ASTM E1458-12(2022)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:E1458 −12 (Reapproved 2022)
Standard Test Method for
Calibration Verification of Laser Diffraction Particle Sizing
Instruments Using Photomask Reticles
This standard is issued under the fixed designation E1458; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
There exists a large variety of techniques and instruments for the sizing of particles and droplets in
fluid suspension. These instruments are based on a number of different physical phenomena and
interlaboratory comparisons of data on, for example, reference liquid sprays have shown significant
variability. This test method evolved in conjunction with efforts to explain the observed variability.
Theeffectivenessofthistestmethodcanbetracedtothefactitcircumventsdifficultiesassociatedwith
producing, replicating, and maintaining a standard sample of liquid particles in a spray. This test
method uses a photomask reticle to provide a simulation of some of the optical properties of a
referencepopulationofsphericalparticles.Thistestmethodisonlyapplicabletoopticalparticlesizing
instruments that are based on measurement and analysis of light scattered in the forward direction by
particles illuminated by a light beam. Since modern optical instruments generally use a laser to
produce a light beam, and since the light scattered in the forward direction by particles can often be
accurately described using diffraction theory approximations, the class of instruments for which this
test method applies have become generally known as laser diffraction particle sizing instruments.
2,3
Because it is specifically Fraunhofer diffraction theory that is used in the approximation, these
instruments are also known as Fraunhofer diffraction particle sizing instruments.
The diffraction approximation to the general problem of electromagnetic wave scattering by
particles is strictly valid only if three conditions are satisfied. The conditions are: particle sizes must
be significantly larger than the optical wavelength, particle refractive indices must be significantly
different than the surrounding medium, and only very small (near-forward) scattering angles are
considered. For the case of spherical particles with sizes on the order of the wavelength or for large
2,3
scattering angles, the complete Lorenz-Mie scattering theory rather than the Fraunhofer diffraction
approximation must be used. If the size and angle constraints are satisfied but the particle refractive
index is very close to that of the medium, the anomalous diffraction approximation may be used.
A complication is introduced by the fact that the optical systems of most laser diffraction particle
sizing instruments can be used, with only minor modifications such as changing a lens or translating
the sample, for measurement configurations outside the particle size or scattering angle range for
which the diffraction approximation is valid. In this situation the scattering inversion software in the
instrumentwouldgenerallyincorporateascatteringmodelotherthanFraunhoferdiffractiontheory,in
whichcasetheterm“laserdiffractioninstrument”mightbeconsideredamisnomer.However,suchan
instrumentisstillinessencealaserdiffractioninstrument,modifiedtodecreasethelowerparticlesize
limit.Acalibration verification procedure as described by this test method would be applicable to all
instrumentconfigurations(oroperationalmodes)wherethephotomaskreticleaccuratelysimulatesthe
relevant optical properties of the particles.
The ideal calibration test samples for laser diffraction particle sizing instruments would be
comprised of the actual particle or droplet material of interest in the actual environment of interest
with size distributions closely approximating those encountered in practice. However, the use of such
calibration test samples is not currently feasible because multi-phase mixtures may undergo changes
during a test and because actual samples (for example, a spray) are not easily collected and stabilized
for long periods of time. The subject of this test method is an alternative calibration test sample
comprised of a two-dimensional array of thin, opaque circular discs (particle artifacts) deposited on
a transparent substrate (the photographic negative, that is, clear apertures in an opaque substrate, may
beusedaswell).Eachdiscorparticleartifactrepresentstheorthogonalprojectionofthecross-section
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1458−12 (2022)
of one member of a population of spherical particles comprising the reference population. The
collectionofparticleartifactsonareticlerepresentsanorthogonalprojectionofalltheparticlesinthe
reference population for one particular three-dimensional arrangement of the population where the
member particles are positioned within a finite reference volume. The reference volume is generally
defined such that the area covered by particle artifacts on the reticle is roughly equivalent to the
cross-section of the instrument light beam. The reference population would generally contain a large
number of particles, with a size distribution that approximates distributions of practical interest,
randomly distributed over the reference volume. Large numbers and random positions minimize
complications that can arise from optical coherence effects (interference).
