Morphological characterization of particles by the intensity and polarization of the scattered radiation

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Optik

j o u r n a l h o m e p a g e :w w w . e l s e v i e r . d e / i j l e o

Original

research

article

Morphological

characterization

of

particles

by

the

intensity

and

polarization

of

the

scattered

radiation

H.

Chorfi

_,

_K.

_Ayadi

_,

_R.

_Gader

_,

_L.

_Boufendi

a_{AppliedOpticsLaboratory,InstituteofOpticsandPrecisionMechanicsSetif-1-University,19000Setif,Algeria} b_{GREMI,OrléansUniversity,14Rued’IssoudunBP6744,45067Orléanscedex2,France}

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o

Light-biologicaltissuesinteraction Complexindexofbiologicaltissues

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b

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Opticaltechniquesarebeingusedmoreandmore,becausetheyhavetheadvantageofbeing non-destructive,thelightscatteringbythematerialprovidesaframeworkofprospecting pointedandfast.Theelasticandinelasticinteractionportionofthelightwiththematter allowsfollowingtheassessmentofparticulatematterincludingcellnucleiwhicharethe focusoftissuepathologies.Ourworkfocusedontheuseofthisphenomenontofollowthe evaluationinsizeandshapeofthenuclei,inordertopreventtumoractivity.

©2017ElsevierGmbH.Allrightsreserved.

1. Introduction

Lightscatteredbythebiologicaltissueisratherrelatedtoitsstructure,includingtothedensity[1],size[2]andmorphology ofcellsnuclei[3],etc,theseimportantparametersareindicationsforthepathologisttomakedifferentiatebetweennormal cells(whichoftenhaveastructuredorganization),andtumorcells(whichpresentadisorderlystructure).

Inthepresentwork,thelightscatteringisusedasatooltocharacterizethiskindoftissue.Theadvantageofthistechnique isthatitismadewithoutcontactwiththeobjectstudied,non-destructiveandnon-ionizing.Thismeansthattheuseof electromagneticwaveinformationis nowthesubjectofincreasinginterest inthebiomedical field,andthephysicsof materials[4,5].Theprecisiononthediagnosisisrelatedtotheprecisiononthemeasurementsofthescatteredradiation,the parametersofwhichextractsmaybeexploitedtostudytheevolutionofthemicroparticlessizeandmorphology.Various measurementsofthescatteringintensities,andinparticularofitsangular,spectral,orpolarizationdependence,canserve asadiagnosticmeans.

Our objective istomake help pathologicalanatomy services.Thistechnique offersvaluableassistance byits non-destructiveeffectanditsspeedandprecision,byvaryingsameopticalparameterssuchaswavelength,polarizationstate andscatteringangle,theinformationontheevolutionofparticlessizesandmorphologymakesitpossibletopredictdirectly theexistenceofpathology.

∗ Correspondingauthor.

E-mail addresses: chorfihichem@univ-setif.dz, chorfihichemopa2@gmail.com (H. Chorfi), ayadi.khaled@hotmail.com (K. Ayadi),

romaissagader93@gmail.com(R.Gader),laifa.boufendi@univ-orleans.fr(L.Boufendi).

https://doi.org/10.1016/j.ijleo.2017.10.056

Theamplitudeofscatteredlightatdifferentanglesdependsnotonlyoncomplexrefractionindexofthemediuminwhich theparticleexistsandtheparticlesize[9],butalsoontheparticlemorphology[10,11].

Usingtheabovemethodforcalculationthescatteringphasefunctions,wecanexaminetheeffectsofparticlesize,shape, refractiveindexandparticlemorphology.Wefirstexaminetheeffectsofparticlesizeonthescatteringproperties.Weuse theMietheorytoplottheangularscatteringdistributionsforaseriesofradiusfrom0.1␮mto14.0␮mwhichhavebeen illuminatedwithseveralwavelengthsofpolarizedvisiblelight.

Takingintoaccountthepolarizationweusedthecomplexformulasofscattering[12,13].Theyinvolvetwocomplex functionsofscatteredamplitude:S1()andS2().

