation to measuring zone'as indicated a'oove.
The signals leaving the analyzer 18 and the circuit 19 are delivered to-the device 20 for recording simul-ta-neous part~cle'diameter, vel'oclty and concentration data as explained above.
This second embodiment has the advantage of greater simplicity by u~ing a single'receiver. On the other hand 1~ the precision is reduced by increasinq edge effects and the measuring zone is enlarged.
Such apparatus ar'e'suitable for a very wide range of opaque and transparent particles, in particular, particle'diameters from 0.5 to'200 micrometers.
In the case of transparent particles it is possible to improve precision of diameter measurement by measuring the diff-used intensity at two wavel'engths simultaneously, and/or enlarging the'radiation collecting angle for the diffused radiation by regulating the diaphragm stop llb so as to reduce irregularities in the'curves of the intensjiy as a function or the diameter.
Altho~yh we have referred to particle diameter, obviousiy nonspherical partlc~es may be examined in which '~' 15 ,. . .
,: . : ~, .
:
case an apparent'diameter is determined.
The'caiibration of the apparatus cannot be carrie2 out only by calculations by reason of the lack of preci-sion o the data'that may be had Ylth regard to the componen'ts such as photomultipliers. In practice the shape of the signal/particle diameter curve is determined by calculations and the curve is "locked in" by means of particle samples of known dimensions determined by means of a mlcroscope for example.' In case the particles are of lrregu]ar shape it may be preferable to plot the calibration curve empirically by means of a sufficient number of samples.
... .
,
~ he present invention relates to a method and apparatus for determining the diameter of particles in suspension in a fluid.
_c]cqround of the Inve ti n :
As opposed to other methods of determination, optical method based on the study of light reflected by the particle have the advantage of not disturbing or suppressing the flow of the fluid in which the particles are in suspension and therefore do not preclude simulta-neous de~ermination of the velocity of the particle.
Particle-sizing of large diameter particles, e.g., greater than 100 micrometers, may be attempted by appli-cation of the la~Ns of geometrical optics by lighting the particles with a beam of white light and analyzing the light reflected in a direction perpendicular to the incident light.
It has ~een demonstrated (cf. the article by J. ~zve, Applied Optics, t.8, vol. 1, 1969, pp. 155-164) thzt such ~ method would not be satisfactory for trans~arent particles having diameters less than 100 micrometers.
In instances where such methods cannot be enployed it would be ternptil1g to use coherent electromagnetic radiation such 2S emitted ~y a lzser. It woul2 also be ,, 1 .
tempti.ng to '.ISe such coherent radiation irrespec~ive Of the particle size in o.der to taXe advantage of the greater light intensities and other advantages inhérent in laser radiation. However; one is then confronted with entirely new problems since the diffusion of such radia-tion is not in general governed by the laws of geometrical optics but the Lorenz-Mie laws which are different. These laws are usable, here, gener~lly for particles having diameters ranging from 0.5 to 200 micrometers and beyond (cf. "Beitrage zur Optik truber Medien", G. Mie, Ann21en der Physik 1908, IV, Folge, Band 25i.
If, by application of the Lorenz-Mie'laws, one calcula.es intensity of the'radiation diffused in different directions for a radiation of glven nature (wavelength, polarization~ strlkiny a given particle, and plots the'results of these'calculations on a polar diagram centered at the'particle, a figure'is obtained comprising a number of lobes with accentuated minima in the privile-ged directions, the position and the size of the lobes varying with the incident radiation and Lhe properties of .
the' particle,' namel'y lts size.
It will therefore be'understooa that it is theore-tically possible to determine the particle size from the intensity bf the'radiation diffused in a predetermjned direction if the radiation does not vary and the nat~re of the parti~le'is constant.
In pr~tice one is confronted with cer~ain diffic~llties.
,. ~
,- , . - ~ .
, ~ne such ~iE-ficuity is that the displacemert of -.he 1O~C
of the polar diagram as a function of the particle size is such th~t there is not a one-to-one correspondence between the diffused intensity and the diame-ter of the particle, i.e., at a given intensity there may be a plura lity of corresponding diameter values.
To overcome'this dlfficulty it has been proposed by F. Durst and H. Umhauer, SFB report 80/EM/81, University of Karlsruhe, February 1976, to use white light.
