ASTM_E_175_-_82_2010.pdf

Designation:E17582(Reapproved 2010)Standard Terminology ofMicroscopy1This standard is issued under the fixed designation E175;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript 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 condensersee condenser,Abbe.aberrationany error that results in image degradation.Sucherrors may be chromatic,spherical,astigmatic,comatic,distortion,or curvature of field;and can result from design orexecution,or both.achromaticliterally,color-free.A lens or prism is said to beachromatic when corrected for two colors.The remainingcolor seen in an image formed by such a lens is said to besecondary chromatic aberration.achromatic objectivean objective that is corrected chro-matically for two colors,and spherically for one,usually inthe yellow-green part of the spectrum.Airy diskthe image of a bright point object,as focused by alens system.With monochromatic light,it consists of acentral point of maximum intensity surrounded by alternatecircles of light and darkness caused by the reinforcement andinterference of diffracted rays.The light areas are calledmaxima and the dark areas minima.The distribution of lightfrom the center to the outer areas of the figure wasinvestigated mathematically by Sir GeorgeAiry.The diffrac-tion disk forms a basis for determining the resolving powerof an ideal lens system.The diameter of the disk dependslargely on the aperture of the lens.The diffraction of lightcausing the Airy disk is a factor limiting the resolution of awell corrected optical system.analyzeran optical device,capable of producing planepolarized light,used for detecting the state of polarization.a ngstrm unita unit of linear measure named after A.J.ngstrm.It is 1 1010metres;1 m=10,000.It isgenerally abbreviated as A.in the United States;elsewhere,it is variously abbreviated ,A.,A.U.,.,or U.angular aperturesee aperture,angular.aperture,angularthe angle between the most divergent raysthat can pass through a lens to form the image of an object.aperture,effectivethe diameter of the entrance pupil;it isthe apparent diameter of the limiting aperture measured fromthe front.aplanaticcorrected for spherical aberration and coma.apochromatic objectivea lens system whose secondarychromatic aberrations have been substantially reduced.(Seeachromatic).axis,opticalthe line formed by the coinciding principal axesof a series of optical elements comprising an optical system.It is the line passing through the centers of curvature of theoptical surfaces.axis,opticthe direction,or directions in an anisotropiccrystal along which light is not doubly refracted.balsam,Canadaa resin from the balsam fir Abies balsamea.Dissolved in xylene,toluene,or benzene it is used as amountant for permanent microscopical preparations.Itsrefractive index may vary from 1.530 to 1.545 and itssoftening point from room temperature to 100C,theseproperties varying with age and solvent content.If impure itdiscolors with age.Bertrand lenssee lens,Bertrand.bisectrix,acutein biaxial crystals,that principal axis of theellipsoid of indexes which bisects the smaller angle betweenthe optic axes.bisectrix,obtusein biaxial crystals,that principal axis of theellipsoid of indexes which bisects the larger angle betweenthe optic axes.calcitea doubly refracting mineral used in the manufactureof polarizing prisms.It is uniaxial negative and in thetrigonal diversion of the hexagonal system of crystals.Itsindexes are =1.486,v=1.658;its hardness is 3 on theMohr scale and specific gravity 2.711.Canada balsamsee balsam,Canada.chromatic aberrationa defect in a lens or lens system as aresult of which the lens possesses different focal lengths forradiation of different wavelengths.1This terminology is under the jurisdiction of ASTM Committee E04 onMetallography and is the direct responsibility of Subcommittee E04.02 on Termi-nologyCurrent edition approved July 1,2010.Published July 2010.Originally approvedin 1961.Last previous edition approved in 2005 as E175 82(2005).DOI:10.1520/E0175-82R10.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 collimationthe operation of controlling a beam of radiationso that if the light source were a point,the light rays wouldbecome parallel.The total bundle of rays diverge as thesource size aa lens aberration occurring in that part of the imagefield that is some distance from the principal axis of thesystem.It results from different magnification in the variouslens zones.Extra-axial object points appear as short comet-like images with the brighter small head toward the center ofthe field(positive coma)or away from the center(negativecoma).compensating eyepiecesthose designed for use with objec-tive