1、BS EN 16782:2016Conservation of culturalheritage Cleaning of porousinorganic materials Lasercleaning techniques for culturalheritageBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN 16782:2016 BRITISH STANDARDNational forewordThis British Standard is the UK imple
2、mentation of EN 16782:2016.Use of this standard or any supporting documentation does not ofitself ensure compliance with statutory artificial optical radiationprotection requirements in the various EU member states.The European Agency for Safety and Health at Work (EU-OSHA) publish a non-binding gui
3、de to good practice forimplementing Directive 2006/25/EC - artificial optical radiation, which may be used to provide a minimum requirement ofthe directive. Individual member states may impose conditions whichexceed the minimum. In the UK, the Health and Safety Executive is the enforcing body for th
4、e statutory instrument The Control of Artificial Optical Radiation (AOR) at Work Regulations 2010. The information contained within EN 60825-1:2014 may also be ofrelevance to users.The UK participation in its preparation was entrusted to TechnicalCommittee B/560, Conservation of tangible cultural he
5、ritage.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016. Published by BSI S
6、tandardsLimited 2016ISBN 978 0 580 87205 1ICS 97.195Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 June 2016.Amendments/corrigenda issued since publicationDate
7、 T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 16782 May 2016 ICS 97.195 English Version Conservation of cultural heritage - Cleaning of porous inorganic materials - Laser cleaning techniques for cultural heritage Conservation du patrimoine culturel - Nettoyage des matr
8、iaux inorganiques poreux - Techniques de nettoyage au laser des biens culturels Erhaltung deskultreln Erbes -Reingu vonporsen anorganischen Materialien - Laserstrahlreinigungsverfahren fr kulturelles Erbe This European Standard was approved by CEN on 27 February 2016. CEN members are bound to comply
9、 with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC M
10、anagement Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
11、 status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg,
12、Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016
13、 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16782:2016 EBS EN 16782:2016EN 16782:2016 (E) 2 Contents Page European foreword . 3 Introduction 4 1 Scope 5 2 Normative references 5 3 Terms and definitions . 5 4 Symbols and abbrev
14、iations . 8 5 Key features of the laser system with respect to the cleaning of porous inorganic materials 9 5.1 General 9 5.2 Wavelength 9 5.3 Laser pulse duration 9 5.4 Regime of pulsed emission 9 5.5 Stability of laser emission . 10 5.6 Transmission system of the radiation 10 5.7 Handpiece . 10 5.
15、8 Irradiated area 10 5.9 Targeting system 10 6 Preliminary cleaning tests for selecting laser operating parameters 10 6.1 General . 10 6.2 Working fluence . 11 6.3 Working spot size . 13 6.4 Repetition rate 13 7 Cleaning test report . 13 7.1 Laser instrument 13 7.2 Preliminary tests for selecting la
16、ser operating parameters 14 Annex A (informative) Measurement of the ablation curve 15 Annex B (informative) Optical absorption . 16 Annex C (informative) Duration of laser pulse . 17 Annex D (informative) Role of water . 18 Annex E (informative) Repetition frequency 19 Annex F (informative) Reflect
17、ance measurement 20 Annex G (informative) Possible harmful effects of laser cleaning on objects . 21 Annex H (informative) Health and safety . 22 Bibliography . 23 BS EN 16782:2016EN 16782:2016 (E) 3 European foreword This document (EN 16782:2016) has been prepared by Technical Committee CEN/TC 346
18、“Conservation of cultural heritage”, the secretariat of which is held by UNI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2016, and conflicting national standards shall be withdrawn a
19、t the latest by November 2016. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. WARNING This standard calls for the use of procedures t
20、hat can be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. According to the CEN/CENELEC Internal Regulations, the national standards organizations of th
21、e following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherl
22、ands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 16782:2016EN 16782:2016 (E) 4 Introduction A cleaning method can be applied out if it follows the ethical code of conservation practice as stated in International Charters. L
23、aser cleaning consists in the removal of the unwanted surface materials from a substrate by using laser irradiation. The removal of unwanted substances on surfaces of artworks is done by photo-thermal processes and/or photomechanical processes, and/or photochemical processes. Laser cleaning is gener
24、ally characterized by a high precision and selectivity, which may allow the process to be stopped at a pre-determined level. Laser cleaning requires very precise control to be selective and prevent surface damage. As with other cleaning systems, laser cleaning can only be performed by trained operat
25、ors with sufficient knowledge of all relevant laser safety regulations and guidelines. This standard specifies the requirements for the selection of laser cleaning methods and devices applicable to natural stone, ceramics and mortars (plasters, renders and stucco). When it is not possible to identif
26、y a safe working fluence (for example for certain stone lithologies or some painted artworks containing sensitive materials), laser cleaning is not suitable. BS EN 16782:2016EN 16782:2016 (E) 5 1 Scope This European standard applies to porous inorganic materials constituting cultural heritage. It pr
27、ovides the fundamental requirements of the laser parameters and guidelines for the choice of the laser operational parameters, in order to optimize the cleaning procedure. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispe
28、nsable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 15898:2011, Conservation of cultural property Main general terms and definitions EN 16572:2015, Conservation
29、of cultural heritage Glossary of technical terms concerning mortars for masonry, renders and plasters used in cultural heritage 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 15898:2011, EN 16572:2015 and the following apply. 3.1 cleaning removal of