The'irregulari.ties of the curves expressing, for a given wavelength, the'relatlon. between the intensity of diffused light and the diameter of the'particle;' are at different places for different wa~elengths, nd therefore.
one could hope to obtain onC -to-one'correspondence by using white light which' may be verified in particular when the diffused llght is observed in a direction perpendicular to the incident radiation. The drawback of this method lies in the'`impossibility of focusing the white light uniformly at a great distance from an optical focuslng system ; and it ls therefore impossib'le to study large area fluid flows or high temperature fluid flows. Moreover one is confronted with problems O r discrimination of stray light, parti.cularly stray light emitted by particles due'to the temperature. Such a method therefore'only has uses in rather limited fieIds such as biological analysis~
The use of monochromatic li.ght requires that other - :, ~ , , .: :
, ;7~
methods be fcuncl to resolve t'ne problem caused by the lack of a one-to-one correspondence between the particle diameter and the diffused intensity. One is, in additior~, confronted with a new problem : to obtain sufficient intensity one must have recourse to laser beams but present-day laser beams emit a light beam which has a nonhomogeneous cross section according to a Gaussian function with a maximum along the axi.s of the beam. ~arious method ha~e been proposed to take. this peculiari.ty into lQ account or even to take advantage of it, either by analyzing the variation per unit time of the energy diffused by the particle cross the beam (cf. E. Dan Hirleman, Optics Letters; Vol..3, N l, (July 1978), pp.19~21~ or by comparing the intensities diffused '~y t'ne particle at the same time in directions makin~
different angles with the axis of the incident beam .
(cf. C.CO Gravatt, Journal of the Air Pollution Control Associ.ation, Vol. 32, N (december 1973), pp 1035-1038 or J. Raymond Hadkinson, Applied Optics, vol. 5, n 5, 20 . (may 1956) pp.839-843). These methods require the use of complicated equipment. Further, the range of diameters in whlch they are operative is lir,llted. It follows from the~above-mentioned publications relative to the compari-son of diffused intensities i.n different directions that the range in which the method is operative is greater when operating closer to the axis of the incidcnt beam.
The pickups therefore have to be placed close to the a~is .
: :.
:
of the ln~ident rsdiatjon ~hic-h poses additio~a1, ~ oblem, to avoid disturbirg the same.
~i_____a~d SummarY of the Invéntion :
_ An object or the present invention therefore is to provide a method for ~easuring the size of particles in a range of diameters between 0.5 and 200 micrometers ~-hich may be carrièd out with slmple, inexpensive equipment.
Another object of the'invention ls the provision of such a method ~hich may easily be combined with a method for simultaneously measuring the vel'ocity of the same particle.
According to the invention there is provided a method for determining the diameter of a particle in suspensior in a Eluid by using coherent electromagnetic radiation, the method comprising dixecting a substantially parallel beam of electromagnetic radiation at the particle, collec-ting the'radiation diffused by the particle in a predeter-mined direction, defining the diameter of the particle by using the ratio between the energy diffused in the predetermined directior and the incident radlation energy.
The invention is characterized by determining for the nature of the particle bei'ng examined the minimum angl_ of deviation along which the' dlffused radiation is collec-ted so that there ls subqtantially one-to-one correspon-dence betl~een the di,ffused ener'gy and the diameter of theparticles in the range consideredA The radiation collec-'in~ angle is selected ln relatio~ to the axis of the incident beam at least equal to the minimum angle of ., , ~ . .
': ' ~ ' , ; ~: .
devlation. ~he beam i.s correc~ed before reaching the pa~ticle so that the energy density of the be3m is subs-tantially constant across the'entire'cross section of the incident beam.
The starting point for the invention was the surp~i-sing discover'y that when' sufficiently remote irom the axis of the incident light the relation between the diffused energy and the diameter-tends to be'in one-to-one corres-pondence. The anale at which this fact is established with sufficient precision in pra~ice depends on the nature of the particle. For example the angular diverge~ce of about 20O be~wee'n the incident ray axis and that of the in.
diffused ray to be studied is/general sufficient if the particle is in a very opaque substance'whereas if it is transpa,ent it must ~e close to 90. .
The fact that the relation is in one-to-one corres-pondence'does' not necessarily signify that the lobes of the polar diagram mentioned above wil~ have disappeared nor that they remain stationary when the size of the' particle variesO In fact'it suffices that the variation of the energy diffused during the displacement, of the lobes is, for a given variation of the size of the parti-cle-, less than that whi.ch corresponds to the overall change o~ the'energy which, as is known, increases with the size of the particle.
