ISO/TR 14880-5:2010

Optics and photonics — Microlens arrays — Part 5: Guidance on testing

ISO/TR 14880-5:2010 gives guidelines for the testing of microlenses. It applies to microlenses in arrays where very small lenses are formed inside or on one or more surfaces of a common substrate. ISO/TR 14880-5:2010 addresses the measurement of optical and geometrical properties of single microlenses as well as microlens arrays. When testing a microlens or microlens array, the test method is selected according to the parameters to be measured, the size and structure of the microlens and its application. ISO/TR 14880-5:2010 guides the user to select the appropriate measurement method from the available ISO standards.

Optique et photonique — Réseaux de microlentilles — Partie 5: Lignes directrices pour essai

General Information

• Status: Published
• Publication Date: 05-Dec-2010
• ICS: 31.260 - Optoelectronics. Laser equipment
• Technical Committee: ISO/TC 172/SC 9 - Laser and electro-optical systems
• Drafting Committee: ISO/TC 172/SC 9/WG 7 - Electro-optical systems other than lasers
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 22-Jun-2015

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 14880-5
First edition
2010-12-15

Optics and photonics — Microlens
arrays —
Part 5:
Guidance on testing
Optique et photonique — Réseaux de microlentilles —
Partie 5: Lignes directrices pour essai




Reference number
ISO/TR 14880-5:2010(E)
©
ISO 2010

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ISO/TR 14880-5:2010(E)
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ii © ISO 2010 – All rights reserved

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ISO/TR 14880-5:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Symbols and units.1
5 Coordinate system .2
6 Test conditions .3
7 Test guide.4
7.1 General .4
7.2 Guide to test with measurement equipment .4
7.3 Measurements possible with specific equipment.6
7.4 Measurement equipment for testing properties of a microlens .8
7.4.1 Test method flow chart .8
7.4.2 Test methods for optical properties of a single microlens.9
7.4.3 Test methods for geometrical properties of single microlenses .10
7.4.4 Test methods for optical properties of microlens arrays.10
7.4.5 Test methods for geometrical properties of microlens arrays.11
8 Test report.11
Annex A (informative) Measurement guide for microlens property test.12
Annex B (informative) Discussion of Annexes to ISO 14880-2, ISO 14880-3 and ISO 14880-4.14
Bibliography.17

© ISO 2010 – All rights reserved iii

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ISO/TR 14880-5:2010(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TR 14880-5 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee
SC 9, Electro-optical systems.
ISO 14880 consists of the following parts, under the general title Optics and photonics — Microlens arrays:
⎯ Part 1: Vocabulary
⎯ Part 2: Test methods for wavefront aberrations
⎯ Part 3: Test methods for optical properties other than wavefront aberrations
⎯ Part 4: Test methods for geometrical properties
⎯ Part 5: Guidance on testing [Technical Report]
iv © ISO 2010 – All rights reserved

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ISO/TR 14880-5:2010(E)
Introduction
This part of ISO 14880 is intended as a guide to the selection and use of the appropriate method for testing
optical and geometrical properties of a single microlens or microlens arrays. Examples of applications for
microlens arrays include three-dimensional displays, coupling optics associated with arrayed light sources and
photo-detectors, enhanced optics for liquid crystal displays, and optical parallel processor elements.
The testing of microlenses is in principle no different to testing any other lens. The same parameters need to
be measured and the same techniques used. However, in many cases the measurement of very small lenses
presents practical problems which make it difficult to use the standard equipment that is available for testing
normal-size lenses.
The growing market in microlens arrays has generated a need for agreement on basic terminology and test
methods. Standard terminology and clear definitions are needed not only to promote applications but also to
encourage scientists and engineers to exchange ideas and new concepts based on common understanding.
The purpose of ISO 14880 is to improve the compatibility and interchange ability of lens arrays from different
suppliers and to enhance development of the technology that uses microlens arrays. The various parts of
ISO 14880 define terms and describe methods for testing wavefront aberrations, optical properties other than
wavefront aberrations, and test methods for geometrical properties. This part of ISO 14880 contributes to the
purpose by guiding the user to select the appropriate part of ISO 14880 for testing microlens properties,
however the user is not limited to these techniques.

