1、Designation: E 349 06Standard Terminology Relating toSpace Simulation1This standard is issued under the fixed designation E 349; 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 ind
2、icates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThese definitions pertain to technologies related to space environment simulation. Where possible,existing international and national standard definitions have
3、 been used.ELECTROMAGNETIC RADIATION TERMSFUNDAMENTAL CONCEPTSabsorption, ntransformation of radiant energy to a differentform of energy by interaction with plex radiation, nradiation composed of a number ofmonochromatic radiations.diffusion, nchange of the spatial distribution of a beam ofradiation
4、 when it is deviated in many directions by a surfaceor a medium.emission, n release of radiant energy.infrared radiation, nradiation for which the wavelengths ofthe monochromatic components are greater than those forvissible radiation, and less than about 1 mm.NOTE 1The limits of the spectral range
5、of infrared radiation are notwell defined and may vary according to the user. Committee E-2.1.2 of theCIE distinguishes in the spectral range between 780 nm and 1 mm:IR-A 780 to 1400 nmIR-B 1.4to3mIR-C 3mto1mmirradiation, napplication of radiation to an object.monochromatic radiation, nradiation cha
6、racterized by asingle frequency. By extension, radiation of a very smallrange of frequency or wavelength that can be described bystating a single frequency or wavelength.radiation, n(1) emission or transfer of energy in the form ofelectromagnetic waves or particles.(2) the electromagnetic waves or p
7、articles.NOTE 2In general, nuclear radiations and radio waves are notconsidered in this vocabulary, only optical radiations, that is, electromag-netic radiations (photons) of wavelengths lying between the region oftransition to X-rays (1 nm) and the region of transition to radio waves (1mm).reflecti
8、on, nreturn of radiation by a surface without changeof frequency of the monochromatic components of which theradiation is composed.refraction, nchange in the direction of propagation ofradiation determined by change in the velocity of propaga-tion in passing from one medium to another.spectrum of ra
9、diation, n(1) spatial display of a complexradiation produced by separation of its monochromaticcomponents.(2) composition of a complex radiation.transmission, npassage of radiation through a mediumwithout change of frequency of the monochromatic compo-nents of which the radiation is composed.ultravi
10、olet radiation, nradiation for which the wavelengthsof the monochromatic components are smaller than those forvisible radiation and more than about 1 nm.NOTE 3The limits of the spectral range of ultraviolet radiation are notwell defined and may vary according to the user. Committee E-2.1.2 of theCIE
11、 distinguishes in the spectral range between 100 and 400 nm:UV-A 315 to 400 nmUV-B 280 to 315 nmUV-C 100 to 280 nmvisible radiation, nany radiation capable of causing a visualsensation.NOTE 4The limits of the spectral range of visible radiation are notwell defined and may vary according to the user.
12、 The lower limit isgenerally taken between 380 and 400 nm and the upper limit between 760and 790 nm (1 nanometer, nm = 109m).QUANTITIESabsorptance, nratio of the absorbed radiant or luminous fluxto the incident flux. Symbol: ae, av, a.1These definitions are under the jurisdiction ofASTM Committee E2
13、1 on SpaceSimulation and Applications of Space Technology and are the direct responsibilityof Subcommittee E21.02 on Terminology, Units, and Editorial.Current edition approved April 1, 2006. Published April 2006. Originallyapproved in 1968. Last previous edition approved in 2000 as E 349 00.1Copyrig
14、ht ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 5In general, the value of the absorptance depends upon themode of irradiation, the spectral composition, and the state of polarizationof the incident radiation.absorptivity of an absorbing
15、 material, ninternal absorp-tance of a layer of the material such that the path of theradiation is of unit length.diffuse reflection, ndiffusion by reflection in which, on themacroscopic scale, there is no regular reflection.diffuse transmission, ntransmission in which diffusion oc-curs independentl
16、y, on the macroscopic scale, of the laws ofrefraction.directional emissivity of a thermal radiator, nratio of thethermal radiance of the radiator in a given direction to that ofa full radiator at the same temperature. Symbol: e(u, f); e(u,f)=Le,th(u,f)/Le(e =1).emissivity of a thermal radiator, nrat
17、io of the thermalradiant exitance of the radiator to that of a full radiator at thesame temperature. Symbol: e, e = Me,th/Me(e = 1).NOTE 6Formerly “pouvoir missif” (fr.).frequency, nreciprocal of the period. Symbol; f, n.NOTE 7When the independent variable is time, the unit of frequencyis the hertz.
