1、Designation: F1863 10Standard Test Method forMeasuring the Night Vision Goggle-Weighted Transmissivityof Transparent Parts1This standard is issued under the fixed designation F1863; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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.INTRODUCTIONTest Methods D1003 and F1316 apply to the transmissivity measurement of transparent materials,the former be
3、ing for small flat samples, and the latter for any materials including larger, curved piecessuch as aircraft transparencies. Additionally, in Test Method D1003, the transmissivity is measuredperpendicular to the surface of test sample and both test methods measure only in the visible lightspectral r
4、egion. Night vision goggles (NVGs) are being used in aircraft and other applications (forexample, marine navigation, driving) with increasing frequency. These devices amplify both visibleand near-infrared (NIR) spectral energy. Overall visual performance can be degraded if the observeruses the NVGs
5、while looking through a transparency that has poor transmissivity in the visible andNIR spectral regions. This test method describes both direct and analytical measurement techniquesthat determine the NVG-weighted transmissivity of transparent pieces including ones that are large,curved, or held at
6、the installed position.1. Scope1.1 This test method covers apparatuses and procedures thatare suitable for measuring the NVG-weighted transmissivity oftransparent parts including those that are large, thick, curved,or already installed. This test method is sensitive to transpar-encies that vary in t
7、ransmissivity as a function of wavelength.1.2 Since the transmissivity (or transmission coefficient) is aratio of two radiance values, it has no units. The units ofradiance recorded in the intermediate steps of this test methodare not critical; any recognized units of radiance (for example,watts/m2-
8、str) may be used, as long as it is consistent.21.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regu
9、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D1003 Test Method for Haze and Luminous Transmittanceof Transparent PlasticsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precis
10、ion of a Test MethodF1316 Test Method for Measuring the Transmissivity ofTransparent Parts3. Terminology3.1 Definitions:3.1.1 analytical test method, nthe test method that usesspectral transmissivity data of a transparent part collected bythe use of either spectrophotometric or spectroradiometricins
11、trumentation. The data are then examined using analyticmethods to determine the NVG-weighted transmissivity of thepart.3.1.2 direct test method, nthe test method that uses theactual luminous output, as measured by a photometer, properlycoupled to the eyepiece of the test NVG. The NVG-weightedtransmi
12、ssivity of the part is then determined by forming the1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and Materials.Current edition approved May 1, 2010. Published June 2010. Or
13、iginallyapproved in 1998. Last previous edition approved in 2004 as F1863 98 (2004).DOI: 10.1520/F1863-10.2RCA Electro-Optics Handbook, RCA/Solid State Division/Electro Optics andDevices. Technical Series EOH-11. Lancaster, PA; 1974.3For referenced ASTM standards, visit the ASTM website, www.astm.or
14、g, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ratio of the
15、NVG output luminance with the transparent part inplace to the luminance output without the part.3.1.3 NVG-weighted spectral transmissivity, nthe spectraltransmissivity of a transparent part multiplied by the spectralsensitivity of a given NVG (see Fig. 1).3.1.4 NVG-weighted transmissivity (TNVG), nt
16、he spectraltransmissivity of a transparent part multiplied by the spectralsensitivity of a given NVG integrated with respect to wave-length (see Fig. 1, Eq 1 and Eq 2).3.1.5 NVG spectral sensitivity, nthe sensitivity of anNVG as a function of input wavelength.3.1.6 photometer, na device that measure
17、s luminous in-tensity or brightness by converting (weighting) the radiantintensity of an object using the relative sensitivity of the humanvisual system as defined by the photopic curve.2,43.1.7 photopic curve, nthe photopic curve is the spectralsensitivity of the human eye for daytime conditions as
18、 definedby the Commission Internationale dEclairage (CIE) 1931standard observer.2,43.1.8 transmission coeffcient, nsee transmissivity.3.1.9 transmissivity, nthe transmissivity of a transparentmedium is the ratio of the luminance of an object measuredthrough the medium to the luminance of the same ob
19、jectmeasured directly.4. Summary of Test Method4.1 General Test ConditionsThe test method can beperformed in any light-controlled area (for example, light-tightroom, darkened hangar, or outside at night away from stronglight sources). The ambient illumination must be very lowbecause of the extreme s
