BS ISO 18251-1-2017 Non-destructive testing Infrared thermography Characteristics of system and equipment《无损试验 红外热成像法 系统和设备特性》.pdf

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1、BS ISO 18251-1:2017Non-destructive testing Infrared thermographyPart 1: Characteristics of system andequipmentBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 18251-1:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 18

2、251-1:2017. The UK participation in its preparation was entrusted to TechnicalCommittee WEE/46, Non-destructive testing.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a con

3、tract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 82616 0 ICS 19.100 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the aut

4、hority of the Standards Policy and Strategy Committee on 31 January 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 18251-1:2017 ISO 2017Non-destructive testing Infrared thermography Part 1: Characteristics of system and equipmentEssais non destructifs Thermogra

5、phie infrarouge Partie 1: Caractristiques du systme et des quipementsINTERNATIONAL STANDARDISO18251-1First edition2017-02Reference numberISO 18251-1:2017(E)BS ISO 18251-1:2017ISO 18251-1:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights r

6、eserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either

7、 ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 18251-1:2017ISO 18251-1:2017(E)Foreword vIntroduction vi1 Scope .

8、 12 Normative references 13 Terms and definitions . 14 IR system setup 15 Objective lens . 25.1 General . 25.2 Spectral response 25.3 Focal length (mm) 25.4 Aperture f-number 25.5 Interchangeable object lenses . 36 Detector . 36.1 General . 36.2 Detector types 36.3 Detector arrays . 36.4 Scanning sy

9、stems 36.5 Working wavelength range . 36.6 Number of pixels . 46.7 Bad/dead pixel 46.8 Detector operability 46.9 Thermal time constant . 46.10 Integration time . 46.11 Temperature range 47 Image processor 47.1 General . 47.2 Image acquisition 47.2.1 Timing acquisition 47.2.2 Trigger acquisition . 57

10、.2.3 Image freeze . 57.3 Image display . 57.4 Image analysis . 57.5 Image processing 57.5.1 General 57.5.2 Bad/dead pixel replacement . 57.5.3 Non-uniformity correction 57.5.4 Image enhancement 57.5.5 Filtering . 67.5.6 Time correlated processing method . 67.5.7 Visible-infrared image fusion 67.6 Im

11、age recording . 68 Thermal stimulation source . 68.1 General . 68.2 Optical radiation devices 68.3 Convective excitation devices . 68.4 Electromagnetic induction devices . 78.5 Mechanical excitation devices . 78.6 Advantages and drawbacks of thermal stimulation sources . 79 Integrated characteristic

12、s and functions of infrared systems and equipment 79.1 Integrated performance parameters 79.1.1 Noise equivalent temperature difference (NETD) 7 ISO 2017 All rights reserved iiiContents PageBS ISO 18251-1:2017ISO 18251-1:2017(E)9.1.2 Minimum resolvable temperature difference (MRTD) . 89.1.3 Minimum

13、detectable temperature difference (MDTD) . 89.1.4 Field of view (FOV) 89.1.5 Instantaneous field of view (IFOV) 89.1.6 Minimum working distance . 89.1.7 Maximum temperature measurement range 89.1.8 Temperature measurement uniformity . 89.1.9 Operating temperature range . 99.2 Integrated functions .

14、99.2.1 Digital input/output interface 99.2.2 Data transfer interface 99.2.3 Video output interface 910 Accessories . 910.1 Infrared mirror . 910.2 Attenuation filter . 910.3 Spectral filters 910.4 Tripod . 910.5 Reference blocks 9Bibliography .10iv ISO 2017 All rights reservedBS ISO 18251-1:2017ISO

15、18251-1:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject

16、 for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC)

17、on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be note

18、d. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifyin

19、g any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents).Any trade name used in this document is information given for the convenienc

20、e of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the fo

21、llowing URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee SC 8, Thermographic testing.A list of all parts in the ISO 18251 series can be found on the ISO website. ISO 2017 All rights reserved vBS ISO 18251-1:20

22、17ISO 18251-1:2017(E)IntroductionThe industrial applications of infrared thermographic testing in non-destructive testing (NDT) are growing, along with a remarkable improvement in thermographic technologies. The effectiveness of any application of infrared thermographic testing depends upon proper a

23、nd correct usage of the system and equipment. The purpose of this document is to provide the characterization description of system and equipment for infrared thermography in the field of industrial NDT. The development of this document resolves the lack of International Standards on infrared equipm

24、ent and systems. The main interested parties who will benefit from this document are manufacturers and users of such equipment and systems.vi ISO 2017 All rights reservedBS ISO 18251-1:2017Non-destructive testing Infrared thermography Part 1: Characteristics of system and equipment1 ScopeThis docume

25、nt describes the main components, and their characteristics, constituting an infrared (IR) imaging system and related equipment used in non-destructive testing (NDT). It also aims to assist the user in the selection of an appropriate system for a particular measurement task.The following items are s

26、pecified: objective lens; detector; image processor; display; thermal stimulation source; accessories.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the ed

27、ition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 10878, Non-destructive testing Infrared thermography Vocabulary3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 10878 appl

28、y.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp4 IR system setupFigure 1 represents an imaging arrangement

29、 including the IR system. The lens focuses an image of the object on the detector. The array of pixels in the detector produces electrical signals dependent on infrared radiation intensity. The electrical signals are processed to produce an image that is shown on a display and available for storage