Theelectricfieldisdecomposedintotwopolarizations: ErPolarizedperpendicularelectricfieldtothescatteringplane.

EtPolarizedparallelelectricfieldtothescatteringplane.

Theexpressionofthediffusionis: Er=S1() e−ikr+ikz ikr Er0 (01) Et=S2() e−ikr+ikz ikr Et0 (02)

Er0andEt0areIncidentfields.

Foranunpolarizedincidentwave,theintensityisthen: I=I0

1

2r2_k2(i1+i2) (03)

IfthewaveislinearlypolarizedalongOx: I₌I0 1 r2_k2(i1sin 2_(ϕ) +i2cos2(ϕ)) (04) When:i1=|S1()|2andi2=|S2()|2

TheamplitudefunctionsS1(perpendiculartothescatteringplane)andS2 (paralleltothescatteringplane)havethe

followingform: S1()=





Theangularfactorsnandnhavethefollowingforms:

n(cos())= 1 sin()P 1 n(cos()) (07) n= d dP 1 n(cos()) (08)

Fig.1.Geometryusedtodescribetheincidentandscatteredfields.Weletthezaxisbethedirectionofpropagationoftheincidentlight,anddefinethe scatteringplaneasthatcontainingthezaxisandradiusvector.Wewritethescatteredfieldsintermsofadifferentbasisthanthatusedtodescribethe incidentfields.Eachofthesebasissetshasaunitvectorthatisparalleltoandaunitvectorthatisperpendiculartothescatteringplane[6].

Fig.2. Schemeoftheusedset-up.

4. Experimentalachievement

Tomeasurethescatteredintensityasafunctionoftheangleofobservation,weusedtheexperimentalsetupshownin thefigurebelow:

Theoutgoingbeamfromaxenonlightsourceiscollimatedbyusingtwolenses(lens1andlens2)forgettingaKöhler illumination.Forenhancingthebeam,afielddiaphragmandaspatialfilterareadded.Theobtainedbeamilluminatesthe samplesurfaceandahemisphericaldetectorisfinallyusedtodetectthescatteredintensitiesaccordingtotheangleof observation.Inthecaseofspectralandpolarizedlightapplications,apolarizerandachromaticfilterareinsertedbeforethe sampleposition(Figs.1and2).

Thepolarizedsignalscapturedareintegratedtoobtainthescatteredintensitywhichrelatesthesampleresponseusing anappropriateprogramunderMatlab-Clanguagesoftwarethatwehavedeveloped.

5. Cartesianrepresentationofintensities

Theobservationofthedifferentcurvesofthescatteredintensitiesasafunctionoftheangleofobservationandthe wavelengthgivesthesameappearanceforthedifferentcases.Nevertheless,weobservedifferentspecularintensitiesasa functionof␭,thisisexplainedbytheinfluenceoftheabsorptionparameterbythetissue.Infact,wenoticealessimportant lossforlongwavelengths.Fromthere,wewillusethelongestwavelengthtominimizetheeffectofabsorption(Tables1–4). Theresultsshowfluctuationsasafunctionofthepolarizationstateofthescatteredwave;thismayhelpustoevaluate anaveragemorphologyofthescatteringparticlesbycalculatingthediametersasafunctionofthepolarizationangle.

Forthecalculations,wehavedevelopedprogramstoplotthecurvesandtodeterminetheareas(theglobalintensities) ofthedifferentmeasurements,andthenonthebasisofthemathematicalmodelofMie,wehaveimprovedouralgorithm inordertoextractthemorphologiesfromthecalculatedparticlessizes.

