IEC 62906 1 2 Edition 1 0 201 5 07 INTERNATIONAL STANDARD Laser display devices – Part 1 2 Vocabulary and letter symbols IE C 6 2 9 0 6 1 2 2 0 1 5 0 7 (e n ) ® colour inside Copyright International E[.]
I E C 62 6-1 -2 ® Edition 201 5-07 I N TE RN ATI ON AL S TAN D ARD colour i n sid e Las er d i s pl ay d e vi ce s – IEC 62906-1 -2:201 5-07(en) P art -2 : Vocabu l ary an d l e tter s ym bol s T H I S P U B L I C AT I O N I S C O P YRI G H T P RO T E C T E D C o p yri g h t © I E C , G e n e v a , S wi tz e rl a n d All rights reserved Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or IEC's member National Committee in the country of the requester If you have any questions about I EC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local I EC member National Committee for further information IEC Central Office 3, rue de Varembé CH-1 21 Geneva 20 Switzerland Tel.: +41 22 91 02 1 Fax: +41 22 91 03 00 info@iec.ch www.iec.ch Ab ou t th e I E C The I nternational Electrotechnical Commission (I EC) is the leading global organization that prepares and publishes I nternational Standards for all electrical, electronic and related technologies Ab o u t I E C p u b l i ca ti o n s The technical content of IEC publications is kept under constant review by the IEC Please make sure that you have the latest edition, a corrigenda or an amendment might have been published I E C Catal og u e - webstore i ec ch /catal og u e The stand-alone application for consulting the entire bibliographical information on IEC International Standards, Technical Specifications, Technical Reports and other documents Available for PC, Mac OS, Android Tablets and iPad I E C pu bl i cati on s s earch - www i ec ch /search pu b The advanced search enables to find IEC publications by a variety of criteria (reference number, text, technical committee,…) It also gives information on projects, replaced and withdrawn publications E l ectroped i a - www el ectroped i a org The world's leading online dictionary of electronic and electrical terms containing more than 30 000 terms and definitions in English and French, with equivalent terms in additional languages Also known as the International Electrotechnical Vocabulary (IEV) online I E C G l os sary - s td i ec ch /g l oss ary More than 60 000 electrotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002 Some entries have been collected from earlier publications of IEC TC 37, 77, 86 and CISPR I E C J u st Pu bl i s h ed - webstore i ec ch /j u stpu bl i sh ed Stay up to date on all new IEC publications Just Published details all new publications released Available online and also once a month by email I E C C u stom er S ervi ce C en tre - webstore i ec ch /csc If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csc@iec.ch I E C 62 6-1 -2 ® Edition 201 5-07 I N TE RN ATI ON AL S TAN D ARD colour i n sid e Las er d i s pl ay d e vi ces – P art -2 : Vocabu l ary an d l e tte r s ym bol s INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31 260 ISBN 978-2-8322-2779-4 Warn i n g ! M ake su re th a t you obtai n ed th i s pu bl i cati on from an au th ori zed d i s tri bu tor ® Registered trademark of the International Electrotechnical Commission –2– I EC 62906-1 -2: 201 © I EC 201 CONTENTS FOREWORD Scope Terms, definitions, and abbreviations Classification of term s 2 Fundam ental terms Terms related to speckle Terms related to display category Terms related to optical devices Terms related to light sources Letter symbols (quantity symbols / unit sym bols) Annex A (informative) Categorization of speckle and speckle contrast ratio A Objective speckle A Subj ective speckle A Speckle contrast ratio Bibliograph y Figure A – Optical configuration to observe objective speckle Figure A – Optical configuration to observe subjective speckle Figure A – Classification m ap of speckle Table – Letter symbols I EC 62906-1 -2: 201 © I EC 201 –3– INTERNATI ONAL ELECTROTECHNI CAL COMMI SSION L AS E R D I S P L AY D E VI C E S – P a rt -2 : Vo c a b u l a ry a n d l e tte r s ym b o l s FOREWORD ) The I nternati on al Electrotechni cal Comm ission (I EC) is a worl d wid e organization for stan dardization com prisin g all n ation al el ectrotechnical comm ittees (I EC National Comm ittees) The object of I EC is to prom ote internati onal co-operation on all questions concerni ng stand ardi zati on in the el ectrical an d electronic fields To this end and in additi on to other acti vities, I EC publish es I nternational Stan dards, Techn ical Specifications, Technical Reports, Publicl y Avail abl e Specificati ons (PAS) an d Gu ides (h ereafter referred to as “I EC Publication(s)”) Thei r preparation is entrusted to technical comm ittees; any I EC National Comm ittee interested in the subj ect dealt with m ay partici pate in this