30、unwanted material from an object Note 1 to entry: The criteria for something being “unwanted” can always be stated, e.g. potentially damaging, obscuring detail, unaesthetic, etc. SOURCE: EN 15898:2011, 3.5.3 3.2 mortar material traditionally composed of one or more (usually inorganic) binders, aggre
31、gates, water, possible additives and admixtures combined to form a paste used in masonry to provide for bedding, jointing and bonding, and for surface finishing (plastering and rendering) of masonry units, which subsequently sets to form a stiff material SOURCE: EN 16572:2015, 3.1.1 3.3 plaster coat
32、ing composed of one or more mortar layers applied in one accomplishment sequence, used on internal masonry surface such as ceiling, walls, and partition Note 1 to entry: Plaster is a traditional English term. SOURCE: EN 16572:2015, 3.2.5 BS EN 16782:2016EN 16782:2016 (E) 6 3.4 render coating compose
33、d of one or more mortar layers applied in one accomplishment sequence, used on external masonry surfaces and which has protection function and surface finishing Note 1 to entry: Render(ing) is a traditional English term. SOURCE: EN 16572:2015, 3.2.6 3.5 stucco mortars used for making decorative moul
34、dings, architectural castings and other decorations on the facades and in the interiors of the buildings SOURCE: EN 16572:2015, 3.2.8 3.6 laser Light Amplification by Stimulated Emission of Radiation radiation source that generates a coherent, monochromatic and very powerful beam of light in the ran
35、ge of ultraviolet, visible or infrared wavelengths 3.7 laser ablation removal of material from an object induced by the laser radiation absorption, in the form of molecular radicals, vapours and particles of different sizes 3.8 photo thermal ablation ablation process caused by heat generated by the
36、laser radiation absorption 3.9 photo mechanical ablation ablation process caused by mechanical stress and strains induced by the laser radiation absorption 3.10 photo chemical ablation ablation process caused by chemical bond cleavages induced by the laser radiation absorption 3.11 light radiation t
37、hat is considered from the point of view of its ability to excite the visual system Note 1 to entry: It corresponds to the so-called visible radiation in the range between 380 nm and 780 nm. Note 2 to entry: In the field of conservation, this term sometimes extends the range outside the visible port
38、ion, including parts of the ultraviolet (UV) and near infrared (IR) regions. SOURCE: CIE S 017/E:2011 BS EN 16782:2016EN 16782:2016 (E) 7 3.12 infrared radiation part of the electromagnetic spectrum with wavelength longer than those of the visible radiation, from about 780 nm to tens of micrometres
39、SOURCE: CEN/TS 16163:2014, 3.18) 3.13 ultraviolet radiation part of the electromagnetic spectrum with wavelengths from 10 nm to 380 nm SOURCE: CEN/TS 16163:2014, 3.36 3.14 irradiated area spot area of the object subject to the laser beam during one single shot, in cm23.15 laser fluence amount of ene
40、rgy divided by the irradiated area, in joules per square centimetre (J/cm2) Note 1 to entry: The energy density can be changed at the sample surface if lenses are placed in the path of the laser beam. 3.16 power density power divided by the irradiated surface, in watt per square centimeter (W/cm2) 3
41、.17 laser continuous wave emission CW emission stationary emission of a radiation laser at a constant power, in which the interaction of the laser beam and a surface is largely thermal 3.18 average power for laser continuous wave emission energy emitted by a laser in one second, in watts (W) 3.19 la
42、ser pulsed emission mode of laser emission consisting of successive temporal pulses having a constant duration and characterized by an instantaneous power (see 3.16) much higher than the average power. Note 1 to entry: In pulse mode, the interaction of the laser beam and a surface is commonly believ
43、ed to be a combination of thermal and mechanical processes. 3.20 peak power single pulse energy divided by the duration of the pulse, in watts (W) 3.21 average power for laser pulsed emission result of multiplication of pulse energy by the repetition rate, in watts (W) BS EN 16782:2016EN 16782:2016
44、(E) 8 3.22 pulse duration Full Width Half Maximum, or width at which the pulse energy/power is half that of the maximum energy/power Note 1 to entry: The duration of a pulse from a laser is a key factor in determining how the light will interact with material. Pulse durations range from “ultra short
45、” femto seconds (1015s) to “long pulse” micro seconds (106s). Note 2 to entry: This definition refers to how “pulse duration” is usually defined. 3.23 laser repetition rate number of pulses per second, in hertz (Hz) 3.24 reflectance ratio between the light intensity reflected by a surface and the in
46、cident light on the same surface, in percentage (%) 3.25 depth of optical penetration (into the material) distance measured from the surface coincident with the reduction of the intensity of incident light radiation equivalent to 1/e and by means of absorption (e 2,7) 3.26 Q-switched laser laser gen
47、erally having a pulse width in the range 5 to 30 ns, put to use by the technique of q-swithching that is used to produce a pulsed output laser beam, allowing the emission of pulses with extremely high peak power 3.27 free running laser laser in which the emission lasts as long as the pumping process
48、 is sufficient to sustain lasting condition Note 1 to entry: Typical pulse durations are in the range of s-ms. 3.28 laser ablation fluence threshold AFthlowest fluence that causes ablation of the material to be removed 3.29 laser damage fluence threshold DFthlowest fluence that causes unwanted chang
49、es to the material to be preserved 4 Symbols and abbreviations FLlaser fluence Fth threshold fluence AFth laser ablation fluence threshold BS EN 16782:2016EN 16782:2016 (E) 9 Fth(A) threshold fluence at point A (beginning of ablation of layer A) Fth(B) threshold fluence at point B is the damage threshold fluence DFthDFthlaser damage fluence thresold Flimthreshold fluence limit CW continuous wave QS Q-Switched FR free running SFR short free running mablamount of material removed for each laser pulse Fth(sat)threshold fluence corresponding to the s