It may seem astonishing that such a findin~ had not heretofore been ~,ade altho~lgh the Mie 'theory dates back to .l908. The reason is perhaps that this theory leads to more ~, . ' ' , ' :
complicated calculatior~ when examinir~a in creasingly large~
particles and simplified calculations are of decreaslng useful~ess as one moves away from the direction of the incident beam, especially if the particle is large and little transparent. Researchers therefore first directed their efforts on small angles' ; it has moreover been found as stated above, that it is more advantageous in theory to take'angles' which are not too large.
It was only through programs worked out by us tha-t the'investigation could reach large sizes and refraction indexes.
Nonethless the choice of sizable angles taking advantage'of this discovery, would not alone permit a workable method to'be achi'eved if it were not combined with th~ means to insure consta.nt energy across the entire cross section of the' incident beam.' It is in fact absurd to speak of one-to-one 'correspondence in the relation between diffused energy and the particle size if the di~fused energy depends on the distance o~ the particle 2Q from the axis of the beam, for the same'diffused energy may correspond to two different particles,.the larger near the'edge'of the beam and the smaller near its axis.
The use'of a corrector syst~m to insure uniform lighting is classic in conventional optics, but its application to a laser beam in an apparatus for determining particle diameter was not to our knowledge earlier proposed at le.ast in such an app].i-cation. The reason is no do~lbt that there was no nee'd and otner methods, as mentioned ~:; 7-... ~ .. . . . . . ~ . " ~
- - . : , , ~.
- ~ ~ . ~ ..... ..
, ~ : . :. - :, . `:.' ' ~,,~ ' ~'' l5~
abO~e~ had been used to ta~e into account the particul2r structure of lase beams.
The present invention will now be described in grea-ter detail with reference to an embodiment of an apparatus for carrying out the me-thod illustrated in the accompany-ing drawings.
Brief De riPtion of the Dr'awinqs .
Fig. 1 is an overall 'schematic showing o the apparatus embodying the invention; and Fic;. 2 is an overal schematlc showing of an alterna-tive'em'oodiment of the lnvention.
Detailed nescription of_the preferr-ed Embodiments :
The apparatus disclosed permits the simultaneous measurement of the velocity and the diameter of individual partic~ies.
The'apparatus lllustrated in Fig. 1 ~omprises an argon laser emltter 1 adapted to emit radiation at two different wavelengths simultaneously. A semi-transparent glass plate 2 splits the beam into two smaller beams and a specific filter 3,4 lS placed in each of these partial heams to allow one wavelength to pass.Thus, for the sake of simplifying the discussion, one of the partial beams will be'referre~ to as the "blue" beam and the ot:her, the "green" beam. A mirror deflects one of the beams towards the'other in the measurl~g zone 6. The blue beam is used to de1,ermine the diameter of the particle. Before reachincJ
i,he me2suring zc~e it passes through a beam corr~ctor design2ted overall by reference nu~eral 7 and comprising a .
, . -`
~S~F;7~
first aLoc21 system produclng a parallel beam cGnsidera-bly broader than the in~cident beam, a correcting filter 9 having an absorption density greater at the center than the periphery, and a'second afocal system 10 bringing down the diameter of the beam to a suitable vaiue, of the order of that of the incident beam. The reason for the presence of two afocal systemsis simply that the energy density of the laser beam is such that if it were reduced by enlarging the beam the`correcting filter 9 would quickly be put oui of order by overheating. The characte-ristics of the afocal ~ystem 8 are calculated so that the ener~y absorbed by the''correcting filter 7 is dissipated without unduly increasing the'temperature.The manufacture and ajustment a-e also easier. Thecharacteristics of the afocal system 10 are'2es'igned to¦define dimensions of the measuring zone wnich must be'large enough to permit rather fastcounting but narrow enough to el'iminate multiple counting.
. .
A corrected laser beam, such as emerging from the ~0 apparatus, comprises a central area where the'radiation density is uniform and a peripheral area where the density tapers off sharply away from the axls. The peripher21 area may be eIiminated bv a sultable diaphragm stop. It is also possible to eliminate it electronically. Indeed the dif*used intensity of a partlc]e traversing such a beam starts by increasiny during t'ne passage across peripheral area then is constant during its passage across the c~ntral area, and finally decreases durin~ its second . g ' . .
- ! ' , , . . : ~
;, . .
~ ~5~3~791 cros~sing Or 'he peripheral area. It is po~sible to eli~inate the counting of particles wnich emit a signal having a constant portion, i.e., during which the signal varies little per unit time,' which has a duration less than a predetermined value.' It i~ also thus possible'to eliminate the particles whi.ch pass too close to the edge of the central area and thereore would yield questionable'values, since part of their surface would lie outside of the central area.