18、 Symbol: Hz (1 Hz = 1 s1). (This unit is also called “cycle persecond,” c/s.)full radiator: blackbody (USA), Planckian radiator,nthermal radiator that absorbs completely all incidentradiation, whatever the wavelength, the direction of inci-dence, or the polarization. This radiator has, for any wave-
19、length, the maximum spectral concentration of radiant exi-tance at a given temperature.goniophotometer, nphotometer for measuring the direc-tional light distribution characteristics of sources, lightingfittings, media, and surfaces.NOTE 8A goniophotometer for measuring the spatial distribution oflum
20、inous intensity is also called a distribution photometer.gray body, nnonselective radiator whose spectral emissivityis less than one.integrating (Ulbrecht) sphere, npart of an integratingphotometer. A sphere that is coated internally with a whitediffusing paint as nonselective as possible and is pro
21、videdwith an associated equipment for making a photometricmeasurement at a point of the inner surface of the sphere. Ascreen placed inside the sphere prevents the point underobservation from receiving any radiation directly from thesource.internal absorptance of a homogeneous nondiffusing plate,nrat
22、io of the radiant or luminous flux absorbed betweenthe entry and exit surfaces of the plate to the flux whichleaves the entry surface. Symbol: ai, ai+ ti=1.NOTE 9For a given plate, the internal absorptance is a function of thepath length of the radiation in the plate and thus of the angle of inciden
23、ce.The fundamental concept is spectral internal absorptance. ai(l).internal transmission density, nlogarithm to the base 10 ofthe reciprocal of the internal transmittance. Symbol: Di,Di= log10ti.NOTE 10See Note 12 of internal transmittance.NOTE 11In German, the symbol E is still in use and the natur
24、allogarithm is also used sometimes instead of the common logarithm; thecorresponding quantity is then called “natrliches Absorptionsmass.”(= In 1/ti).internal transmittance of a homogeneous nondiffusingplate, nratio of the radiant or luminous flux reaching theexit surface of the plate to the flux wh
25、ich leaves the entrysurface.NOTE 12For a given plate, the internal transmittance is a function ofthe path length of the radiation in the plate and thus of the angle ofincidence. The fundamental concept is “spectral internal transmittance”t(l).irradiance at a point on a surface, nquotient of the radi
26、antflux incident on an element of the surface containing thepoint by the area of that element. Symbol: Ee, E; Ee=dFe/dA; Unit: Watt per square metre, Wm2.NOTE 13In ultraviolet radiation therapy and photobiology, this quan-tity is called dose rate (International Photobiology Committee, 1954).linear a
27、bsorption coefficient of an absorbing medium,nquotient of the internal absorptance of a path elementtraversed by the radiation, by the length d of this element.Symbol: a;dF = aFdl; Unit: m1; al =ln10Di.NOTE 14The linear absorption coefficient is also the part of the linearattenuation coefficient tha
28、t is due to absorption.NOTE 15In German practice, a linear absorption coefficient is alsodefined for a homogeneous medium of finite thickness d, as the quotientof the “Absorptions-mass” (logarithm of the reciprocal of the internaltransmittance), by the thickness d of the layer. According to whether
29、thenatural logarithm or the logarithm to the base 10 is used, one maydistinguish the “natrliche Absorptionskoeffizient” (mn) quotient of the“natrliche Absorptionsmass” (see Note 2, internal transmission den-sity) by the thickness d of the layer traversed by the radiation, and the“dekadischeAbsorptio
30、nskoeffizient” (m) quotient of the internal transmis-sion density by the thickness d of the layer.NOTE 16a/r, where r is the density of the medium, is called “massabsorption coefficient.”linear attenuation (extinction) coefficient of an absorbingand diffusing medium, for a collimated beam of radiati
31、on,nquotient of the relative decrease in spectral concentrationof radiant or luminous flux of a collimated beam of radiationduring traversal with normal incidence of an infinitesimallayer of the medium by the thickness of that layer. Symbol:;dF =Fdl; Unit: m1.NOTE 17This concept only applies strictl
32、y to slightly diffusing media.NOTE 18/r, where r is the density of the medium, is called the“mass attenuation coefficient.”mixed reflection, npartly regular and partly diffuse reflec-tion.NOTE 19The irradiance or illuminance received from a point sourceafter regular (diffuse) reflection varies inver
33、sely as the square of thedistance to the source (diffuser).mixed transmission, npartly regular and partly diffusetransmission.NOTE 20The irradiance or illuminance received from a point source,after regular (diffuse) transmission, varies inversely as the square of thedistance to the source (diffuser)