20、ensitivity of the NVGs.Afixture holdsthe NVG and its objective lens is aimed at and focused on atarget. The target can be either an evenly illuminated white,diffusely reflecting surface or a transilluminated screen (light-box). The illumination is provided by a white, incandescentlight source. Handl
21、e the samples carefully so as not to causeany damage. Do not clean them with any solvents. Usepart-specific, prescribed cleaning materials and methods.4.1.1 Direct Test MethodAttached directly to the eyepieceof the NVG is a photodetector. It has been found that themeasured field of view (FOV) should
22、 be smaller than theuniformly illuminated portion of the target. The target illumi-nation is adjusted so that the output of the NVGs is about 1.7cd/m2(0.5 fL). This ensures that the NVG input level issufficiently low that it does not activate the NVG automaticgain control (AGC) circuitry. The lumina
23、nce output of theNVG is measured with no transparency in place and thenrepeated with the transparent material in place between thelight source and the NVG. The transmissivity is equal to theNVG output luminance with the transparent material in placedivided by the NVG output luminance without the mat
24、erial(see Eq 1). The result is the NVG-weighted transmissivity(TNVG) of the transparent material.4.1.2 Analytical Test MethodWithout the sample in place,measure the light sources spectral energy distribution from450 through 950 nm in 5-nm incremental steps. Place thesample into the spectrophotometer
25、 or spectroradiometer fix-ture. Perform spectral measurements, also from 450 through950 nm in 5-nm incremental steps. Obtain from the NVGmanufacturer the spectral sensitivity of the goggle that will beused in conjunction with the part. Perform the analytic methodas defined in Eq 2 to derive the TNVG
26、.5. Significance and Use5.1 SignificanceThis test method provides a means tomeasure the compatibility of a given transparency throughwhich NVGs are used at night to view outside, nighttimeambient illuminated natural scenes.4Wyszecki, Gunter, and Stiles, WS, Color Science: Concepts and Methods,Quanti
27、tative Data and Formulae, 2nd ed., New York, John Wiley and Sons, 1982.FIG. 1 An Example of How the Spectral Sensitivity of a Generation 3 NVG Multiplied by the Spectral Transmissivity of a TransparentPart Equals the NVG-Weighted Spectral Transmissivity of that Part. Integrating the Curve with Respe
28、ct to Wavelength Yields the PartsNVG-Weighted Transmissivity (TNVG) ValueF1863 1025.2 UseThis test method may be used on any transparentpart, including sample coupons. It is primarily intended for useon large, curved, or thick parts that may already be installed(for example, windscreens on aircraft)
29、.6. Apparatus6.1 Test EnvironmentThis test method can be performedin any light-controlled area (for example, light-tight room,darkened hangar, or outside at night away from strong lightsources) since the NVGs are extremely sensitive to both visibleand near infrared light. Extraneous light sources (f
30、or example,exit signs, telephone pole lights, status indicator lights onequipment, and so forth) can also interfere with the measure-ment.6.2 White Diffuse TargetThe white target can be anyuniformly diffusely reflecting or translucent material (forexample, cloth, flat white painted surface, plastic)
31、. The targetarea should be either smaller (see Fig. 2) or larger (see Fig. 3)than the NVG FOV (35 to 60 typical) to minimize potentialalignment errors.6.3 Light SourceThe light source should be regulated toensure that it does not change luminance during the readingperiod. It should be a low output,
32、2856K incandescent lightsince this type emits sufficient energy in both visible andinfrared without any sharp emission peaks or voids.2Its outputmust be uniformly distributed over the measurement area of thewhite diffuse target. Use of neutral density filters or varying thelamp distance may be neede
33、d to achieve sufficiently lowluminance levels to be obtained for test, since varying theradiators output would shift its color temperature.6.4 Night Vision GogglesA family of passive imageintensifying devices that use visible and near-infrared light andenable the user to see objects that are illumin
34、ated by fullmoonlight through starlight-only conditions. The goggle that isused for test should be the same as that intended to be usedwith the given transparent material.6.5 PhotometerAny calibrated photometer may be usedfor this measurement. However, the detector must be properlycoupled to the NVG