Thefollowingtableshowssomeresultsobtained:

Byobservingtheresultsrepresentedinthetableabove,itisnotedthattheareasunderthecurvesofthescattered intensitiesinthecaseofthetumortissuearelargercomparedtothenormaltissue.Thepolarizationshowsasignificant differenceinthelevelofintensitysensedaccordingtothedifferentstates,thiscanbeexploitedtodeterminethespatial geometryofthediffuser(morphology).Wehaveconfirmedexperimentallythattheintensityofthescatteredlightisvery

30◦

60◦

Table1(Continued)

Polarizationangle(␤) NormalColon TumoralColon

120◦

150◦

180◦

Table2

RepresentationoftheareasofthecurvesfortheColonasafunctionoftheWavelengthandthepolarizationstate:(A)NormalColon,(B)TumorColon.

␤(◦) ␭=470nm ␭=510nm ␭=630nm Areas A B A B A B 0◦ _{0.6845 2.3383 1.0342 1.1509 0.9671 1.7345} 30◦ _{0.4135 1.7938 0.6184 1.2360 0.9556 1.7598} 60◦ 0.3149 2.1616 0.5836 1.2406 0.9641 2.1732 90◦ 0.2578 2.1927 0.6312 1.2556 0.9140 1.7686 120◦ _{0.3832 2.0513 0.8275 1.1094 0.9431 1.3235} 150◦ _{0.4185 0.9144 0.3088 1.1353 1.0072 1.9776} 180◦ _{0.5383 0.8161 0.2339 1.4989 0.9498 1.6517}

stronglydependentonseveralexperimentalparameterssuchasthewavelength,thepolarizationstateandtheparticlesize ofthescatteringmedium.

6. Measurementofnucleussizesusinglightscattering

Theefficiencyoflightscatteringpushedustodevelopacalculationprogramtodeterminetheparticlesizesfromthe collectedpolarizedintensities.ThisprogrambasedonMie’stheoryallowedustoobtainthesizesgatheredinthetable.The resultsobtainedwerecomparedwiththemicroscopicvalueswhichseemtobeingoodagreement.

150◦ 2.02 3.76

160◦ _{2.42 3.76}

170◦ _{2.18 3.72}

180◦ _{2.20 3.88}

Table4

Polarrepresentationofthemorphologyofthestudiednuclei.

Coreofanormalcell Coreofatumorcell

Colon

Bysimplifyingthesemeasurements,wecandeterminethesizeofthesupposedsphericalparticle: Theaveragecoresizeofanormalcell(Colon)is:3.02_␮m

Theaveragesizeofthetumorcell(colon)is:3.81␮m

Thedifferentdiametervaluescanbecollectedinapolarcoordinatesystemtoevaluatetheparticlemorphology.

7. Studyofmorphology

Amorphologicalstudybasedonthecorrelationofthesizesobtainedbyourprogramwascarriedout,theresultsmade itpossibletoevaluatethegeneralmorphologyofthenucleibyplottingthespatialdistributionofsizes.

Thestudyofthemorphologyofcellnucleishowsthedifferencebetweenthenormalandtumoralnucleus,thisdifference isveryclearbyobservingthetableabove.FortheColon,wecansaythatthemorphologyhasbeenmodifiedinvalueand form,infavorofabiologicalevolution,theevolutionofthesizeandmorphologyofnuclei(diffusingparticles)Canleadto theemergenceofapathologyoftissue.

8. Conclusion

Thespatialdistributionofthescatteredlightintensitydependsoncell’smorphologyandthepolarizationstatesofincident light;wecanextractcellularmorphologicalinformationfromthescatteredlightinspecificangularrangesortheoverall patterntodiscriminatedifferentcelltypes.

Theangularandspectralvariationsallowedustoevaluatethesizesofthenucleibetweenthenormalandpathological organ.Thepolarizationstateparametermadeitpossibletoevaluatethemorphologyofthetwocases.Theresultsobtained havebeenconfrontedwithmeasurementsbymicroscopyofthesesameparticles,andthecomparisonwasgivenasatisfaction withtheopticaltoolsetup.

Acknowledgments

“ThisworkwassupportedbytheMinistryofHigherEducationandScientificResearch(Ministèredel’Enseignement SupérieuretdelaRechercheScientifique,MESRS).Wewouldliketothanktheteamofthepathologicalanatomyservice− theuniversityhospitalofSetif,fortheirhelp."

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