It is at least theoretically possible to use corrective'systems of a dif.ferent type from that which lS ~cribed above, comprising, -e.g.; nonspherical lense.s, but such lenses are'not readily available and are expensi-ve. With such corrective devlces one does not avoid the above-mentioned problems of el'imination of particles which do not ~ass sufficiently close to the middle of the central zone of the beam. These ~roblems could be overcome in an analogous manner.
The'device for e~amlning thé diffused beam is arranged with its axis perpendi.cular to the incident blue heam. It comprisés a filter 11 adapted to eliminate stray light, namel'y that of the 'green beam, a lens lla which combines the measuring zone.with the rec~eir, a diaphragm stop lIb'for limiting the'opening of the beam to be examined, a slit llc ~or adjustiny the dimensions of the measuri.ng zone, and a convelltional photomultiplier ~2.
In practice the diaphragm stop llb limits the spread of the beam to be examined to an angle'of ~ but which could ' ~`' 1 0 .., ..
.
, , , , , :
` ~59~
be made greater as seen hereinbelow, The green beam is assigned to the simultaneous measurement of the velocity of the particles whose diameter is to be determined, In another embodiment of the apparatus two dif-ferent monochromatic laser emitters 1, la ~urnish the blue beam for determining the diameter and the blue beam for determining the velocity.
In Fig, 1 the laser emitter la used for deter-mining the diameters producing the green beam~s in dashed li-nes,In the embodiment the laser emitter 1 on its own serves to determine the velocity of the particles, the semi-trans-parent plate 2,filters 3,4 and mirror5 are all eliminated.
This embodiment istherefore simpler than the previous em-bodiment but it requires two las~rsinstead of one, The part of the apparatus corresponding to the velocity measurement utilizes the method disclosed in the article by John L, Angus et al,, "Motion Measurement by la ser Doppler Techniques"~ Industrial and Engineering Chemis--try, Vol . 69, n 2 ~February 1969), p,8 et seq, It com-prises a beam splitter 13 which produces two p~rallel beams directed by a lens 14 towards the measuring zone 6, A se-cond photomultiplier lS lies along the bisector of the angle formed by the two beams and preceded by a lens 16 and a filter for eliminating the radiation which does not corres-pond to~rthe green beam, The photomultiplier is connected to an analyser 18 which determines the Doppler requency and the frequency shift ~Jhich corresponds to~he fluctuations of the ~................................. 11 ' , ::. ~ . .. .
, .
:: ~
:' ~ i , ~ ` , .
59Ç;74 velocityO
The signals from the photomultiplier 12 are delivered to the photomultiplier 15 so as to trigger the counting of signals therefrom when a particle is pr~sent in the measuring zone and to electronic circuity 19 for acquisition of amplitude data. The signa].s emitted by the analyzer 18 and amplltude analyzer circuit 19 are delivered to a recording device 20 in a series o~ simul-taneous amplitude (or diameter) and frequency (velocity) data.
Circuit 14 may include discrimlnation means for signals corresponding to particles which do not pass through the central area or pass too close to the edges as indicated above.
In a preferred embodiment advantage is taken of the fact that the beam correcting device provides a measuring zone for the determination of the dlameter which i.5 larger than the measuring zone for the determination of the velocity. Typically the measuring zone for measuring the di.ameters of part.icles is of cylindrical configuration.
The diameter of the cvllnder lS equal to that of t-.he central area of the blue beam, in which the radiation , dens;ty is uniform, and is of the order, of 600 microme-ters. The length of the measuring zone for particle diameters is adjusted by slit llc and it is chosen to be of the order of 50 to 1000 micrometers; this length being about ten ttimes the diameter of ~he part.icles to be analyzed.
., 1 ~ ~5~i~` ~
The measuring zone for the velocity of the particles has rcughly an elongated ellipsoidal configuration whose lar~est diameter is 300 micromèters and whose smallest diameter is about 50 micrometers. It is seen that if the two measuring zones are suitably arranged with respect to each other the velocity measur1ng zone'lies entirely inside 'the'blue beam. Under thes'e circumstances it is -not abs'olutely necessary to provide'the'electronic discriminating mean~ disclosed hereinabove for eliminating the counting of particles which do not pass through the central area of the blue'be'am or too close to the edge thereof. They may be el'iminated more'simply by eliminating in the recording de~ice'any d1ameter determining signal for which'there'is no coi'ncident vel'ocity cletermining signal.