Of importance here is the fact that the near-forward scattering characteristics of the orthogonal
projections of the particle cross-sections onto the reticle plane accurately simulate, in regimes where
the diffraction approximation is valid, the near-forward scattering characteristics of the reference
population (independent of the chemical composition of the particles in the reference population). In
otherwordsthephotomaskreticle,whenilluminatedwithalaserbeamofknownproperties,generates
a reference scattered light signature which can be predicted analytically from a knowledge of the size
distribution of the reference population. The properties of the reference population can be inferred
from a characterization (using optical microscopy) of the sizes of the particle artifacts on the reticle.
As the instrument is operated away from the diffraction regime, the scattering properties of the
photomask reticle diverge from that which would be produced by the reference population and
interpretation of the measurements becomes more problematic.
The most complete test result for this test method would be a discrete size distribution reported for
averylargenumberofsizeclassintervals,butintercomparisonsofsuchdistributionsaredifficult.For
that reason statistical parameters (for example, representative diameters and measures of the
dispersion) of the particle size distribution are used. Two examples of statistical parameters are the
volumemediandiameter D andtherelativespan(D − D )/D asdefinedinPracticeE799
V0.5 V0.9 V0.1 V0.5
(recall that volume parameters such as D for a photomask reticle are defined in the sense that
Vf
two-dimensionalparticleartifactsscatterlightlikesphericalparticlesofthesamediameter).Estimates
of the true values of these statistical parameters for a photomask reticle (or more precisely the true
values for the reference population simulated by the reticle) can be established using optical or
electron microscope measurements of the diameters of the particle artifacts on the reticle. The values
so established are termed image-analysis reference values and will be used herein as the accepted
reference values. It is the stability of D , the relative span, and all other statistical parameters
V0.5
representative of the particle artifact size distribution for a reticle and the ability to produce nearly
identical replicate copies of the reticles that make this test method useful. A comparison of the
accepted reference value of D , the relative span, or any other parameter of a reticle with a
V0.5
corresponding test result from the instrument under evaluation can be used to assess the acceptability
of the instrument and of the data routinely obtained with the instrument.
This test method is under the jurisdiction ofASTM Committee E29 on Particle and Spray Characterization and is the direct responsibility of Subcommittee E29.02 on
Non-Sieving Methods.
Current edition approved Feb. 1, 2022. Published April 2022. Originally approved in 1992. Last previous edition approved in 2016 as E1458 – 12 (2016). DOI:
10.1520/E1458-12R22.
Bohren, C.F., and Huffman, D.R., Absorption and Scattering of Light by Small Particles, John Wiley and Sons, New York, 1983.
van de Hulst, H.C., Light Scattering by Small Particles, Dover Publications Inc., New York, 1981.
1. Scope modeled by the instrument data processing and data reduction
software. The precision and bias limits presented herein are,
1.1 This test method describes a procedure necessary to
therefore, estimates of the instrument performance under ideal
permit a user to easily verify that a laser diffraction particle
conditions. Nonideal factors that could be present in actual
sizing instrument is operating within tolerance limit
applicationsandthatcouldsignificantlyincreasethebiaserrors
specifications, for example, such that the instrument accuracy 4
of laser diffraction instruments include vignetting (that is,
is as stated by the manufacturer.The recommended calibration
wherelightscatteredatlargeanglesbyparticlesfarawayfrom
verification method provides a decisive indication of the
the receiving lens does not pass through the receiving lens and
overall performance of the instrument at the calibration point
therefore does not reach the detector plane), the presence of
or points, but it is specifically not to be inferred that all factors
ininstrumentperformanceareverified.Ineffect,useofthistest
methodwillverifytheinstrumentperformanceforapplications
Hirleman, E.D., Oechsle, V., and Chigier, N.A., “Response Characteristics of
involving spherical particles of known refractive index where
Laser Diffraction Particle Sizing Systems: Optical Sample Volume and Lens
the near-forward light scattering properties are accurately Effects,” Optical Engineering, Vol 23, 1984, pp. 610–619.
E1458−12 (2022)
nonspherical particles, the presence of particles of unknown E799Practice for Determining Data Criteria and Processing
refractive index, and multiple scattering. for Liquid Drop Size Analysis
E1187Terminology Relating to Conformity Assessment
1.2 Thistestmethodshallbeusedasasignificanttestofthe
(Withdrawn 2006)
instrument performance. While the procedure is not designed
2.2 Military Standard:
for extensive calibration adjustment of an instrument, it shall
MIL-STD-45662Calibration Systems Requirements
beusedtoverifyquantitativeperformanceonanongoingbasis,
2.3 NIST Standard:
to compare one instrument performance with that of another,
NIST SP 676-1Measurement Assurance Programs
and to provide error limits for instruments tested.
