HomeGeneralResourcesMaterialPropertiesTablesUTTransducerCharacteristicsThesoundfieldofanultrasonictransduceroperatingatasinglefrequencyisdividedintoanearfieldandafarfieldzone.ThetransitionbetweenthesezonesoccursatadistanceYo+(orN)andissometimesreferredtoasthe"naturalfocus"ofaflat(ofunfocused)transducer.Thenear/fardistanceYo+issignificantbecauseamplitudevariationsthatcharacterizethenearfield(andcanmakeflawevaluationdifficult)changetoasmoothlydecliningamplitudeasthedistancefromthetransducerincreases.Thetablespresentedhereforunfocusedandfocusedultrasonictransducersrepresentsarangeoftypicaltransducers.Animportantcolumnintheunfocusedtables,NormalRangeofFocusing,showsthenormalrangeoffocusingforimmersiontransducersinwaterforbothsphericalandcylindricallenses.TheDownFieldFocalZonecolumnshowsthestartandendoftheYo+maximaonthetransduceraxisasthedistancefromthetransducerincreases.Sphericalorcylindricalfocusingchangesthestructureofthetransducerfieldby"pulling"theYo+pointnearerthetransducer,tothefocalpointofthetransducer.Again,theDownFieldFocalZonecolumnshowsthebeginningandendofthefocalzone,wheretheamplitudefalls6dBbelowthemaximaatthefocalpoint.ItisimportanttonotethatthedrivingexcitationnormallyusedinNDTapplicationsareeitherspikeorrectangularpulsars,notsinglefrequency.Theycansignificantlyaltertheresultsshowninbothtables.Nonetheless,thesupportinganalysisiswidelyusedbecauseitrepresentsareasonableapproximationandagoodstartingpoint.UnfocusedFrequency(MHz)Diameter(in.)FocalLength(in)6dBSpotSize(in)START(in)END(in)FocalGainSPHER.(dB)CYL.(in)1.00 1.00 2.50 .146 1.9 4.10 11.80 9.3 2.25 .500 1.50 .078 1.10 2.50 10.00 7.52.25 .750 2.00 .069 1.50 2.80 24.00 21.52.25 .750 3.00 .104 2.20 4.90 13.30 1.82.25 1.000 3.00 .078 2.30 3.90 27.90 25.42.25 1.000 5.00 .130 3.80 7.90 15.00 12.5 5.00 .250 .75 .035 .60 1.20 12.90 10.45.00 .375 1.00 .031 .80 1.30 26.50 24.05.00 .375 2.00 .062 1.50 3.50 8.30 5.85.00 .500 1.50 .035 1.20 1.90 30.20 27.75.00 .500 3.00 .070 2.20 4.90 12.90 1.45.00 .750 2.00 .031 1.60 2.20 39.20 36.75.00 .750 4.00 .062 3.10 5.40 40 24.05.00 .750 6.00 .094 4.60 9.40 16.20 13.75.00 1.000 3.00 .035 2.50 3.30 41.40 38.95.00 1.000 4.00 .047 3.20 4.60 37.50 35.05.00 1.000 6.00 .070 4.70 7.60 3.20 27.7 10.00 .125 .38 .018 .30 .60 12.90 10.410.00 .250 .75 .018 .60 1.00 30.20 27.710.00 .250 1.50 .035 1.10 2.40 12.90 10.410.00 .375 1.00 .016 .80 1.10 39.20 36.710.00 .375 2.00 .031 1.50 2.70 26.50 24.010.00 .375 3.00 .047 2.30 4.70 16.20 13.710.00 .500 1.50 .018 1.20 1.60 41.40 38.910.00 .500 3.00 .035 2.30 3.80 30.20 27.710.00 .500 5.00 .059 3.80 7.60 17.90 15.410.00 .750 3.00 .023 2.50 3.20 42.80 40.310.00 .750 4.00 .031 3.20 4.50 39.20 36.710.00 .750 6.00 .047 4.70 7.40 32.50 30.0 15.00 .125 .50 .016 .40 .80 16.20 13.715.00 .250 .75 .012 .60 .90 37.50 35.015.00 .250 1.50 .023 1.20 2.10 23.70 21.215.00 .375 1.50 .016 1.20 1.70 39.20 36.715.00 .375 2.50 .026 2.00 3.20 30.40 27.915.00 .375 4.00 .042 3.10 6.00 19.30 16.8 20.00 .125 .50 .012 .40 .70 23.70 21.220.00 .125 .75 .018 .60 1.20 12.90 10.420.00 .250 .75 .009 .60 .80 41.40 38.920.00 .250 1.50 .018 1.20 1.90 3.20 27.720.00 .250 3.00 .035 2.20 4.90 12.90 10.4FocusedTransducersFreq.(MHz)Dia.(in)Diameter/wavelengthBeamSpread(Degrees)6dBSpotSizeatYo+(in)NearFieldYo+(in)NormalRangeofFocusingMin&/Max(in)DownFieldFocalZoneStart&End(6dB)(in).50 .750 6.410 8.947 .188 1.202Yo+Yo+.719 2.322.50 1.000 8.547 6.707 .250 2.137Yo+Yo+1.279 4.1281.00 .750 12.821 4.470 .188 2.404 1.619 1.923 1.438 4.6441.00 1.000 17.094 3.352 .250 4.274 2.158 3.419 2.557 8.2552.25 .250 9.615 5.961 .063 .601Yo+Yo+.360 1.1612.25 .375 14.423 3.973 .094 1.352 .809 1.082 .809 2.6122.25 .500 19.231 2.980 .125 2.404 1.079 1.9923 1.438 4.6442.25 .750 28.846 1.986 .188 5.409 1.619 4.327 3.237 10.4482.25 1.000 38.462 1.490 .250 9.615 2.158 7.692 5.754 18.5745.00 .250 21.368 2.682 .063 1.335 .540 1.068 .799 2.5805.00 .375 32.051 1.788 .094 3.005 .809 2.404 1.798 5.8045.00 .500 42.735 1.341 .125 5.342 1.079 4.274 3.197 10.3195.00 .750 64.103 .894 .188 12.019 1.619 9.615 7.192 23.2185.00 1.000 85.470 .670 .250 21.368 2.158 17.094 12.786 41.27610.00 .125 21.368 2.682 .031 .668 .270 .534 .400 1.29010.00 .250 42.735 1.341 .063 2.671 .540 2.137 1.598 5.16010.00 .375 64.103 .894 .094 6.010 .809 4.808 3596 11.60910.00 .500 85.470 .670 .125 10.684 1.079 8.547 6.393 20.63810.00 .750 128.205 .447 .188 24.038 1.619 19.231 14.385 46.43610.00 1.000 170.940 .335 .250 42.735 2.158 34.188 25.573 82.55315.00 .125 32.051 1.788 .031 1.002 .270 .801 .599 1.93515.00 .250 64.103 .894 .063 4.006 .540 3.205 2.397 7.73915.00 .375 96.154 .596 .094 9.014 .809 7.212 5.394 17.41320.00 .125 42.735 1.341 .031 1.335 .270 1.068 .799 2.58020.00 .250 85.470 .670 .063 5.342 .540 4.274 3.197 10.319DatacompiledbyXactexCorporation.Sourcesoforiginaldataareunknown.