ASTM E175-82(2010)
(Terminology)Standard Terminology of Microscopy (Withdrawn 2019)
Standard Terminology of Microscopy (Withdrawn 2019)
WITHDRAWN RATIONALE
Formerly under the jurisdiction of Committee E04 on Metallography, this terminology was withdrawn in January 2019 in accordance with section 10.6.3 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
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Designation: E175 − 82 (Reapproved 2010)
Standard Terminology of
Microscopy
This standard is issued under the fixed designation E175; 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.
This standard has been approved for use by agencies of the Department of Defense.
Abbe condenser—see condenser, Abbe. aperture, angular—theanglebetweenthemostdivergentrays
that can pass through a lens to form the image of an object.
aberration—any error that results in image degradation. Such
errors may be chromatic, spherical, astigmatic, comatic,
aperture, effective—the diameter of the entrance pupil; it is
distortion,orcurvatureoffield;andcanresultfromdesignor
theapparentdiameterofthelimitingaperturemeasuredfrom
execution, or both.
the front.
achromatic—literally, color-free.Alens or prism is said to be
aplanatic—corrected for spherical aberration and coma.
achromatic when corrected for two colors. The remaining
apochromatic objective—a lens system whose secondary
color seen in an image formed by such a lens is said to be
chromatic aberrations have been substantially reduced. (See
secondary chromatic aberration.
achromatic).
achromatic objective—an objective that is corrected chro-
axis, optical—thelineformedbythecoincidingprincipalaxes
matically for two colors, and spherically for one, usually in
of a series of optical elements comprising an optical system.
the yellow-green part of the spectrum.
It is the line passing through the centers of curvature of the
Airy disk—the image of a bright point object, as focused by a
optical surfaces.
lens system. With monochromatic light, it consists of a
axis, optic—the direction, or directions in an anisotropic
central point of maximum intensity surrounded by alternate
crystal along which light is not doubly refracted.
circlesoflightanddarknesscausedbythereinforcementand
interference of diffracted rays. The light areas are called
balsam, Canada—aresinfromthebalsamfir Abies balsamea.
maxima and the dark areas minima.The distribution of light
Dissolved in xylene, toluene, or benzene it is used as a
from the center to the outer areas of the figure was
mountant for permanent microscopical preparations. Its
investigatedmathematicallybySirGeorgeAiry.Thediffrac-
refractive index may vary from 1.530 to 1.545 and its
tion disk forms a basis for determining the resolving power
softening point from room temperature to 100°C, these
of an ideal lens system. The diameter of the disk depends
properties varying with age and solvent content. If impure it
largely on the aperture of the lens. The diffraction of light
discolors with age.
causing theAiry disk is a factor limiting the resolution of a
Bertrand lens—see lens, Bertrand.
well corrected optical system.
bisectrix, acute—in biaxial crystals, that principal axis of the
analyzer—an optical device, capable of producing plane ellipsoid of indexes which bisects the smaller angle between
polarized light, used for detecting the state of polarization. the optic axes.
bisectrix, obtuse—inbiaxialcrystals,thatprincipalaxisofthe
a˚ngström unit—a unit of linear measure named after A. J.
−10
ellipsoid of indexes which bisects the larger angle between
Ångström. It is 1×10 metres; 1 µm=10,000 Å. It is
generally abbreviated asA. in the United States; elsewhere, the optic axes.
it is variously abbreviated Å , A., A.U., Å., or ÅU.
calcite—a doubly refracting mineral used in the manufacture
of polarizing prisms. It is uniaxial negative and in the
angular aperture—see aperture, angular.
trigonal diversion of the hexagonal system of crystals. Its
indexes are ϵ=1.486, ω =1.658; its hardness is 3 on the
Mohr scale and specific gravity 2.711.