2.4 ANSI Standard:
1.3 This test method provides an indirect measurement of
ANSI-ASQC Z-1Standard for Calibration Systems
some of the important parameters controlling the results in
2.5 ISO Standard:
particle sizing by laser diffraction. A determination of all
ISO Guide 2AGeneral Terms and Their Definitions Con-
parameters affecting instrument performance would come
cerning Standardization Certification, and Testing Lab.
under a calibration adjustment procedure.
Accreditation
1.4 This test method shall be performed on a periodic and
3. Terminology
regular basis, the frequency of which depends on the physical
environment in which the instrumentation is used. Thus, units 3.1 Current ASTM Standard Definitions—Definitions of the
terms listed below, as used in this test method are from the
handled roughly or used under adverse conditions (for
Compilation of ASTM Standard Definitions:
example, exposed to dust, chemical vapors, vibration, or
3.1.1 accuracy—see Terminology D123, (Committee D13).
combinations thereof) shall undergo a calibration verification
more frequently than those not exposed to such conditions.
3.1.2 assignable cause—see Terminology E456, (Commit-
This procedure shall be performed after any significant repairs
tee E11).
are made on an instrument, such as those involving the optics,
3.1.3 bias—see Terminology D123, (Committee D13).
detector, or electronics.
3.1.4 calibration—see Terminology E1187, (Committee
1.5 The values stated in SI units are to be regarded as
E36).
standard. No other units of measurement are included in this
3.1.5 Discussion—This and many other commonly used
standard.
definitions for calibration are very broad in the sense that they
1.6 This standard does not purport to address all of the
could encompass a wide range of tasks. (See for example
safety problems, if any, associated with its use. It is the
MIL-STD-45662, NISTSP676-1, andANSI-ASQC Z-1 Draft
responsibility of the user of this standard to establish appro-
StandardforCalibrationSystems).Forexample,insomecases
priate safety, health, and environmental practices and deter-
calibration is only the determination of whether or not an
mine the applicability of regulatory limitations prior to use.
instrument is operating within accuracy specifications (toler-
1.7 This international standard was developed in accor-
ance testing in NIST SP 676-1). In other cases calibration
dance with internationally recognized principles on standard-
includes reporting of differences between the instrument re-
ization established in the Decision on Principles for the
sponse and the accepted value of the standard, for example, to
Development of International Standards, Guides and Recom-
produce a “Table of Corrections” to be used with the instru-
mendations issued by the World Trade Organization Technical
ment. Finally, calibration can also include any repairs or
Barriers to Trade (TBT) Committee.
adjustments required to make the instrument response consis-
tentwiththestandardwithinthestatedaccuracyspecifications.
2. Referenced Documents
To clarify the situation it is proposed that the more specific
2.1 ASTM Standards:
terms calibration verification and calibration adjustment (see
A340Terminology of Symbols and Definitions Relating to
3.4) both of which would fall under these broad definitions of
Magnetic Testing
calibration.
D123Terminology Relating to Textiles
3.1.6 coeffıcient of variation—see Terminology D123,
D3244Practice for Utilization of Test Data to Determine
(Committee D13).Also known as the relative standard devia-
Conformance with Specifications
tion (see Terminology E135, Committee E01).
E131Terminology Relating to Molecular Spectroscopy
E135Terminology Relating to Analytical Chemistry for
The last approved version of this historical standard is referenced on
Metals, Ores, and Related Materials
www.astm.org.
E284Terminology of Appearance 7
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
E456Terminology Relating to Quality and Statistics Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
dodssp.daps.dla.mil.
E691Practice for Conducting an Interlaboratory Study to
Available from National Institute of Standards and Technology (NIST), 100
Determine the Precision of a Test Method
Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from International Organization for Standardization (ISO), 1, ch. de
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org.
Standards volume information, refer to the standard’s Document Summary page on Compilation of ASTM Standard Definitions, 7th edition,ASTM International,
the ASTM website. Philadelphia, 1990.
E1458−12 (2022)
3.1.7 reference material—see Terminology E1187, (Com- resultobtainedbyadifferentoperatorwitheachoperatorusing
mittee E36) (see ISO Guide 2A). one apparatus to obtain the same number of observations over
theshortestpracticaltimeinterval.(DerivativeofTerminology
3.1.8 scattering—seeTerminology E284, (Committee E12).
D123, Committee D13.)
