1、Laser display devicesPart 5-2: Optical measuring methods of speckle contrastBS IEC 62906-5-2:2016BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National forewordThis British Standard is the UK implementation of IEC 62906-5-2:2016.The UK participation in its preparat
2、ion was entrusted to TechnicalCommittee EPL/47, Semiconductors.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions ofa contract. Users are responsible for its correct application. T
3、he British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 86280 9ICS 31.260Compliance 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 Jun
4、e 2016.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS IEC 62906-5-2:2016IEC 62906-5-2 Edition 1.0 2016-06 INTERNATIONAL STANDARD Laser display devices Part 5-2: Optical measuring methods of speckle contrast INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31.260 ISBN
5、 978-2-8322-3455-6 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. colourinsideBS IEC 62906-5-2:2016 2 IEC 62906-5-2:2016 IEC 2016 CONTENTS FOREWORD . 4 1 Scope 6 2 Normative references. 6 3 T
6、erms, definitions and abbreviations 6 3.1 Terms and definitions 6 3.2 Abbreviations 6 4 Standard measuring conditions 7 4.1 General . 7 4.2 Standard measuring environmental conditions . 7 4.3 Measurement coordinate system . 7 4.4 Darkroom conditions . 8 4.5 Standard conditions of measuring equipment
7、 . 8 4.5.1 General . 8 4.5.2 Adjustment of LDD . 9 4.5.3 Conditions of measuring equipment 9 4.6 Screen conditions . 10 4.6.1 General . 10 4.6.2 Report . 10 5 Measuring methods of speckle contrast 10 5.1 Speckle contrast measurement of still image 10 5.1.1 Purpose . 10 5.1.2 Measuring conditions . 1
8、0 5.1.3 Measuring the monochromatic speckle contrast of front projection 10 5.1.4 Measuring the monochromatic speckle contrast of rear projection . 12 5.2 Calibration and diagnosis of the LMD . 12 5.2.1 General . 12 5.2.2 Calibration procedure and diagnosis for the highest Cs. 13 5.2.3 Calibration p
9、rocedure and diagnosis for the lowest Cs13 Annex A (informative) Spectral behaviour of the LD 15 A.1 Spectral behaviour of a single-longitudinal mode LD 15 A.2 Spectral behaviour of a multi-longitudinal mode LD 15 Annex B (informative) Recommendation on imaging sensor pixel size . 16 Annex C (inform
10、ative) Fundamental formulation of speckle contrast and the effects of measurement variables 18 C.1 Fundamental formulation . 18 C.2 Effect of observation distance and iris radius . 18 Annex D (informative) Possible errors and their sources . 20 Bibliography . 21 Figure 1 Coordinate system for projec
11、tion direction and viewing direction 8 Figure 2 Example of measurement geometries for monochromatic speckle contrast of front projection 11 Figure 3 Example of measurement geometries for monochromatic speckle contrast of rear projection 12 Figure 4 Example of measurement geometries for Cscalibration
12、 . 13 BS IEC 62906-5-2:2016IEC 62906-5-2:2016 IEC 2016 3 Figure A.1 Example of spectral behaviour of a single-longitudinal mode LD . 15 Figure A.2 Example of spectral behaviour of a multi-longitudinal mode LD 15 Figure B.1 Minimum subjective speckle grain size as a function of the F-number . 17 Figu
13、re C.1 Measurement result of Csby changing NAscreen-Iris. 19 Table B.1 Example of ssubj16 BS IEC 62906-5-2:2016 4 IEC 62906-5-2:2016 IEC 2016 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ LASER DISPLAY DEVICES Part 5-2: Optical measuring methods of speckle contrast FOREWORD 1) The International Electr
14、otechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. T
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23、s IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of thi
24、s IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 62906-5-2 has been prepared by IEC technical committee 110: Electronic display devices. The text of this standard is based on the followi
25、ng documents: FDIS Report on voting 110/760/FDIS 110/768/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 ISO/IEC Directives, Part 2. A list of all parts in
26、 the IEC 62906 series, published under the general title Laser display devices, can be found on the IEC website. BS IEC 62906-5-2:2016IEC 62906-5-2:2016 IEC 2016 5 The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC webs
27、ite under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. IMPORTANT The “colour inside” logo on the
28、 cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this publication using a colour printer. BS IEC 62906-5-2:2016 6 IEC 62906-5-2:2016 IEC 2016 LASER DISPLAY DEVICES Part 5-2
29、: Optical measuring methods of speckle contrast 1 Scope This part of IEC 62906 specifies the standard measurement conditions and measurement methods for determining the monochromatic speckle contrast of laser display devices (LDDs). The LDDs may include hybrid types using both a laser or lasers, and
30、 spontaneous emission-based light sources, such as LEDs. NOTE The monochromatic speckle contrast measurements do not include image quality issues. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its applicatio
31、n. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60825-1, Safety of laser products Part 1: Equipment classification and requirements IEC 62906-1-2:2015, Laser display devices Part 1-