The 'other methods of eliminating diameter signals to corres'ponding/particles which''are'not in the correct position are 'obviously nece's'sary when no simultaneous determin~,tion of velocity is rnade.' It will be noted that in any event the're~ording device 'furnishes, or very easily permi~s the calculation of the'concentration of particles' in the fluid medium in which 'it is susipended~ Thi's concentration ascertained ~rom th~ 'number of partlcles measured during a given period o~ ~ime,' the'dlme.nsions o ~he measurlng æone, and the velocity o~ the parl:icles' with respect to the measu~
ring Yon~.
Fig. 2 illll,strates' anothe`r emhodiment o~ the ',; 13 :
' apparatus according to the invention whic'n permits the simultaneous detexmination of particle size ~nd velocity.
The measuring zone 6 receives radiation from two corrected laser'beams whose radiation density is uniform in the central area. These two beams are arranged to produce an interference 'zone adapted to be used for measurement b-~ Doppler effect. They are produced from a single beam emerging from a laser emitter 1 and are corrected by a beam correct'ing filter 7 of the same type as described hereinabove. A beam splitter 13 placed in the path of the' correct beam furnishes two parallel beams which 'are'deflected by two mirrors 21a, 21b in order to reach the measuritlg zone 6.
The analyzing or e~amining apparatus comprises a~s in the case of the Fig. 1 embodiment a photomultiplier 12 preceded by lens lla, a diaphragm stop 11 b and a slit ll'c. A filter 11 is not necessary in the absence of stray light. These elements are placed so that for both of the incident beams there'is a one-to-one correspondence between the diffused energy and the diameter.of the particle.
The''el'ectronic circuitry ~hichprocesses the signals leaving the photomultiplier tak~ into ac0untthe fact that thesesignals-are carriers of two information outputs :
the overall amp].itude of the signal related to a particle corresponds to the diameler of this particle, and the signal includes a high frequerlcy modulation which is the Doppler frer~uency and corresponcls to the velocity of the ' 1.'1 ' ' ' 3~
particle. The signals are therefore deliv2red to an analyzer 18 which determines the Doppler frequency and increase of this frequency which corresponds to fluctua-tions of the velocity, and a circuit 19 for acquisition of data relative to the amplitudes which comprises means ~or eliminatina the counting of signals corresponding to particles which are not in a correct position in relation to measuring zone'as indicated a'oove.
The signals leaving the analyzer 18 and the circuit 19 are delivered to-the device 20 for recording simul-ta-neous part~cle'diameter, vel'oclty and concentration data as explained above.
This second embodiment has the advantage of greater simplicity by u~ing a single'receiver. On the other hand 1~ the precision is reduced by increasinq edge effects and the measuring zone is enlarged.
Such apparatus ar'e'suitable for a very wide range of opaque and transparent particles, in particular, particle'diameters from 0.5 to'200 micrometers.
In the case of transparent particles it is possible to improve precision of diameter measurement by measuring the diff-used intensity at two wavel'engths simultaneously, and/or enlarging the'radiation collecting angle for the diffused radiation by regulating the diaphragm stop llb so as to reduce irregularities in the'curves of the intensjiy as a function or the diameter.
Altho~yh we have referred to particle diameter, obviousiy nonspherical partlc~es may be examined in which '~' 15 ,. . .
,: . : ~, .
:
case an apparent'diameter is determined.
The'caiibration of the apparatus cannot be carrie2 out only by calculations by reason of the lack of preci-sion o the data'that may be had Ylth regard to the componen'ts such as photomultipliers. In practice the shape of the signal/particle diameter curve is determined by calculations and the curve is "locked in" by means of particle samples of known dimensions determined by means of a mlcroscope for example.' In case the particles are of lrregu]ar shape it may be preferable to plot the calibration curve empirically by means of a sufficient number of samples.
... .
,
Claims (21)
1. A method for determining the diameter of a particle in suspension in a fluid by using coherent electromagnetic radiation, said method comprising the steps of : directing a substantially parallel beam of said electromagnetic radiation at the particle, collec-ting the radiation diffused by the particle in a predeter-mined direction, defining the diameter of the particle by using the ratio between the energy diffused in the predetermined direction and the incident radiation energy, determining the minimum angle of deviation between the direction of the axis of the beam and the direction along which the diffused radiation is collected so that there is substantially one-to-one correspondence between the diffused energy and the diameter of the particles in the range of particle considered, selecting a radiation collecting angle in relation to the axis of incident beam at least equal to the minimum angle of deviation, and correcting the beam before reaching the particle so that the energy density of the beam is substantially constant across the entire cross section of the incident beam.
