IEC 62906-5-4:2018

IEC 62906-5-4 ®
Edition 1.0 2018-01
INTERNATIONAL
STANDARD
colour
inside
Laser display devices –
Part 5-4: Optical measuring methods of colour speckle

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IEC 62906-5-4 ®
Edition 1.0 2018-01
INTERNATIONAL
STANDARD
colour
inside
Laser display devices –
Part 5-4: Optical measuring methods of colour speckle

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.260 ISBN 978-2-8322-5243-7

– 2 – IEC 62906-5-4:2018  IEC 2018
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, letter symbols and abbreviated terms . 7
3.1 Fundamental terms . 7
3.2 Terms related to colour speckle distribution . 7
3.3 Terms related to spatial variation . 8
3.4 Letter symbols . 8
3.5 Abbreviated terms . 9
4 Theory of colour speckle . 9
4.1 General . 9
4.2 Mechanism for generating colour speckle . 9
5 Calculation methods of colour speckle . 11
5.1 General . 11
5.2 Measuring method of spectral behaviour of BGR light sources . 12
5.3 Target chromaticity . 12
5.4 Adjustment of BGR power ratio . 14
5.5 Calculation method (a) using BGR speckle contrast C , C , C . 15
s-B s-G s-R
5.5.1 General . 15
5.5.2 Examples of measured distributions. 16
5.6 Evaluation metrics . 20
5.7 Calculation method (b) using the measured spatial distribution of BGR
monochromatic speckles . 21
5.7.1 General . 21
5.7.2 Examples of measured distributions. 21
5.7.3 Comparison between methods (a) and (b) . 23
5.7.4 Elimination of the background effects . 25
5.8 Error analysis based on data size . 28
6 Direct measuring methods of colour speckle . 32
6.1 General . 32
6.2 Fundamental design of LMD for colour speckle measurement . 33
6.3 Colour speckle measuring method using LMD with XYZ filters . 34
6.4 Colour speckle measuring method using LMD with BGR filters . 35
7 Measuring methods related to spatial variation . 36
7.1 General . 36
7.2 Angular colour speckle variation . 36
7.3 Photometric speckle contrast uniformity/non-uniformity . 37
7.4 Colour speckle variance/covariance non-uniformity . 38
Annex A (informative) Complementary explanation of colour speckle . 39
Annex B (informative) Examples of colour speckle distributions . 40
B.1 Colour speckle distributions (one of the BGR: 90 %, the others: 1 %) . 40
B.2 Colour speckle distributions (two of the BGR: 90 %, the other: 1 %). 43
Annex C (informative) Calibration of XYZ errors . 48
C.1 General . 48
C.2 Formulation of XYZ mismatches . 48

C.3 Calibration of the mismatched XYZ errors using the true BGR chromaticity
values . 50
Bibliography . 51

Figure 1 – Two speckle measuring methods and their flow charts . 12
Figure 2 – Target chromaticity and colour gamut . 13
Figure 3 – S (λ) with an FWHM of 2 nm. 13
B,G,R
Figure 4 – Adjustment method of BGR power ratio . 15
Figure 5 – Colour speckle distribution for C = 100 %, C = 100 %, C = 100 % . 16
s-B s-G s-R
Figure 6 – Photometric speckle distribution for C = 100 %, C = 100 %,
s-B s-G
C = 100 % . 17
s-R
Figure 7 – Colour speckle distribution for C = 50 %, C = 50 %, C = 50 % . 18
s-B s-G s-R
Figure 8 – Photometric speckle distribution for C = 50 %, C = 50 %, C = 50 % . 18
s-B s-G s-R
Figure 9 – Colour speckle distribution for C = 10 %, C = 10 %, C = 10 % . 19
s-B s-G s-R
Figure 10 – Photometric speckle distribution for C = 10 %, C = 10 %, C = 10 % . 20
s-B s-G s-R
Figure 11 – Colour speckle distribution for C = 9,2 %, C = 9,7 %, C = 9,2 %
s-B s-G s-R
obtained by method (b) . 22
Figure 12 – Colour speckle distribution for C = 9,2 %, C = 19,2 %, C = 23,2 %
s-B s-G s-R
obtained by method (b) . 23
Figure 13 – Colour speckle distribution for C = 9,2 %, C = 9,7 %, C = 9,2 %
s-B s-G s-R
obtained by method (a) . 24
Figure 14 – Colour speckle distribution for C = 9,2 %, C = 19,2 %, C = 23,2 %
s-B s-G s-R
obtained by method (a) . 24
Figure 15 – Raw data of BGR speckle distributions (upper row) and post-processed
data (lower row) for BGR monochromatic speckles (left: B, centre: G, right: R) . 26
Figure 16 – Colour speckle distribution directly using the raw data in Figure 15 . 26
Figure 17 – Colour speckle distribution for C = 16,2 %, C = 17,4 %, C = 17,3 %
s-B s-G s-R
obtained by indirect measuring method (a). 27
Figure 18 – Calculated average chromaticity values of the colour speckle distribution
with respect to data size for C = C = C = 80 % . 28
s-B s-G s-R
Figure 19 – Calculated average values of the normalized speckle illuminance speckle
distribution and the normalized monochromatic speckle intensity distribution with
respect to data size for C = C = C = 80 %. 29
s-B s-G s-R
Figure 20 – Calculated average chromaticity values of the colour speckle distribution
with respect to data size for C = C = C = 60 % . 29
s-B s-G s-R
Figure 21 – Calculated average values of the normalized speckle illuminance speckle
distribution and the normalized monochromatic speckle intensity distribution with
respect to data size for C = C = C = 60 %. 30
s-B s-G s-R
Figure 22 – Calculated average chromaticity values of the colour speckle distribution
with respect to data size for C = C = C = 40 % . 30
s-B s-G s-R
Figure 23 – Calculated average values of the normalized speckle illuminance speckle
distribution and the normalized monochromatic speckle intensity distribution with
respect to data size for C = C = C = 40 %. 31
s-B s-G s-R
Figure 24 – Calculated average chromaticity values of the colour speckle distribution
with respect to data size for C = C = C = 20 % . 31
s-B s-G s-R
Figure 25 – Calculated average values of the normalized speckle illuminance speckle
distribution and the normalized monochromatic speckle intensity distribution with
respect to data size for C = C = C = 20 %. 32
s-B s-G s-R
Figure 26 – Example of LMDs using XYZ filters for colour speckle measurement . 33

– 4 – IEC 62906-5-4:2018  IEC 2018
Figure 27 – Example of LMDs using BGR filters for colour speckle measurement . 34
Figure 28 – Example of measurement geometries for colour speckle using an LMD with
XYZ filters . 35
Figure 29 – Example of measurement geometries for colour speckle using an LMD with
BGR filters . 36
Figure 30 – Representation of the viewing direction, or direction of measurement,
ϕ ) in a
defined by the angle of inclination θ, and the angle of rotation (azimuth angle
polar coordinate system . 37
Figure A.1 – Photograph of colour speckle .
...