3.1.9 standard reference material—see Terminology E131,
3.2.7 repeatability, repeatability limit—see Terminology
(Committee E13).
E456, (Committee E11).
3.1.10 test method, n—see Terminology D123, (Committee
3.2.8 reproducibility, reproducibility limit—see Terminol-
D13).
ogy E456, (Committee E11).
3.1.11 test method equation—see Terminology D123,
3.3 Definitions From Other Sources:
(Committee D13).
3.3.1 calibration—comparison of a measurement standard
3.1.12 test result—see Terminology D123, (Committee
or instrument of known accuracy with another standard or
D13).
instrument to detect, correlate, report, or eliminate by
3.1.13 tolerance limits, specification or calibration—see
adjustment, any variation in the accuracy of the item being
Terminology A340, (Committee A06).
compared. (See MIL-STD-45662.)
3.1.14 verification—see Terminology E135, (Committee
3.4 Definitions Established in This Test Method:
E01).
3.4.1 calibration adjustment, for instruments—the process
3.2 OtherASTMDefinitions—Definitionsofthetermsgiven of adjusting any of the various sensitivity settings or param-
below are either close derivatives of definitions in the Compi- eters of an instrument to restore the instrument performance to
lation of ASTM Standard Definitions, or are given inASTM within tolerance limit specifications.
Standards approved after that time.
3.4.2 calibration verification, for instruments—the process
3.2.1 accepted reference value—a value that serves as an
of comparing the response of an instrument or a subsystem of
agreed-upon reference for comparison, and that is derived as:
an instrument to the accepted value of a standard of greater
(1) a theoretical or established value, based on scientific
accuracy (less uncertainty) for the purpose of evaluating the
principles, (2) an assigned value, based on experimental work
performance of the instrument with respect to stated precision
of some national or international organization such as the U.S.
and bias specifications.
National Institute of Standards and Technology (or its prede-
3.4.3 Discussion—The failure of an instrument to indicate
cessor the National Bureau of Standards), or (3) a consensus
the value of a standard to within the stated uncertainties of the
value, based on collaborative experimental work under the
instrument and standard would suggest corrective action, such
auspicesofascientificorengineeringgroup.(SeeTerminology
as a calibration adjustment.
E456.)
3.4.4 image-analysis reference value (for a photomask
3.2.2 D —a diameter such that the fraction, f, of the total
vf
reticle)—a reference value for a test result derived from
volume of particles contains precisely all of the particles of
theoretical calculations based on measurements of the sizes of
smaller diameter. (Derivative of that in Practice E799.)
particle artifacts on the reticle.
3.2.3 precision, n, general—see Terminology D123, (Com-
3.4.5 reference population (for a photomask reticle)—a
mittee D13).
finite population of particles of specified sizes for which a
3.2.4 precision, n, single-operator—the single-operator-
photomask reticle represents an orthogonal projection of one
laboratory-sample-apparatus-day precision of a method; the
particular three dimensional arrangement of the population.
precision of a set of statistically independent test results all
3.4.6 Discussion—Since there are many possible ways to
obtained as directed in the method and obtained over the
distributeafiniteparticlepopulationoverafinitevolume,there
shortest practical time interval in one laboratory by a single
are likewise many different photomask reticle configurations
operator using one apparatus. (Derivative of Terminology
that can represent a given reference population.
D123, Committee D13.)
3.4.7 reference volume (for a photomask reticle)—the
3.2.5 precision, between laboratory—the multi-laboratory,
hypothetical, finite volume within which the reference popu-
single-sample, single-operator-apparatus-day (within-
lation of particles represented by the reticle are placed.
laboratory) precision of a test method; the precision of a set of
3.4.8 true value (for a photomask reticle)—a value corre-
statistically independent test results all of which are obtained
sponding to a property of the reference population.
by testing the same sample of material and each of which is
obtained in a different laboratory by one operator using one
4. Significance and Use
apparatus to obtain the same number of observations over the
shortest practical time interval. (Derivative of Terminology
4.1 This test method permits a user to compare the perfor-
D123, Committee D13.)
mance of an instrument to the tolerance limit specifications
3.2.6 precision, within-laboratory (multi-operator)—the stated by a manufacturer and to verify that an instrument is
multi-operator, single-laboratory-sample, single-apparatusday suitable for continued routine use. It also provides for genera-
(within operator) precision of a test method; the precision of a tion of calibration data on a periodic basis, forming a database
set of statistically independent test results all obtained in one from which any changes in the performance of the instrument
laboratory using a single sample of material and with each test will be evident.