30、or further processing.INTERNATIONAL STANDARD ISO 18251-1:2017(E) ISO 2017 All rights reserved 1BS ISO 18251-1:2017ISO 18251-1:2017(E)Figure 1 IR system setup5 Objective lens5.1 GeneralThe objective lens of an optical system is the element, or combination of elements, that focuses radiant energy from

31、 the object and forms the primary image.Interchangeable lenses are used to reach a desired spatial resolution of the investigated object, or object detail.5.2 Spectral responseIR-cameras are adapted to the transmission properties of the atmosphere for infrared radiation (atmospheric windows): Short

32、Wave, SW: wavelength between approx. 0,8 m and 2 m; Mid Wave, MW: wavelength between approx. 3 m and 5 m; Long Wave, LW: wavelength between approx. 8 m and 14 m.The spectral response of the IR-camera depends on the used detector. The transmission of the objective lens system should be adapted to the

33、 spectral response of the detector. The detector is selected according to the test problem.5.3 Focal length (mm)The focal length is the distance between optical centre of the lens and the focal plane point of the detector. The image of an observed object differs according to the focal length of the

34、lens. A long focal length results in a smaller field of view and a larger image on the focal plane; this can be useful for increasing the working distance or visualizing fine details of an object.5.4 Aperture f-numberThe aperture defines the opening through which the rays come to a focus on the foca

35、l plane array. The effective size of the lens aperture affects the amount of radiant energy that passes through a lens. It is usually specified as an f-number, the ratio of the focal length to the effective aperture diameter. It strongly influences the sensitivity of the infrared detector. A larger

36、aperture, a lower f-number, allows more radiant energy to reach the detector, increasing sensitivity of the system. These are “fast” apertures like f/1.1 or f/2. A smaller aperture, a higher f-number, allows less light that gets in. These are “slow” apertures like f/3 or f/4.5.2 ISO 2017 All rights

37、reservedBS ISO 18251-1:2017ISO 18251-1:2017(E)The lens aperture diameter needs to be greater than the detector diagonal to ensure that most of the radiant energy hitting the detector comes through the lens rather than from the internal parts of the system enclosure.Detector aperture and lens apertur

38、e have to be carefully matched. It is beneficial to keep the lens system slightly faster than the detector in order to improve the ratio of rays accumulated by the lens system to the rays incoming from lens housing and other internal components.5.5 Interchangeable object lensesInterchangeable object

39、 lenses are used to adapt the camera system to special geometric requirements of measurement tasks (image section, required minimal resolution). There are typically standard object lenses, e.g. wide angle and telephoto lenses as well as accessory lenses for the measurement of large or small objects.

40、 For improved accuracy, each object lens shall be calibrated together with the camera.6 Detector6.1 GeneralThe detector represents the core of the infrared camera since it senses infrared radiation and converts it to a usable electrical signal. Several characteristics affect the performance of the d

41、etector system. The type, number and arrangement of detector elements affect the sensitivity, thermal resolution, response time and spectral response of the imaging system.6.2 Detector typesThere are many different kinds of detectors available in infrared equipment, such as microbolometer, photoelec

42、tric, pyroelectric or quantum sensor, etc. These detectors are classified as two types: thermal detectors and quantum detectors. Thermal detectors, e.g. microbolometers or pyroelectric detectors, work at room temperature. Quantum detectors, e.g. photoelectric detectors or QWIP detectors, have to be

43、cooled down to very low temperatures to reduce thermal noise. Quantum detectors have a higher sensitivity and they are easily compatible with higher frame modes of image acquisition.6.3 Detector arraysInfrared detectors can be single, linear arrays or two-dimensional arrays. Single element detectors

44、 require a scanning system to direct radiation from successive parts of the image at the detector in an organized two-dimensional scan that can be decoded into an image. Linear arrays can be used for producing images of moving objects, such as production lines. Two-dimensional detector arrays focal

45、plane array (FPA) are capable of recording images without scanning.6.4 Scanning systemsMechanical scanning is achieved by moving mirrors, prisms, or polygons. Scanning cameras inherently provide homogeneous images without electronic correction mechanisms. However, the frame rate is limited due to th

46、e scanning. They are therefore less suitable to capture fast processes than FPA-cameras.6.5 Working wavelength rangeThe working wavelength range depends on the detectors material, objective lens and encapsulating window. For testing, it is selected according to the test condition and test object. IS

47、O 2017 All rights reserved 3BS ISO 18251-1:2017ISO 18251-1:2017(E)6.6 Number of pixelsA two-dimensional detector array typically consists of a rectangular array of sensors or elements. For a detector of M rows and N columns, the number of pixels is M N. The number of pixels directly affects spatial

48、resolution of the infrared camera.6.7 Bad/dead pixelA bad/dead pixel is a detector element that does not respond or responds slowly to changes in radiation intensity. Imaging systems may incorporate algorithms to provide data to replace signals from bad/dead pixels.6.8 Detector operabilityDetector o

49、perability represents the percentage of individual sensors delivering a proper and usable electrical signal.6.9 Thermal time constantAs thermal detectors have a thermal capacity, they need a distinct time to respond to changes in radiation intensity. The thermal time constant for thermal detectors is the time required to change its body temperature by 63,2 % of a specific temperature span when the measurements are made under zero-power conditions in thermally stable environments. This is especially relevant in sy