34、.E349062nonselective radiator, nthermal radiator whose spectralemissivity is independent of wavelength over the rangeconsidered.opaque body, nbody that transmits practically no light.period, nsize of the minimum interval of the independentvariable after which the same characteristics of a periodicph
35、enomenon recur.NOTE 21In radiation, the independent variable is the time and thecorresponding quantity is the periodic time: Symbol: T; Unit: second (s).photometer, ninstrument used for measuring photometricquantities.photometry, nmeasurement of quantities referring to radia-tion, evaluated accordin
36、g to the visual effect which itproduces, as based on certain conventions.radiance (in a given direction, at a point on the surface of asource or receptor or at a point in the path of a beam), ,nquotient of the radiant flux leaving, arriving at, orpassing through an element of surface at this point a
37、ndpropagated in directions defined by an elementary conecontaining the given direction by the product of the solidangle of the cone and the area of the orthogonal projection ofthe element of surface on a plane perpendicular to the givendirection. Symbol: Le, L; Le=d2F (dv dA cos Q); Unit: Wattper st
38、eradian and per square metre, Wsr1m2.NOTE 22Three special cases may be noted:Case 1At a point on the surface of a source, in a given direction,radiance is also the quotient of the radiant intensity in the given directionof an element of the surface at this point, by the area of the orthogonalproject
39、ion of this element on a plane perpendicular to this direction(radiant intensity per unit projected area). Le=dIe/(dA cos Q).Case 2At a point on the surface of a receptor, in a given direction,radiance is also the quotient of the irradiance that is received at this pointon a surface perpendicular to
40、 the given direction by the solid angle of theelementary cone containing this direction and surrounding the beam whichproduces this irradiance (perpendicular irradiance per unit solid angle).Le=dEe/dv.Case 3On the path and in the direction of an element of a beam, ina nondiffusing, nonabsorbing medi
41、um, the radiance is also the quotient ofthe radiant flux dFewhich transports the beam, by the geometric extentdG of the beam. The geometric extent, which may be defined by twosections of the beam of areas dA and dA8 of separation l, and having anglesQ and Q8 between their normals and the direction o
42、f the beam is dG =dAcos Q dv where the numerical value in steradians of dv is dA8 cos Q8l2.L0=dF0/dG =d2Fe/(dv dA cos Q). In the absence of diffusion, it can bedemonstrated in geometrical optics that the optical extent, product of thegeometric extent of an element of a beam and the square of the ref
43、ractiveindex of the medium of propagation, is an invariant along the length of thebeam whatever the deviations that it undergoes by reflection or refraction(dGn2= constant). In consequence, the basic radiance, quotient of theradiance by the square of the refractive index, is invariant along the leng
44、thof an element of a beam if losses by absorption or by reflection are takenas zero (Len2= constant).radiance factor at a point on the surface of a nonself-radiatingbody, in a given direction under specified conditions ofirradiation, nratio of the radiance of the body to that of aperfect reflecting
45、or transmitting diffuser, identically irradi-ated. Symbol: b.radiant efficiency of a source of radiation, nratio of theradiant flux emitted to the power consumed. Symbol: he, h.NOTE 23The radiant efficiency of a source in a limited region of thespectrum may also be considered, that is, the ratio of
46、the radiant fluxemitted in this spectral region to the power consumed.radiant energy, nenergy emitted, transferred, or received asradiation. Symbol: Qe, Q; Unit: joule J (1 J = Ws).NOTE 24In ultraviolet radiation therapy and photobiology, this quan-tity is called “integral dose” (International Photo
47、biology Committee,1954).radiant exposure at a point on a surface, nsurface densityof the energy received. Symbol: He, H; He=dQe/dA = * Eedt; Unit: joule per square metre, Jm2.NOTE 25Formerly “irradiation.”NOTE 26Equivalent definition: Product of an irradiance and itsduration.NOTE 27In ultraviolet ra
48、diation therapy and photobiology, this quan-tity is called dose (International Photobiology Committee, 1954).radiant exitance at a point on a surface, nquotient of theradiant flux leaving an element of the surface containing thepoint, by the area of that element. Symbol: Me, M; Me=dFe/dA = *2Lecos u
49、dv. Unit: Watt per square metre, Wm2.NOTE 28The name radiant emittance previously given to this quantityis abandoned because it has given rise to confusion. Thus, the term“emittance” has been used to designate either the flux per unit area leavinga surface (whatever the origin of the flux), the flux per unit area emittedby a surface (flux originating in the surface), or, principally, in certaincircles in the United States of America, a quantity without dimensionssimilar to