E1458−12 (2022)
4.2 This test method for the calibration verification of laser 5.2.2 Particle Artifacts—A photomask reticle shall have a
diffractionparticlesizinginstrumentsissuitableforacceptance number of thin circular discs (particle artifacts) deposited on a
testing of laser diffraction instruments so long as current substrate.
estimates of the bias (see Section 11) and the between- 5.2.3 Clear or Background Area—Aphotomaskreticleshall
laboratory precision of the test method (see Section 10) are have an area at least as large as the laser beam used by the
acceptably small relative to typical laser diffraction instrument instrumentthatisfreefromparticleartifacts.Thisregionofthe
accuracy specifications; see Practice D3244. photomask reticle is used for the background measurement to
zero the detectors.
5. Apparatus 5.2.4 Substrate—The reticle substrate shall be of optical
quality since it is used in a transmission mode. Antireflection
5.1 Laser Diffraction Instrument:
coatingswillminimizethepossibilityofspuriousreadingsdue
5.1.1 Discussion—Alaser diffraction particle sizing appara-
to reflections from the reticle reaching the detectors.
tus generally consists of a laser source to produce a beam of
5.3 Accepted Reference Values for a Photomask Reticle:
light, optical means for producing a suitable beam that passes
5.3.1 Discussion—In order to verify the performance of an
through a region of the particle field, means for detecting the
instrument in an absolute sense it is necessary to calculate the
laser energy scattered by the particles into a multiplicity of
bias of the instrument, that is, the difference between a
collectionangles,andmeansfortransformingtheobservations
measured value and the true value that for this test method
into statistical estimates of particle size distribution character-
correspondstothereferencepopulation.Althoughaphotomask
istics. In obtaining particle size calibration verification data
reticle is only a projection of the reference particle population,
using this test method, the analyst shall select the proper
imageanalysisofthearrayofparticleartifactsonaphotomask
instrument operating conditions to realize satisfactory instru-
reticle combined with information on the design of the reticle
ment performance. Operating conditions for individual instru-
can provide good estimates of the true values for the reference
ments are best obtained from the operation manuals provided
particle population. Reference values so obtained are termed
by the manufacturer because of variations in instrument
image-analysisreferencevalues.Sinceitmaybeimpracticalto
designs.
measure the sizes of thousands of particle artifacts, only a
5.2 Photomask Reticle:
representative sample of measurements may be available.
However, estimates based on an incomplete sample would
5.2.1 Discussion—Therearetypicallythousandsofparticles
have uncertainty resulting from bias and precision errors in
or droplets in the optical sample volume of a laser diffraction
measurements of the size of the individual particle artifacts,
particle sizing instrument during a measurement period. These
and also from uncertainties in inferring properties of the entire
large numbers are the result of the relatively large (line-of-
population of particle artifacts from the sample, that is,
sight) optical sample volume and are necessary to ensure
statistical sampling errors.
adequate statistical sampling of the distribution and to mini-
5.3.1.1 Further uncertainty results from the fact that an
mize coherent scattering effects. A photomask reticle is de-
orthogonal projection of a three-dimensional arrangement of
signed to simulate the near-forward scattering properties of a
randomly-positioned spherical particles will generally result in
specified, finite population of spherical particles (the reference
overlapping images. The image analysis method used to
population) randomly distributed within a hypothetical finite
characterize overlapped (and thus noncircular) images may
volume (the reference volume). The photomask reticle repre-
produce different results than the scattering mechanism.
sents an orthogonal projection of the cross-sections of all the
5.3.2 Specification of Accepted Reference Value:
sphericalparticlesinthereferencepopulationontoaplane.The
5.3.2.1 The procedure used to determine the accepted ref-
projectedareaofthereferencevolume,thatis,theareacovered
erence value for a photomask reticle used in this test method
by particle artifacts on the reticle, is normally approximately
equivalent to the cross-section of the instrument light beam. shall be specified. If the accepted reference value is based on
image-analysis the following shall be specified:
The reference population generally contains a large number of
particleswithasizedistributionthatapproximatesdistributions 5.3.2.2 Size Values for Nonoverlapping (Circular)
Artifacts—The method for assigning a size to nonoverlapping
of practical interest. (Large numbers and random positions are
necessary to ensure that the scattering contributions from the (circular) artifacts shall be specified. One possible measure of
sizeisthemaximumchordinsomepreferreddirection(thatis,
individual particle artifacts sum incoherently.)
the Ferret diameter).