2. A method according to claim 1, wherein the step of correcting the beam comprises successively enlarging the beam and reducing the section of the beam.
3. A method according to claim 1, the diameters of the particles being determined ranging between 0.5 and 200 micrometers.
4. A method according to claim 1, further comprising electronically eliminating the signals corresponding to the particles lying in the nonhomogeneous peripheral area of the corrected beam.
5. A method according to claim 3, further comprising electronically eliminating the signals corresponding to the particles lying in the nonhomogeneous peripheral area of the corrected beam.
6. A method according to claim 4, or 5,further comprising eliminating signals having a constant portion having a duration less than a predetermined value.
7. A method according to claim 1,further comprising simultaneously determining the velocity of the same particle by the Doppler method and processing signals corresponding to the diameter and velocity of the particle in an electronic unit.
8. A method according to claim 3, further comprising simultaneously determining the velocity of the same particle by the Doppler method and processing signals corresponding to the diameter and velocity of the particle in an electronic unit.
9. A method according to claim 7 or 8, further comprising determining the concentration of particles in suspension in the fluid in the same electronic unit.
10. Apparatus for determining the diameter of particles in suspension in a fluid comprising emitter means arranged for directing a parallel incident beam of coherent electromagnetic radiation towards the particle, means for collecting radiation diffused by the particle when it is in the beam, said means for collecting radiation being disposed to receive radiation diffused in a direction which makes an angle greater than the minimum angle for one-to-one correspondence between the diffused energy and the diameter of the particle in the range of particle sizes considered, and a correcting system arranged in the path of the incident beam between the emitter means and the particle so that the energy density remains substantially constant over virtually the entire cross section of the incident beam.
11. Apparatus according to claim 10, wherein said correcting system comprises a correcting filter having an absorption density greater at the center than periphery, said correcting filter being disposed between a first afocal system for producing a wider parallel beam than the incoming beam, and a second afocal system for narrowing the beam to a value suitable for measurement.
12. Apparatus according to claim 10, wherein the radiation collecting means comprises a photomultiplier, and data acquisition electronic circuitry for processing the amplitudes of signals emitted by said photomultiplier.
13. Apparatus according to claim 11,wherein the radiation collecting means comprises a photomultiplier, and data acquisition electronic circuitry for processing the amplitudes of signals emitted by said photomultiplier.
14. Apparatus according to claim 12, wherein said electronic circuitry comprises means for eliminating signals corresponding to particles passing outside the central area of homogeneous density of the corrected incident beam.
15. Apparatus according to claim 13, wherein said electronic circuitry comprises means for eliminating signals corresponding to particles passing outside the central area of homogeneous density of the corrected incident beam.
16. Apparatus according to claim 14, wherein said means for eliminating signals comprises means for determining the duration of the constant amplitude portion of a signal and means for eliminating the counting of a signal when its duration is less than a predeter-mined value.
17. Apparatus according to claim 15, wherein said means for eliminating signals comprises means for determining the duration of the constant amplitude portion of a signal and means for eliminating the counting of a signal when its duration is less than a pre-determined value.
18.Apparatus according to claim 10,further comprising means for determining the velocity of the particle by the Doppler method including means for emitting a beam of coherent electromagnetic radiation, a beam splitter for providing two parallel emergent beams, a lens for converging the two emerging beams in a particle velocity measuring zone whose center is the same as the particle diameter measuring zone, a photomultiplier connected to analyzer means for determining the Doppler frequency, said analyzer means being part of an electronic unit including an electronic circuitry for processing at the same time data received from said radiation collecting means relative to the intensity of radiation diffused by the same particle.
19. Apparatus according to claim 18, wherein said particle velocity measuring zone is disposed entirely within said particle diameter measuring zone, said electro-nic unit comprising means for eliminating particle size determination signals which are not in coincidence with particle velocity signals.
20. Apparatus according to claim 18, there being a single emitter means for emitting two wavelengths of coherent radiation, and means for dividing the emitted beam into two beams having different wavelengths, one of said two beams being used for particle size determination and the other for particle velocity determination.
