ASTM E2228-10
(Guide)Standard Guide for Microscopic Examination of Textile Fibers
Standard Guide for Microscopic Examination of Textile Fibers
SIGNIFICANCE AND USE
Microscopical examination is one of the least destructive means of determining rapid and accurate microscopic characteristics and generic polymer type of textile fibers. Additionally, a point-by-point, side-by-side microscopic comparison provides the most discriminating method of determining if two or more fibers are consistent with originating from the same source. This guideline requires specific pieces of instrumentation outlined herein.
SCOPE
1.1 This section describes guidelines for microscopical examinations employed in forensic fiber characterization, identification, and comparison. Several types of light microscopes are used, including, stereobinocular, polarized light, comparison, fluorescence, and interference. In certain instances, the scanning electron microscope may yield additional information. Select which test(s) or techniques to use based upon the nature and extent of the fiber evidence.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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Designation: E2228 − 10
Standard Guide for
1
Microscopical Examination of Textile Fibers
This standard is issued under the fixed designation E2228; 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.
1. Scope absorbed by the fiber and selectively transmits only light of
greater wavelengths than the cut-off wavelength.
1.1 This section describes guidelines for microscopical
examinations employed in forensic fiber characterization,
3.2.3 Becke line—the bright halo near the boundary of a
identification, and comparison. Several types of light micro-
fiber that moves with respect to that boundary as the fiber is
scopes are used, including, stereobinocular, polarized light,
moved through best focus when the fiber is mounted in a
comparison, fluorescence, and interference. In certain
medium that differs from its refractive index.
instances, the scanning electron microscope may yield addi-
3.2.4 Becke line method—a method for determining the
tional information. Select which test(s) or techniques to use
refractiveindexofafiberrelativetoitsmountantbynotingthe
based upon the nature and extent of the fiber evidence.
direction in which the Becke line moves when the focus is
1.2 The values stated in SI units are to be regarded as
changed.
standard. No other units of measurement are included in this
3.2.4.1 Discussion—The Becke line will always move to-
standard.
ward the higher refractive index medium (fiber or mountant)
when the focal distance is increased and when the focal
2. Referenced Documents
distance is decreased away from the objective and will move
2
2.1 ASTM Standards:
toward the lower refractive index medium when the sample is
D123Terminology Relating to Textiles
moved toward the objective.
D276Test Methods for Identification of Fibers in Textiles
3.2.5 birefringence—the numerical difference in refractive
3
2.2 AATCC Standards:
indices for a fiber, given by the equation: ni− n'. Birefrin-
AATCC Test Method 20:QualitativeTest Method 20–2007
gence can be calculated by determining the retardation (r) and
Fiber Analysis: Qualitative
thickness (T) at a particular point in a fiber and by using the
equation:
3. Terminology
B 5 r ~nm!/1000T ~µm!
3.1 Definitions—For definitions of terms used in this guide,
3.2.6 comparison microscope—a system of two micro-
refer to Terminology D123.
scopes positioned side-by-side and connected via an optical
3.2 Definitions of Terms Specific to This Standard:
bridge in which two specimens may be examined simultane-
3.2.1 anisotropic—a characteristic of an object, which has
ously in either transmitted or reflected light.
opticalpropertiesthatdifferaccordingtothedirectioninwhich
3.2.7 compensator—any variety of optical devices that can
lighttravelsthroughtheobjectwhenviewedinpolarizedlight.
be placed in the light path of a polarizing microscope to
3.2.2 barrier filter—afilterusedinfluorescencemicroscopy
introduce fixed or variable retardation comparable with that
that suppresses unnecessary excitation light that has not been
exhibitedbythefiber;theretardationandsignofelongationof
the fiber may then be determined.