preparatory work I nternational, governm ental an d n on governm ental organ izations l iaising with th e I EC also participate i n this preparation I EC collaborates closel y with the I ntern ational Organi zation for Stand ardization (I SO) in accordance with conditions determ ined by agreem ent between th e two organi zati ons 2) The form al decisions or ag reem ents of I EC on tech nical m atters express, as n early as possible, an i nternati onal consensus of opi nion on the rel evant subjects since each technical com m ittee has representati on from all interested I EC N ational Com m ittees 3) I EC Publications have the form of recomm endations for intern ational use an d are accepted by I EC National Com m ittees in that sense While all reasonable efforts are m ade to ensure that th e technical content of I EC Publications is accu rate, I EC cann ot be h eld responsi ble for th e way in which th ey are used or for an y m isinterpretation by an y en d u ser 4) I n order to prom ote intern ational u niform ity, I EC National Com m ittees und ertake to apply I EC Publications transparentl y to the m axim um extent possible i n their national an d regi on al publicati ons Any d ivergence between an y I EC Publication and the correspondi ng national or regi on al publicati on sh all be clearl y in dicated in the latter 5) I EC itself d oes n ot provi de an y attestation of conform ity I n depend ent certificati on bodies provi de conform ity assessm ent services and, in som e areas, access to I EC m arks of conform ity I EC is not responsi ble for any services carri ed out by ind ependent certification bodi es 6) All users shou ld ensure that th ey have the l atest editi on of thi s publicati on 7) No liability shall attach to I EC or its directors, em ployees, servants or ag ents inclu din g in divi dual experts an d m em bers of its technical com m ittees and I EC Nati on al Com m ittees for any person al i njury, property d am age or other dam age of any nature whatsoever, wheth er di rect or indirect, or for costs (includ i ng leg al fees) and expenses arisi ng out of the publ ication, use of, or relian ce upon, this I EC Publicati on or any other I EC Publications 8) Attention is drawn to th e N orm ative references cited in th is publ ication Use of the referenced publ ications is indispensable for the correct applicati on of this publication 9) Attention is drawn to the possibility that som e of the elem ents of this I EC Publication m ay be the su bject of patent rig hts I EC shall not be held responsibl e for identifyi ng any or all such patent ri ghts I nternational Standard 62601 -1 -2 has been prepared by I EC technical comm ittee 1 0: Electronic display devices The text of this standard is based on the following docum ents: FDI S Report on votin g 1 0/661 /FDI S 1 0/672/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table This publication has been drafted in accordance with the I SO/I EC Directives, Part A list of all parts in the I EC 62906 series, published under the general title Laser display devices , can be found on the I EC website –4– I EC 62906-1 -2: 201 © I EC 201 The committee has decided that the contents of this publication will rem ain unchanged until the stability date indicated on the I EC website under "http: //webstore iec ch" in the data related to the specific publication At this date, the publication will be • • • • reconfirm ed, withdrawn, replaced by a revised edition, or amended A bilingual version of this publication may be issued at a later date I M P O RT AN T th a t it – Th e co n ta i n s u n d e rs t a n d i n g c o l o u r p ri n t e r of ' co l ou r c o l o u rs i ts i n si de' wh i ch c o n te n ts l og o a re U s e rs on th e cover c o n s i d e re d sh ou l d p ag e to t h e re fo re of th i s be p ri n t p u b l i cati o n u s e fu l th i s fo r i n d i cate s th e d ocu m e n t c o rre c t u si n g a I EC 62906-1 -2: 201 © I EC 201 –5– L AS E R D I S P L AY D E VI C E S – P a rt -2 : Vo c a b u l a ry a n d l e tte r s ym b o l s S cop e This part of I EC 62906 gives the preferred terms, their definitions and symbols for laser display devices and relevant com ponents with the object of using the same terminolog y when publications are prepared in different countries T e rm s , d e fi n i t i o n s , a n d a b b re vi a t i o n s For the purposes of this docum ent, the following terms and definitions apply C l a s s i fi c a t i o n o f t e rm s Term s for laser display devices and relevant components are classified as follows: a) b) c) d) e) fundam ental terms; term s related to speckle; term s related to display category; term s related to optical devices; terms related to light sources 2 F u n d am en tal t e rm s 2 l a s er d i s p l a y d evi ce LDD display device