21. Apparatus according to claim 18, further comprising means for obtaining from said means for emitting a beam of coherent electromagnetic radiation two corrected beams for using in particle size determina-tion, said two corrected beams being directed towards the particle so as to produce Doppler frequencies, single radiation collecting means being disposed to pick up radiation diffused in a direction which makes with each of said two corrected beams an angle greater than a minimum angle for which there is substantially one-to-one correspondence between the diffused energy and the particle diameter in the range of particle sizes considered, and means for using diffused radiation data contained in signals produced by said radiation collecting means and Doppler frequency data contained in said signals produced by said collecting means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8004113A FR2476839A1 (en) | 1980-02-25 | 1980-02-25 | METHOD FOR DETERMINING THE DIAMETER OF A SUSPENDED PARTICLE IN A FLUID BY USING COHERENT ELECTROMAGNETIC RADIATION |
| FR8004.113 | 1980-02-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1159674A true CA1159674A (en) | 1984-01-03 |
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ID=9238933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000371516A Expired CA1159674A (en) | 1980-02-25 | 1981-02-23 | Method and apparatus for determining the diameter of a particle in suspension in a fluid using coherent electromagnetic radiation |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0035437B1 (en) |
| JP (1) | JPS56130639A (en) |
| AT (1) | ATE17524T1 (en) |
| CA (1) | CA1159674A (en) |
| DE (1) | DE3173482D1 (en) |
| FR (1) | FR2476839A1 (en) |
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| US4696571A (en) * | 1985-10-25 | 1987-09-29 | The United States Of America As Represented By The Secretary Of The Interior | Suspended sediment sensor |
| US8315821B2 (en) | 2009-01-13 | 2012-11-20 | New York University | Packing properties of particulate compositions |
| US8791985B2 (en) | 2007-10-30 | 2014-07-29 | New York University | Tracking and characterizing particles with holographic video microscopy |
| US9316578B2 (en) | 2008-10-30 | 2016-04-19 | New York University | Automated real-time particle characterization and three-dimensional velocimetry with holographic video microscopy |
| US10641696B2 (en) | 2015-09-18 | 2020-05-05 | New York University | Holographic detection and characterization of large impurity particles in precision slurries |
| US10670677B2 (en) | 2016-04-22 | 2020-06-02 | New York University | Multi-slice acceleration for magnetic resonance fingerprinting |
| US10983041B2 (en) | 2014-02-12 | 2021-04-20 | New York University | Fast feature identification for holographic tracking and characterization of colloidal particles |
| US11085864B2 (en) | 2014-11-12 | 2021-08-10 | New York University | Colloidal fingerprints for soft materials using total holographic characterization |
| US11385157B2 (en) | 2016-02-08 | 2022-07-12 | New York University | Holographic characterization of protein aggregates |
| US11543338B2 (en) | 2019-10-25 | 2023-01-03 | New York University | Holographic characterization of irregular particles |
| US11948302B2 (en) | 2020-03-09 | 2024-04-02 | New York University | Automated holographic video microscopy assay |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2521294A1 (en) * | 1982-02-05 | 1983-08-12 | Bajard Jean | GLOBAL INTERFERENTIAL GRANULOMETRY METHOD APPLICABLE IN PARTICULAR TO POLYDISPERSE BIOLOGICAL PARTICLES |
| US4537507A (en) * | 1982-10-18 | 1985-08-27 | Spectron Development Laboratories, Inc. | Dual beam maximum intensity laser sizing system |
| AU573436B2 (en) * | 1985-04-11 | 1988-06-09 | Nippon Steel Corporation | Electromagnetic measurement of particle sizes |
| US4662742A (en) * | 1985-05-10 | 1987-05-05 | Becton, Dickinson And Company | Scatter/fluorescene beam splitter in a flow cytometry apparatus |
| DE3806109A1 (en) * | 1987-12-16 | 1989-07-06 | Klaus Prof Dr Ing Baukhage | Method for establishing at least the surface structure of moving spherical particles |
| DE3931119C1 (en) * | 1989-09-18 | 1991-04-11 | Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung Ev, 8000 Muenchen, De | Simultaneously measuring size and speed of particles and bubbles - applying pair of crossing beams of different wavelengths and intensity distribution to multiphase carrying stream |
| US5012118A (en) * | 1989-12-13 | 1991-04-30 | Preikschat F K | Apparatus and method for particle analysis |