5.2.1.1 A perfect simulation of a real particle or droplet
5.3.2.3 Size Values for Overlapping (Noncircular)
system would require a continuous distribution of particle
Artifacts—The method for assigning a size to overlapping
sizes, but multiple replications of a limited number of discrete
(noncircular)artifactsshallbespecified.Additionaluncertainty
particle sizes (primary particle sizes) may be used to approxi-
is introduced in the process of assigning a size to a nonspheri-
mate an actual size distribution on photomask reticles. The
cal or noncircular artifact, as there are many possible ap-
number of replications of the various primary sizes of the
proaches.
particle artifacts is specified in order to provide a discrete
approximation to the desired size distribution of particles or
droplets. The photomask reticle used in the ILS for this test
method had 23 discrete primary sizes with from one to several
Allen,T., Particle Size Measurement,4thedition,ChapmanandHall,London,
thousand replications of these sizes. 1990.
E1458−12 (2022)
5.3.2.4 Statistical Sampling—If only a subset of the particle 7.1.2 The necessarily finite resolution of particle sizing
artifacts on the reticle were measured and the sizes of the instruments requires that the measured size distribution either
remaining members of the particle population were inferred be represented as a discrete histogram of frequency for a finite
statistically,thentheprocedureshallbespecified.Forexample, number of size class intervals, or be specified by a small
sizes for unmeasured particle artifacts might be determined number of parameters (say two to four) of an analytic or
based on the assumption of a Gaussian within-primary-size- parametricsizedistributionfunction.Forthatreasonanimpor-
class distribution function. tant aspect of a laser diffraction measurement is the computa-
5.3.2.5 Calculating Representative Diameters—Calculation tional procedure used to obtain test results from the actual
ofrepresentativediameters D usingimage-analysisdatashall observations.
vf
be performed according to Practice E799.
7.2 Test Observations—The test observations consist of the
following two parts:
6. Reference to This Calibration Procedure
7.2.1 The set of measured scattered energy levels over a
6.1 Reference to this practice in documents relating to a
range of discrete scattering angles, and
laser diffraction particle sizing instrument shall constitute due
7.2.2 The measured optical extinction (that is equal to 1-T
notification that the adequacy of instrument performance has
where T is transmittance or the fraction of the laser energy
been evaluated by means of this test method. Performance is
beam transmitted directly through the medium).
considered to be adequate when test results are in agreement
7.3 Test Determinations—Thetestdeterminationsconsistof
with the accepted reference value of the photomask reticle
either of the following (7.3.1 is preferred over 7.3.2):
taking into account, according to Practice D3244, the repeat-
7.3.1 A discrete histogram of particle quantity (number,
ability and reproducibility limits of this test method given in
area, or volume) in a finite number of discrete size class
Section 10.
intervals, or
NOTE 1—A successful calibration verification using this test method
7.3.2 Theparametersspecifyingananalyticsizedistribution
will not ensure that all data obtained with the instrument will be
function(forexample,theRosin-Rammlerdistributionorother
meaningful. Data obtained while operating an instrument outside the
analytic functions discussed in Practice E799).
prescribed operating parameters may be invalid. For example, data
obtained from measurements in optically dense aerosols where no
7.4 Test Result—Atestresultforthistestmethodconsistsof
correctionformultiplescatteringhasbeenmadewillgenerallybeinvalid.
the following statistical parameters representative of the par-
ticle size distribution function:
7. Test Observations, Test Determinations, and Test
7.4.1 Thevolumemediandiameter D definedinPractice
Results
V0.5
E799, and
7.1 Discussion—Specifying a test result for a particle size
7.4.2 The relative span (volume basis) given by
distribution measurement is more complicated than for many
(D − D )/D as defined in Practice E799.
V0.1 0.5
V0.9
testmethodswhereonlyasingleparameter(forexample,mass,
7.4.3 All test determinations and calculations of all test
length) is desired. A particle size distribution function is, in
results must be consistent with Practice E799.
general, a continuous function but no practical measurement
system has infinite resolution as required to measure a
8. Procedure
complete, continuous distribution. Further, a general size
distribution function is particle frequency versus particle 8.1 Discussion—In a test method to verify the state of
diameter, but there are several measures of particle population calibration of an instrument there are only two possible
frequencies of interest depending on the application. For conclusions, either the instrument is operating within specified
example, while the number distribution is commonly used, the tolera
...