using a laser or lasers, based on stimulated em ission 2 h yb ri d l a s er d i s p l a y d e vi c e h yb ri d L D D h -L D D display device using both a laser or lasers and spontaneous em ission-based light sources T e rm s re l a t e d t o s p e c k l e s p e c kl e < laser display devices > irregularl y aligned spatiall y-m odulated image created by coherent or partiall y coherent lights as a result of interference on a sensor plane of the visual sensory system of the observer Note to entry: For a hum an observer, the sensor plane of the visual sensory system is the reti na of th e eye m o n o c h ro m a t i c s p e c kl e speckle when the light source is monochrom atic or quasi-monochromatic 3 col ou r s p eckl e speckle when the light source is m ulti-coloured –6– I EC 62906-1 -2: 201 © I EC 201 2.3.4 speckle pattern illum inance distribution of speckle 2.3.5 speckle contrast ratio speckle contrast SCR Cs ratio of the illuminance standard deviation to the average of the speckle pattern in the m easurement field Note to entry: See Cl ause A for further inform ation [SOU RCE: J W GOODMAN , Speckle Phenomena in Optics: Theory and Applications (Roberts and Compan y Publishers, Colorado, 2006)] 2.3.6 signal to noise ratio < speckle-oriented noise > inverse of the speckle contrast ratio 2.3.7 objective speckle speckle observed by an optical sensory system without imaging optics Note to entry: See Cl ause A for further inform ation [SOU RCE: M KURASHI GE et al., The evaluation of speckle contrast with variable speckle generator, J Soc I nfo Display 9/9, 631 -638 (201 )] 2.3.8 subjective speckle speckle observed by a visual sensory system with im aging optics Note to entry: See Cl ause A for further inform ation [SOU RCE: M KURASHI GE et al., The evaluation of speckle contrast with variable speckle generator, J Soc I nfo Display 9/9, 631 -638 (201 )] 2.3.9 projected speckle subj ective speckle arising from a proj ected interference pattern created by coherent or partiall y coherent light on a screen Note to entry: See Cl ause A for further inform ation [SOU RCE: M KURASHI GE et al., “ Classification of subjective speckle for evaluation of laser display”, SI D Sym posium Digest 45, 41 9-422 (201 4)] 2.3.1 screen speckle subj ective speckle arising from the scattering or diffusion of coherent or partiall y coherent light on a screen Note to entry: See A for furth er i nform ation [SOU RCE: M KURASHI GE et al., “ Classification of subjective speckle for evaluation of laser display”, SI D Sym posium Digest 45, 41 9-422 (201 4)] I EC 62906-1 -2: 201 © I EC 201 –7– 1 speckl e g rain size spacing of interference fringes generated by coherent or partial coherent beam s on a sensor plane of a visual sensory system imu m obj ective speckl e g rai n size s obj m inim um spacing of interference fringes which is determined by the interference of two coherent beams from the opposite edges of the illuminated area to the sensor plane Note to entry: See Cl ause A for further inform ation 3 i mu m su bj ecti ve speckl e g rain size s su bj m inimum spacing of interference fringes which is determ ined by the interference of two coherent beams from the opposite edges of the effective diameter of imagi ng optics to the sensor plane Note to entry: See Cl ause A for further inform ation Term s rel ated to d i spl ay categ ory raster-scan n ed proj ecti on image projection (on a screen or a proj ection plane) by raster-scanning laser beams fu l l-fram e proj ection image projection (on a screen or a proj ection plane) by a 2D spatial light modulator li n e-scan n ed proj ection image proj ection (on a screen or a projection plane) by a combination of a D spatial light modulator and a D optical scanner 4 fron t proj ection image projection (on a screen or a proj ection plane) from the sam e side as the observer rear proj ection im age proj ection (on a screen or a projection plane) from the side opposite to that of the observer reti n a di rect proj ection image projection directl y on the retina Term s rel ated to opti cal d evi ces screen proj ecti on screen proj ecti on pl an e plane on which an im age is projected and observed as diffused light –8– I EC 62906-1 -2: 201 © I EC 201 2.5.2 liquid crystal on silicon LCOS spatial light m odulator to create images, based on liquid crystal fabricated on a silicon wafer 2.5.3 digital mirror device digital micromirror device DMD spatial light modulator to create images by switching a Micro Electro Mechanical System s (MEMS) mirror array 2.6 Terms related to light sources 2.6.1 second harmonic generation laser SHG laser coherent or partiall y coherent light source of which photon energ y is up-converted to twice that of the pum p laser through the second harmonic generation process Letter symbols (quantity symbols / unit symbols) See Table Table – Letter symbols Cs s obj s su bj Speckle contrast ratio Min im um objective speckle g rain size (m ) Min im um subjective speckle grain size (m ) I EC 62906-1 -2: 201 © I EC 201 –9– Annex A (informative) Categorization of speckle and speckle contrast ratio A.1 Objective speckle Objective speckle is recognized as a speckle pattern on a sensor plane without an y imaging optics Figure A shows an optical configuration for explaining obj ective speckle and its sensing method I n this case, a sensor array is sim ply set at the sensor plane Laser beam Sensor plan e θob j I llum inated area Sensor array Screen IEC Figure A.1 – Optical configuration to observe objective speckle The structure of obj ective speckle depends on the surface state of the screen, the illum inated area on the screen, and the distance between the screen and the sensor plane Minimum obj ective speckle grain size s obj is defined as the minimum spacing of interference fringes generated by interference of two coherent beams from the opposite edges of the illuminated area Minim um obj ective speckle grain size, s obj is obtained by the following equation s obj = λ sin θ obj (A ) where λ θobj is the wavelength of the coherent beam ; is the half-angle between two coherent beam s from opposite edges of the illuminated area The size of the illuminated area and the distance between the sensor array and the screen should be carefull y chosen to resolve the objective speckle structure sufficientl y A.2 Subjective speckle Subj ective speckle is recognized as a speckle pattern on a sensor plane through im aging optics An optical configuration for explaining the subj ective speckle and its sensing method is shown in Figure A I n this case, a cam era, implying an im aging system consisting of the sensor array and imaging lenses, is used as a sensing device For sim plicity, a single-lens system represents the im aging system in Figure A The minimum speckle structure depends on localized surface structure of the screen and the angular aperture of im aging lens Therefore, m inimum subj ective speckle grain size s subj is – 10 – I EC 62906-1 -2: 201 © I EC 201 defined as the m inim um spacing of interference fringes which is determined by interference of two coherent beam s from the opposite edges of the angular aperture Minimum subjective speckle grain size, s su bj is obtained by the following equation s subj = λ sin θ subj (A 2) where λ θsubj is the wavelength of the coherent beam ; is the half-angle between two coherent beam s from opposite edges of the effective diam eter of the imaging lens at im age space Unlike in the case of obj ective speckle, minimum subj ective speckle grain size is not dependent on the illuminated area on the screen or the distance from the screen, but on angular aperture of the image space Therefore, the aperture size, focal length of imaging lens and pixel size of the sensor array should be carefull y chosen to resolve the structure of subj ective speckle clearly Laser beam Cam era I m aging lens θsu b j I llum inated area Sensor plane Sensor array Angul ar aperture of im age space Screen IEC Figure A.2 – Optical configuration to observe subjective speckle Subj ective speckle is classified into two types according to its generation mechanism Figure A shows a classification m ap of speckle Speckle Objecti ve speckle Subjecti ve speckle m easured by n on -im aging opti cal m easuring m ethod m easured by im agin g optical measuring m ethod Projected speckle ori ginated from the displ ay u nit Screen speckle ori ginated from the screen IEC Figure A.3 – Classification map of speckle A.3 Speckle contrast ratio As a m easurem ent parameter of speckle, speckle contrast ratio Cs is introduced and defined as: I EC 62906-1 -2: 201 © I EC 201 – 11 – Cs = σ I (A 3) where σ is the standard deviation of the speckle pattern; I is the average of the speckle pattern Speckle contrast ratio Cs is in general calculated using the illuminance distribution of the captured im age, and applicable only to m onochromatic speckle – 12 – I EC 62906-1 -2: 201 © I EC 201 Bibliography [1 ] I EC 60050 (all parts), International at < http: //www electropedia org > ) [2] J.W GOODMAN, Speckle Phenomena in Optics: Theory and Applications (Roberts and Com pan y Publishers, Colorado, 2006) [3] M KURASHI GE et al., The evaluation of speckle contrast with variable speckle generator, J Soc I nfo Display 9/9, 631 -638 (201 ) [4] M KURASH I GE et al., Classification of subjective speckle for evaluation of laser display, SI D Sym posium Digest 45, 41 9-422 (201 4) Electrotechnical _ Vocabulary (available INTERNATIONAL ELECTROTECHNICAL COMMISSI ON 3, rue de Varembé PO Box 31 CH-1 21 Geneva 20 Switzerland Tel: + 41 22 91 02 1 Fax: + 41 22 91 03 00 info@iec.ch www.iec.ch