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TECHNICAL REPORT ISO/TR 14880-5:2010(E)

Optics and photonics — Microlens arrays —
Part 5:
Guidance on testing
1 Scope
This part of ISO 14880 gives guidelines for the testing of microlenses. It applies to microlenses in arrays
where very small lenses are formed inside or on one or more surfaces of a common substrate.
This part of ISO 14880 addresses the measurement of optical and geometrical properties of single
microlenses as well as microlens arrays.
When testing a microlens or microlens array, the test method is selected according to the parameters to be
measured, the size and structure of the microlens and its application. This part of ISO 14880 guides the user
to select the appropriate measurement method from the available ISO standards.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 14880-1, Optics and photonics — Microlens arrays — Part 1: Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14880-1 apply.
4 Symbols and units
Symbols and units of measurement that are used in this part of ISO 14880 are given in Table 1.
© ISO 2010 – All rights reserved 1

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ISO/TR 14880-5:2010(E)
Table 1 — Symbols and units of measurement
Symbol Unit Term
2
1 A mm diffraction-limited optical aperture
d
2
2 A mm geometric aperture
g
3 a , a mm lens radius
1 2
4 2a , 2a mm lens width
1 2
−2
5 D mm lens density
n
6 h mm surface modulation depth
7 L , L mm edge length of substrate
1 2
8 NA none numerical aperture
9 NA none diffraction limited numerical aperture
d
10 NA none geometrical numerical aperture
g
11 n (x, y, z) none refractive index
12 n none refractive index (lens centre)
0
13 P , P mm pitch
x y
14 f mm effective back focal length
E,b
15 f mm effective front focal length
E,f
16 R mm radius of curvature
c
17 S , S , S mm coordinates of focal spot position
x y z
18 ΔS , ΔS , ΔS mm focal spot position shift
x y z
19 T mm thickness of substrate
20 T mm physical thickness
c
21 W , W mm focal spot size
x y
22 x, y, z mm coordinate of lens aperture centre position
23 θ degree acceptance angle
24 Φ parts of the wavelength, λ wavefront aberration
rms
25 λ μm wavelength
26 v none effective Abbe-number
eff

5 Coordinate system
A Cartesian coordinate system as shown in Figure 1 can be used to describe the radiation propagation in a
microlens array. Most parameters to be measured relate to individual microlenses.
The fundamental structure of a microlens array is illustrated in Figure 2.
2 © ISO 2010 – All rights reserved

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ISO/TR 14880-5:2010(E)

Key
1 Substrate
2 Microlens
Figure 1 — Microlens array with a Cartesian coordinate system


Figure 2 — Fundamental structure of microlens array
6 Test conditions
Care should be taken to ensure the test samples and equipment are handled under the conditions described
in the appropriate standard, e.g. ISO 14880-2.
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ISO/TR 14880-5:2010(E)
7 Test guide
7.1 General
It is usually necessary to ensure optical surfaces are clean before measurement.
7.2 Guide to test with measurement equipment
Table 2 shows several measurement methods and types of equipment which can be used to measure
parameters.
For example, a lens radius (a , a ) can be measured with a stylus instrument, a confocal measurement
1 2
system or a microscope with linear scale.
Table 2 — Test equipment and reference standard for parameters to be measured
Symbol Unit Term (parameter to be Equipment Reference
measured) standards
2
1 A diffraction-limited optical microscope with linear scale —
mm
d
aperture
interferometer with aperture stop —
and linear scale
2
2 A geometrical aperture micrometer —
mm
g
microscope with linear scale —
3 a , a mm lens radius stylus instrument ISO 14880-4
1 2
confocal measurement systems ISO 14880-4
microscope with linear scale —
4 2a , 2a mm lens width stylus instrument ISO 14880-4
1 2
confocal measurement systems ISO 14880-4
microscope with linear scale —
−2
D
5 lens density stylus instrument ISO 14880-4
mm
n
confocal measurement systems ISO 14880-4
microscope with linear scale —
6 h mm surface modulation depth stylus instrument ISO 14880-4
confocal measurement systems ISO 14880-4
7 L , L mm edge lengths of substrate microscope with linear scales —
1 2
NA
8 none numerical aperture calculated from aperture and —
focal length values
measured directly from the —
divergence introduced by the
microlens when illuminated by a
collimated beam
9 NA none diffraction-limited calculated from diffraction-limited —
d
numerical aperture aperture and focal length values
10 NA none geometrical numerical calculated from geometrical —
g
aperture aperture and focal length values