This terminology is under the jurisdiction of ASTM Committee E04 on
Metallography and is the direct responsibility of Subcommittee E04.02 on Termi-
Canada balsam—see balsam, Canada.
nology
chromatic aberration—a defect in a lens or lens system as a
CurrenteditionapprovedJuly1,2010.PublishedJuly2010.Originallyapproved
result of which the lens possesses different focal lengths for
in 1961. Last previous edition approved in 2005 as E175–82(2005). DOI:
10.1520/E0175-82R10. radiation of different wavelengths.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E175 − 82 (2010)
collimation—the operation of controlling a beam of radiation darkfield condenser—see condenser, darkfield.
so that if the light source were a point, the light rays would
density. optical—logarithm to the vase 10 of the reciprocal of
become parallel. The total bundle of rays diverge as the
transmittance.
source size increases.
depth of field—the depth or thickness of the object space that
coma—a lens aberration occurring in that part of the image
is simultaneously in acceptable focus.
field that is some distance from the principal axis of the
system. It results from different magnification in the various
depth of focus—thedepthorthicknessoftheimagespacethat
lens zones. Extra-axial object points appear as short comet-
simultaneously in acceptable focus.
likeimageswiththebrightersmallheadtowardthecenterof
diaphragm—a fixed or adjustable aperture in an optical
the field (positive coma) or away from the center (negative
system. Diaphragms are used to intercept scattered light, to
coma).
limit field angles, or to limit image-forming bundles or rays.
compensating eyepieces—those designed for use with objec-
disk, Airy—see Airy disk.
tives such as apochromats in order to correct chromatic
aberration.
distance, interpupillary—see interpupillary distance.
condenser or condenser lens—a term applied to lenses or
dry objective—any microscope objective designed for use
mirrors designed to collect, control, and concentrate radia-
without immersion liquids.
tion in an illumination system.
electromagnetic lens—an electromagnet designed to produce
condenser, Abbe—originally a two-lens substage condenser
a suitably shaped magnetic field for the focusing and
combination designed by Ernst Abbe. It lacks chromatic
deflection of electrons or other charged particles in electron-
correction though designed for a minimum of spherical
optical instrumentation.
aberration and has only a very low-angle aplanatic cone. It
may be rated with a numerical aperture as high as 1.3. electron microscope—see microscope, electron.
condenser, darkfield—a condenser forming a hollow cone of electron optics—the science that deals with propagation of
light with its apex (or focal point) in the plane of the
electrons, as light optics deals with that of light and its
specimen. When used with an objective having a numerical phenomena.
aperture lower than the minimum numerical aperture of the
eye lens—see lens, eye.
hollow cone, only light deviated by the specimen enters the
objective. Objects are seen as bright images against a dark
eyepiece—the lens system used in an optical for magnification
background.
of the image formed by the objective.
condenser, darkfield, bispheric—a darkfield condenser con-
eyepiece, parfocal—eyepieces with common focal planes so
sisting of a convex spherical reflector mounted concentric
that they are interchangeable without refocusing.
with a larger concave reflector. The rays are formed into a
eyepiece, positive—aneyepieceinwhichtherealimageofthe
diverging cone by the convex reflector.The annular concave
object is formed below the lower lens elements of the
reflector then forms a hollow converging cone which is
eyepiece.
focused on the subject. See condenser, darkfield.
filar micrometer or filar eyepiece—an eyepiece equipped
condenser, darkfield, paraboloid—a darkfield condenser
with a fiducial line in its focal plane, that is movable by
consisting of a reflecting surface in the form of a segment of
means of a calibrated micrometer screw, in order to make
a paraboloid of revolution. Parallel rays entering the con-
accurate measurements of length.
denser around the periphery of the central stop are reflected
from the curved surfaces and converge at the focus of the
focus, principal—the point at which a lens focuses an axial
paraboloid. See condenser, darkfield.
object pint. Synonymous with focal point.
condenser, variable-focus—essentially anAbbe condenser in
illumination, critical—the formation of an image of the light
whichtheupperlenselementisfixedandthelowermovable.
source in the object field. (Also known as Nelson illumina-
The lower lens may be used to focus the illumination
tion)
between the elements so that it emerges from the stationary
lens as a large diameter parallel bundle. The field of illumination, Köhler—a method of microscopical illumina-
low-power objectives may thus be filled without removing tion, first described by A. Köhler, in which an image of the
thetopelement.Attheoppositeextremeitcanbeadjustedto source is focused in the lower focal plane of the condenser,
have a numerical aperture as high as 1.3. and the field diaphragm is focused in the specimen plane.
critical illumination—see illumination, critical.
illumination, oblique—illumination from light inclined at an
crystal, birefringent—apertainingtotheuseofamicroscope. oblique angle to the optical axis.
curvature of field—apropertyoflensthatcausestheimageof image—a representation of an object produced by means of
aplanetobefocusedintoacurvedsurfaceinsteadofaplane. radiation
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