1、Designation:E154314Standard Practice forNoise Equivalent Temperature Difference of ThermalImaging Systems1This standard is issued under the fixed designation E1543;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revi
2、sion.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This practice covers the determination of the noiseequivalent temperature difference(NETD;NET)of thermalimaging systems of the conv
3、entional forward-looking infrared(FLIR)or other types that utilize an optical-mechanical scan-ner;it does not include charge-coupled devices or pyroelectricvidicons.1.2 Parts of this practice have been formulated under theassumption of a photonic detector(s)at a standard backgroundtemperature of 295
4、K(22C).Besides nonuniformity,exami-nations made at other background temperatures may result inimpairment of precision and bias.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all
5、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 regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E1213 Practice for Minimum
6、 Resolvable Temperature Dif-ference for Thermal Imaging SystemsE1316 Terminology for Nondestructive Examinations3.Terminology3.1 Definitions:3.1.1 blackbody simulatora device that produces an emis-sion spectrum closely approximating that emitted by a black-body(surface with emissivity of 1.0),usuall
7、y a cavity or a flatplate with a structured or coated surface having a stable anduniform temperature.3.1.2 dwell timethe time spent,during one frame,inscanning one angular dimension of a single pixel(pictureelement)of the image within the instantaneous field of view(IFOV)of a detector.Thus,for examp
8、le,if a single pixel isscanned n times during one frame,the dwell time is given byn times the duration of a single scan of the pixel.3.1.3 FLIRan acronym for forward-looking infrared,originally implying airborne,now denoting any fast-framethermal imaging system comparable to that of television andyi
9、elding real-time displays.Generally,these systems employoptical-mechanical scanning mechanisms.3.1.4 See also Section J:Infrared Examination,of Termi-nology E1316.4.Summary of Practice4.1 The target is a blackbody source of uniform temperaturethat is viewed by the infrared thermal imaging system thr
10、oughan aperture of prescribed size.A specified temperature differ-ence is established between the target and its background.Measurements are made of the peak-to-peak signal voltagefrom the target and the RMS noise voltage from thebackground,both across a standard reference filter,and of thetarget an
11、d background temperatures.From these measuredvalues,the NETD is calculated.5.Significance and Use5.1 This practice gives an objective measure of the tempera-ture sensitivity of a thermal imaging system(relative to astandard reference filter)exclusive of a monitor,with emphasison the detector(s)and p
12、reamplifier.NOTE1Test values obtained under idealized laboratory conditionsmay or may not correlate directly with service performance.5.2 This practice affords a convenient means for periodi-cally monitoring the performance of a given thermal imagingsystem.5.3 NETD relates to minimum resolvable temp
13、erature dif-ference as described in Practice E1213.Thus,an increase inNETD may be manifest as a loss of detail in imagery.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.10 onSpecialized NDT Methods.Curren
14、t edition approved Oct.1,2014.Published October 2014.Originallyapproved in 1993.Last previous edition approved in 2011 as E1543-00(2011).DOI:10.1520/E154314.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMSt
15、andards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.4 Intercomparisons based solely
16、on NETD figures may bemisleading.NOTE2NETD depends on various factors such as spectral bandwidthand background temperature.6.Apparatus6.1 The apparatus,as shown in Fig.1,consists of thefollowing:6.1.1 Blackbody Simulator,temporally stable and control-lable to within 0.1C.6.1.2 Target Plate,containing an aperture several timeslarger dimensionally than the IFOV.The target plate should beat least ten times the dimension of the aperture in both theheight and width.(The plate forms the target backgro