35、 eyepiece, and the FOV over which thelight is integrated must be known.7. Test Specimen7.1 If necessary, clean the part to be measured using theprocedure prescribed for the specific material. Use of non-standard cleaning methods can irrevocably damage the part.No special conditions other than cleani
36、ng are required.8. Calibration and Standardization8.1 It is not necessary that the photometer be calibrated inabsolute luminance units since the measurement involves thedivision of two measured quantities yielding a dimensionlessvalue. A generic photodetector can be substituted for thephotometer if
37、its FOV is known.9. Procedure9.1 General ProceduresPerform all measurements in adarkened, light-controlled area. To control the effects ofreflection, verify that there are no extraneous light sources thatcan produce reflections within the measurement area of thetransparent material. To control the e
38、ffects of haze, verify thatno light other than the measurement light falls on the areabeing tested.9.2 Direct Test MethodThis test method allows analysisof large or small transparent parts placed at either normal(perpendicular to the optical axis) or installed orientations,such as an aircraft windsc
39、reen. Fig. 2 illustrates the use of asmall, transilluminated lightbox. Fig. 3 depicts the use of alarge, front-illuminated, white, diffusely reflective target, illu-minated as uniformly as possible using a regulated whiteincandescent light source. The size of the target is dependentupon the test loc
40、ation, the obtainable luminance uniformity,and the FOV of the photodetector assembly. In the field, atransilluminated lightbox is probably the easiest to set up anduse, as it offers the advantage of compact, self-containedportability. Maintain the same target-to-NVG distance duringthe measurements.
41、In a light-tight room, a white, diffuselyFIG. 2 Direct Test Method Equipment Set Up to Measure the Night Vision Goggle-Weighted Transmissivity of a Transparent Part Usinga Transilluminated Lightbox that Underfills the NVG FOVF1863 103reflecting, front-illuminated surface may be used. In the field,th
42、e NVG can be held by hand and under laboratory conditions,can be mounted in a sturdy fixture.Aim and focus the NVG onthe white target.Attach the photodetector to the NVG eyepiece.With the transparent material removed from the measurementpath, adjust the variable white light to produce an NVG outputl
43、uminance of about 1.7 cd/m2(0.5 fL). This ensures that theNVGs input is not saturated; the AGC is not activated. As aresult of the extreme sensitivity of NVGs, neutral density filtersmay need to be placed in front of the light source or the NVGsto obtain low enough apparent target luminance. After r
44、ecord-ing the NVGs output luminance, place the transparent materialin the measurement path. If the material is a sample, itsorientation relative to the measurement path can be simplyperpendicular or at the installed angle. If an aircraft transpar-ency is being tested, the NVG should be located at th
45、e designeye position relative to the transparency, which is mounted inits installed position. Measuring at the installed angle is criticalsince many materials exhibit variations in transmissivity as afunction of angle. Record the NVGs output with the test piecein place. To prevent damage to the NVGs
46、, verify that they areturned off before the test area lights are turned on.9.2.1 There are numerous classes of NVGs (Generations 2,3; Types A, B, C) that vary in their spectral sensitivity,intensified FOV, resolution, and so forth. It is important toselect the proper NVG type that will be used in a
47、givenapplication. The NVG must also be in good working conditionand meet minimum user performance specifications.9.2.2 The target illumination source can be an incandescentlight operating at 2856K, which is the standard color tempera-ture that is used for many NVG test procedures. The illumina-tion
48、from this source can be varied using neutral density filters,since varying the lights voltage would cause a correspondingcolor temperature shift. If the NVG is to be used to view anarea through a specific transparent material that is illuminatedby a different kind of light source (for example, mercu
49、ry vapor,sodium), then that source must be properly noted in the testreport.9.2.3 The luminance output of the NVG is measured andthen repeated with the transparent material in place. Thetransmissivity is equal to the NVG output luminance with thetransparent material in place divided by the NVG outputluminance without the material (see Eq 1). The result is theNVG-weighted transmissivity (TNVG) of the transparent mate-rial.9.3 Analytical Test MethodWhen using a spectrophotom-eter, the sample is usually limited to about 2- by 2-in. samplecoupons held i
