IEC 62595-2-4:2020

IEC 62595-2-4 ®
Edition 1.0 2020-09
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 2-4: Electro-optical measuring methods of laser module
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IEC 62595-2-4 ®
Edition 1.0 2020-09
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 2-4: Electro-optical measuring methods of laser module

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120, 31.260 ISBN 978-2-8322-8912-9

– 2 – IEC 62595-2-4:2020 © IEC 2020
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms, definitions, abbreviated terms, and letter symbols . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms and letter symbols . 11
3.2.1 Abbreviated terms . 11
3.2.2 Letter symbols . 12
4 Standard measuring conditions . 14
4.1 Standard measuring environmental conditions . 14
4.2 Standard measuring dark-room conditions . 14
4.3 Safety requirements . 14
4.4 Standard DUT conditions . 15
4.5 Standard LMD requirements . 15
4.6 Standard measurement setup and coordinate system . 17
5 Measuring methods . 20
5.1 General . 20
5.2 Current-light output characteristics . 21
5.2.1 General . 21
5.2.2 I-P and I- P / P characteristics . 21
o o i
5.2.3 CW and PWM operations . 22
5.2.4 Threshold currents (I ) . 23
th
5.2.5 Measurement procedures . 24
5.3 Spectra (wavelength) and chromaticity measurements . 25
5.3.1 General . 25
5.3.2 Measurement procedures . 25
5.4 FFP . 26
5.4.1 General . 26
5.4.2 Monochromatic FFP . 26
5.4.3 Colorimetric FFP . 27
5.5 Monochromatic speckle and colour speckle . 30
5.5.1 General . 30
5.5.2 Monochromatic speckle measurement affected by FFP . 30
5.5.3 Colour speckle measurement affected by FFP . 32
5.6 Temperature dependence . 35
5.6.1 General . 35
5.6.2 High-power LD module . 35
5.6.3 Low-power RGB LD module . 36
5.7 High-speed pulse modulation properties . 37
5.7.1 General . 37
5.7.2 Optical output pulse waveform measurement . 37
Annex A (informative) Laser devices . 40
A.1 Edge-emitting laser diode . 40
A.2 Single- and multi-transverse modes . 41
A.3 Single- and multi-longitudinal modes . 42

A.4 Vertical cavity surface-emitting laser diode (VCSEL) . 43
A.5 Photon up-conversion laser device. 45
Annex B (informative) Structure of laser module . 46
B.1 Monochromatic laser module . 46
B.2 RGB laser module . 47
B.3 Other output optics . 48
Annex C (informative) Narrow-linewidth emission spectra of laser modules . 49
C.1 Spectra of monochromatic high-power LD modules . 49
C.2 Spectra of multi-colour, single-longitudinal mode LD modules . 51
C.3 Spectra of multi-colour, multi-longitudinal mode LD modules . 51
C.4 Chromaticity measurements using a colorimeter . 52
Annex D (informative) Chromaticity accuracy when measuring narrow spectral
linewidth . 53
D.1 General . 53
D.2 Wavelength accuracy to keep chromaticity accuracy < 0,001 or < 0,005 . 53
D.3 Spectral bandwidth to keep chromaticity accuracy < 0,001 . 55
Annex E (informative) Numerical aperture (NA) of fibre . 58
E.1 Fibre NA and maximum divergence angle . 58
E.2 Colour-dependence of fibre NA . 58
Annex F (informative) Conversion of the spherical and Cartesian coordinate systems . 59
Annex G (informative) Centroid wavelength . 60
Annex H (informative) Examples of colour speckle pattern on colorimetric FFPs of
fibre output . 62
H.1 General . 62
H.2 Measured FFP . 62
Annex I (informative) Temperature dependence of LDs . 65
I.1 Formulation of the thermal performance of LD chips . 65
I.2 Calculated examples of I-P characteristics . 66
o
I.3 Temperature dependence of emitting wavelengths . 69
I.4 Temperature dependence of colour speckle and FFP . 69
Annex J (informative) Eye diagram . 71
J.1 Eye diagram . 71
J.2 Examples of measured eye diagrams . 72
Bibliography . 73

Figure 1 – Measurement setup and coordinate system (spherical) . 18
Figure 2 – Measurement setup and coordinate system (Cartesian) . 19
Figure 3 – Measurement setup and coordinates for speckle-related optical performance . 20
Figure 4 – Example of I-P and I- P / P characteristics . 22
o o i
Figure 5 – Pulse repetition waveforms of PWM drive with respect to duty cycle . 23
Figure 6 – I and I-P characteristics . 24
th o
Figure 7 – Example of measured colorimetric FFP . 29
Figure 8 – Example of conversion of the measured speckle data on the FFP into data
on a uniform pattern . 31
Figure 9 – Example of conversion of measured normalised illuminance data of colour

speckle on the FFP into data on a uniform pattern . 33

– 4 – IEC 62595-2-4:2020 © IEC 2020
Figure 10 – Example of conversion of measured colour speckle chromaticity data on
the FFP into data on a uniform pattern . 33
Figure 11 – Temperature dependence measurement setup for high-power laser

modules . 36
Figure 12 – Temperature dependence measurement setup for low-power laser modules . 37
Figure 13 – Measurement setup for output pulse waveform . 38
Figure 14 – Example of input/output pulse waveforms . 38
Figure A.1 – Schematic structure of narrow-stripe edge-emitting laser diode. 40
Figure A.2 – Schematic structure of wide-stripe edge-emitting laser diode
...