3.2.7.1 Discussion—Compensators may employ a fixed
1
This guide is under the jurisdiction of ASTM Committee E30 on Forensic
mineral plate of constant or varying thickness or a mineral
Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
platethatmayberotated,orhaveitsthicknessvariedbytilting
Current edition approved Sept. 15, 2010. Published October 2010. Originally
to alter the thickness presented to the optical path (and
approved in 2002. Last previous edition approved in 2002 as E2228–02. DOI:
10.1520/E2228-10.
retardation introduced) by a set amount.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.8 compensator, full wave (or red plate)—a compensator
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
usually a plate of gypsum, selenite or quartz, which introduces
the ASTM website.
a fixed retardation between 530 to 550nm (approximately the
3
Available from American Association of Textile Chemists and Colorists
retardation of the first order red color on the Michel-Levy
(AATCC), P.O. Box 12215, Research Triangle Park, NC 27709, http://
www.aatcc.org. chart).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E2228 − 10
3.2.9 compensator, quarter wave—a compensator, usually acid,andazo).Theyareincorporatedintothefiber
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E2228–02 Designation:E2228–10
Standard Guide for
1
Microscopical Examination of Textile Fibers
This standard is issued under the fixed designation E2228; 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.
1. Scope
1.1This section describes guidelines for microscopical examinations employed in forensic fiber characterization, identification,
and comparison. Several types of light microscopes are used including stereobinocular, polarized light, comparison, fluorescence
and interference. In certain instances, the scanning electron microscope may yield additional information. Select which test(s) or
techniques to use based upon the nature and extent of the fiber evidence.
1.1 Thissectiondescribesguidelinesformicroscopicalexaminationsemployedinforensicfibercharacterization,identification,
andcomparison.Severaltypesoflightmicroscopesareused,including,stereobinocular,polarizedlight,comparison,fluorescence,
and interference. In certain instances, the scanning electron microscope may yield additional information. Select which test(s) or
techniques to use based upon the nature and extent of the fiber evidence.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
2. Referenced Documents
2
2.1 ASTM Standards:
D276
D123 Terminology Relating to Textiles
D276 Test Methods for Identification of Fibers in Textiles
3
2.2 AATCC Standards:
AATCC Test Method 20:Qualitative Test Method 20–2007 Fiber Analysis: Qualitative
3. Terminology
3.1
3.1 Definitions—For definitions of terms used in this guide, refer to Terminology D123.
3.2 Definitions of Terms Specific to This Standard:
3.1.1
3.2.1 anisotropic—acharacteristicofanobject,whichhasopticalpropertiesthatdifferaccordingtothedirectioninwhichlight
travels through the object when viewed in polarized light.
3.1.2
3.2.2 barrier filter—a filter used in fluorescence microscopy that suppresses unnecessary excitation light that has not been
absorbed by the fiber and selectively transmits only light of greater wavelengths than the cut-off wavelength.
3.1.3
3.2.3 Becke line—the bright halo near the boundary of a fiber that moves with respect to that boundary as the fiber is moved
through best focus when the fiber is mounted in a medium that differs from its refractive index.
3.1.4
3.2.4 Beckelinemethod—amethodfordeterminingtherefractiveindexofafiberrelativetoitsmountantbynotingthedirection
in which the Becke line moves when the focus is changed.
3.2.4.1 Discussion—TheBeckelinewillalwaysmovetowardthehigherrefractiveindexmedium(fiberormountant)whenthe
focal distance is increased and when the focal distance is decreased away from the objective and will move toward the lower
refractive index medium when the sample is moved toward the objective.
1
This guide is under the jurisdiction of ASTM Committee E30 on Forensic Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
Current edition approved August 10, 2002. Published October 2002. DOI: 10.1520/E2228-02.
Current edition approved Sept. 15, 2010. Published October 2010. Originally approved in 2002. Last previous edition approved in 2002 as E2228–02. DOI:
10.1520/E2228-10.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book ofASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The boldface numbers in parentheses refer to the list of references at the end of this standard.
3
Available from American Association of Textile Chemists and Colorists (AATCC), P.O. Box 12215, Research Triangle Park, NC 27709, http://www.aatcc.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E2228–10
3.1.53.2.5 birefringence—the numerical difference in refractive indices for a fiber, given by the formula:equation: n{− n'.
Birefringence can be calculated by determining the retardation (r) and thickness (T) at a particular point in a fiber and by using
the formula: B=r (nm)/1000T (µm).
3.1.6) at a particular point in a fiber and by using the equation:
B 5 r ~nm!/1000T ~µm!
3.2.6 comparison microscope—a system of two microscopes positioned side-by-side and
...
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