| DE4215908A1 (en) * | 1992-05-14 | 1993-11-18 | Ubbo Prof Dr Ricklefs | Optical particle size measurement appts. e.g. for clean room - periodically modulates light incident on measuring vol. e.g by varying light source power or using grating, acoustic=optic modulator or hologram, and detects scattered light. |
| RU2684435C1 (en) * | 2017-10-10 | 2019-04-09 | Российская Федерация, от имени которой выступает Федеральное агентство по техническому регулированию и метрологии (Росстандарт) | Installation for calibration/verification and calibration method for measuring divergence angle of a laser beam |
| EP4121759A1 (en) * | 2020-03-20 | 2023-01-25 | PerkinElmer Health Sciences B.V. | Detecting composition of non-homogenized fluids |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3835315A (en) * | 1972-12-06 | 1974-09-10 | Us Commerce | System for determining parameters of a particle by radiant energy scattering techniques |
| US3851169A (en) * | 1973-11-23 | 1974-11-26 | Gen Motors Corp | Apparatus for measuring aerosol particles |
| US4134679A (en) * | 1976-11-05 | 1979-01-16 | Leeds & Northrup Company | Determining the volume and the volume distribution of suspended small particles |
| US4348111A (en) * | 1978-12-07 | 1982-09-07 | The English Electric Company Limited | Optical particle analyzers |
-
1980
- 1980-02-25 FR FR8004113A patent/FR2476839A1/en active Granted
-
1981
- 1981-02-23 EP EP81400282A patent/EP0035437B1/en not_active Expired
- 1981-02-23 DE DE8181400282T patent/DE3173482D1/en not_active Expired
- 1981-02-23 AT AT81400282T patent/ATE17524T1/en not_active IP Right Cessation
- 1981-02-23 CA CA000371516A patent/CA1159674A/en not_active Expired
- 1981-02-25 JP JP2554881A patent/JPS56130639A/en active Granted
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4696571A (en) * | 1985-10-25 | 1987-09-29 | The United States Of America As Represented By The Secretary Of The Interior | Suspended sediment sensor |
| US8791985B2 (en) | 2007-10-30 | 2014-07-29 | New York University | Tracking and characterizing particles with holographic video microscopy |
| US9810894B2 (en) | 2007-10-30 | 2017-11-07 | New York University | Tracking and characterizing particles with holographic video microscopy |
| US9316578B2 (en) | 2008-10-30 | 2016-04-19 | New York University | Automated real-time particle characterization and three-dimensional velocimetry with holographic video microscopy |
| US8315821B2 (en) | 2009-01-13 | 2012-11-20 | New York University | Packing properties of particulate compositions |
| US10634604B2 (en) | 2009-01-16 | 2020-04-28 | New York University | Automated real-time particle characterization and three-dimensional velocimetry with holographic video microscopy |
| US11892390B2 (en) | 2009-01-16 | 2024-02-06 | New York University | Automated real-time particle characterization and three-dimensional velocimetry with holographic video microscopy |
| US10983041B2 (en) | 2014-02-12 | 2021-04-20 | New York University | Fast feature identification for holographic tracking and characterization of colloidal particles |
| US11085864B2 (en) | 2014-11-12 | 2021-08-10 | New York University | Colloidal fingerprints for soft materials using total holographic characterization |
| US11977015B2 (en) | 2014-11-12 | 2024-05-07 | New York University | Colloidal fingerprints for soft materials using total holographic characterization |
| US10641696B2 (en) | 2015-09-18 | 2020-05-05 | New York University | Holographic detection and characterization of large impurity particles in precision slurries |
| US11385157B2 (en) | 2016-02-08 | 2022-07-12 | New York University | Holographic characterization of protein aggregates |
| US11747258B2 (en) | 2016-02-08 | 2023-09-05 | New York University | Holographic characterization of protein aggregates |
| US10670677B2 (en) | 2016-04-22 | 2020-06-02 | New York University | Multi-slice acceleration for magnetic resonance fingerprinting |
| US11543338B2 (en) | 2019-10-25 | 2023-01-03 | New York University | Holographic characterization of irregular particles |
| US11921023B2 (en) | 2019-10-25 | 2024-03-05 | New York University | Holographic characterization of irregular particles |
| US11948302B2 (en) | 2020-03-09 | 2024-04-02 | New York University | Automated holographic video microscopy assay |
Also Published As
| Publication number | Publication date |
|---|---|
| ATE17524T1 (en) | 1986-02-15 |
| JPS56130639A (en) | 1981-10-13 |
| EP0035437B1 (en) | 1986-01-15 |
| DE3173482D1 (en) | 1986-02-27 |
| JPH0237536B2 (en) | 1990-08-24 |
| FR2476839B1 (en) | 1982-12-17 |
| EP0035437A1 (en) | 1981-09-09 |
| FR2476839A1 (en) | 1981-08-28 |
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