32、2: Vocabulary and letter symbols 3 Terms, definitions and abbreviations For the purposes of this document, the terms and definitions given in IEC 62906-1-2, as well as the following apply. 3.1 Terms and definitions 3.1.1 fully developed speckle FDS speckle when the speckle contrast ratio is equal to
33、 one (Cs = 1) SOURCE: Goodman:2006 113.2 Abbreviations DN digital number DUT device under test LD laser diode LMD light measuring device MTF modulation transfer function NA numerical aperture PPUT projection plane under test PSF point spread function _ 1Numbers square brackets refer to the bibliogra
34、phy. BS IEC 62906-5-2:2016IEC 62906-5-2:2016 IEC 2016 7 SNR signal to noise ratio 4 Standard measuring conditions 4.1 General An LDD is featured by using coherent or partially-coherent light sources. Speckle is created particularly by coherence of the light sources. Therefore, measuring methods and
35、equipment particularly designed for speckle are necessary. When carrying out optical measurements of LDD, the measuring environment, equipment and methods shall be compliant with IEC 60825-1 for human safety. 4.2 Standard measuring environmental conditions Optical measurements related to speckle sha
36、ll be carried out under the standard environmental conditions, at a temperature of 25 C 3 C, a relative humidity of 25 % to 85 %, and pressure of 86 kPa to 106 kPa. When different environmental conditions are used, they shall be noted in the report. 4.3 Measurement coordinate system The projection d
37、irection is the direction of a beam coming from the LDD to the projection plane under test (PPUT). The projection direction is defined by two angles: the angle of inclination (relative to the surface normal of the PPUT) and the angle of rotation (also called azimuth angle) as illustrated in Figure 1
38、 a). Although the azimuth angle is measured in the counter-clockwise direction, it is related to the directions on a clock face as follows: = 0 is the 3 oclock direction (“right“), = 90 the 12 oclock direction (“top“), = 180 the 9 oclock direction (“left“) and = 270 the 6 oclock direction (“bottom“)
39、. The viewing direction is the direction under which the observer looks at the point of interest on the device under test (DUT), including the projection plane under test (PPUT). During the measurement, the light-measuring device (LMD) simulates the observer, by aiming the LMD at the point of intere
40、st on the DUT from the viewing direction. The viewing direction is defined by two angles: the angle of inclination (relative to the surface normal of the DUT) and the angle of rotation (also called azimuth angle) as illustrated in Figure 1. Although the azimuth angle is measured in the counter-clock
41、wise direction, it is related to the directions on a clock face as follows: = 0 is the 3 oclock direction (“right“), = 90 the 12 oclock direction (“top“), = 180 the 9 oclock direction (“left“) and = 270 the 6 oclock direction (“bottom“). BS IEC 62906-5-2:2016 8 IEC 62906-5-2:2016 IEC 2016 a) PPUT (s
42、creen) for front projection b) PPUT (screen) for front projection, or DUT (LDD) for rear projection Figure 1 Coordinate system for projection direction and viewing direction 4.4 Darkroom conditions The LDD should be measured under controlled lighting conditions. Unwanted background illumination exce
43、pt the light generated by the LDD itself shall be minimized, typically by illuminating the display in a darkroom. The darkroom luminance contribution from the background illumination, which is the measurement illumination reflected off the DUT, shall be 1/20 of the lowest black level of the display.
44、 If this condition is not satisfied, then background subtraction is required and it shall be noted in the report. It is recommended that the background for each pixel of the imaging device be subtracted. In addition, if the sensitivity of the LMD is inadequate to measure at these low levels, then th
45、e lower limit of the LMD shall be noted in the report. Unless stated otherwise, the standard background lighting conditions shall be the darkroom conditions. 4.5 Standard conditions of measuring equipment 4.5.1 General It is assumed that all measurements are performed by personnel skilled in the gen
46、eral art of radiometric and electrical measurements as the purpose of this standard is not to give a detailed account of good practice in electrical and optical experimental physics. Furthermore, it is necessary to ensure that all equipment is suitably calibrated as is known to skilled personnel and
47、 that records of the calibration data and traceability are kept. It is assumed that all measurements are performed under normal operation conditions as used in the finished product by the end user unless requested otherwise. Standard equipment conditions are given below. Any deviations from these co
48、nditions shall be noted in the report. Measurements shall be started after the LDD, the light source, and measuring instruments achieve stability. If the measurement is not carried out under the darkroom conditions, depending on the application, the illumination/detection geometry and the light sour
49、ce spectral behaviour shall be reported. IEC Z Z Y Y X X 12:00 9:00 6:00 3:00 12:00 9:00 6:00 3:00 DUT (LDD) LMD or human eye BS IEC 62906-5-2:2016IEC 62906-5-2:2016 IEC 2016 9 4.5.2 Adjustment of LDD The LDD shall be measured at the factory default mode. The LDD may be also measured at additional modes (e.g. bright or movie mode). 4.5.3 Conditions of measuring equipment The speckle contrast created by the LDD shall