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ISO/TR 14880-5:2010(E)
Table 2 (continued)
Symbol Unit Term (parameter to be Equipment Reference
measured) standards
11 n (x, y, z) none refractive index refractometer, for example Abbe —
or Pulfrich type or interferometer
such as Mach-Zehnder or
shearing type
n
12 none refractive index (lens refractometer, for example Abbe —
0
centre) or Pulfrich type or interferometer
such as Mach-Zehnder or
shearing type
13 P , P stylus instrument ISO 14880-4
mm pitch
x y
microscope with linear scale —
14 f mm effective back focal length collimated source and ISO 14880-3
E,b
microscope
wavefront measuring systems ISO 14880-3
with linear scale
confocal measurement systems ISO 14880-3
f
15 mm effective front focal length collimated source and ISO 14880-3
E,f
microscope
wavefront measuring systems ISO 14880-3
with linear scale
confocal measurement systems ISO 14880-3
16 R collimated source and ISO 14880-4
mm radius of curvature
c
microscope
interferometer with linear scale ISO 14880-4
17 S , S , S mm coordinates of focal spot microscope with linear scale —
x y z
position
18 mm focal spot position shift microscope with linear scale —
ΔS , ΔS , ΔS
x y z
19 T mm thickness of substrate micrometer —
20 T mm physical thickness micrometer ISO 14880-4
c
21 W , W mm focal spot size image sensor camera —
x y
22 x, y, z mm coordinates of lens microscope with linear scale —
aperture centre position
23 θ degree acceptance angle gonio photometer —
Φ
24 parts of the wavefront aberration interferometer ISO 14880-2
rms
wavelength, ISO 10110-14
λ
Shack-Hartmann sensor ISO 14880-2
25 λ μm wavelength spectrometer —
26 v none effective Abbe-number effective Abbe-number is given ISO 14880-3
eff
by:
1

f()λ
2
v =
eff
11
−
ff()λ (λ)
13
27 CE none coupling efficiency calculated from Strehl ratio ISO 14880-3

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ISO/TR 14880-5:2010(E)
Table 2 (continued)
Symbol Unit Term (parameter to be Equipment Reference
measured) standards
28 IQ none imaging quality test chart projection —
calculated wavefront analysis ISO 14880-2
MTF analysis ISO 15529
29 uniformity none uniformity of array pair of similar lens arrays to ISO 14880-4
generate moiré patterns
Also, measurements on single
lenses sampled from array may
give a good indication.

7.3 Measurements possible with specific equipment
Table 3 shows measurement methods and equipments which can be used to measure single microlens and/or
microlens array properties. Several properties may be measured with each piece of equipment.
Table 3 — Measurements possible with specific equipment
Equipment SA O G Symbol Unit Term Reference
standards
A collimated source and # # 14 f mm effective back focal ISO 14880-3
E,b
microscope length
# # 15 f mm effective front focal ISO 14880-3
E,f
length
#  # 16 R mm radius of curvature ISO 14880-4
c
B effective Abbe-number is # # 26 v none effective Abbe-number ISO 14880-3
eff
given by: (chromatic aberration)
1

f()λ
2
v =
eff
11
−
ff()λ (λ)
13
calculated from appropriate # # 8 NA none numerical aperture —
aperture and focal length
# # 9 NA none diffraction-limited —
d
values
numerical aperture
# # 10 NA none geometrical numerical —
g
aperture
calculated from Strehl # # 27 CE none coupling efficiency ISO 14880-3
ration
calculated wavefront # # 28 IQ none imaging quality ISO 14880-2
analysis
C confocal measurement # # 14 f mm effective back focal ISO 14880-3
E,b
systems length
# # 15 f mm effective front focal ISO 14880-3
E,f
length
# # # 3 a , a mm lens radius ISO 14880-4
1 2
# # # 4 2a , 2a mm lens width ISO 14880-4
1 2
−2
# # 5 D mm lens density ISO 14880-4
n
# # 6 h mm surface modulation ISO 14880-4
depth
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ISO/TR 14880-5:2010(E)
Table 3 (continued)
Equipment S A O G Symbol Unit Term Reference
standards
D pair of similar lens arrays # # 29 uniformity none uniformity of array ISO 14880-4
to generate moiré patterns
E gonio photometer # # 23 θ degree acceptance angle —
F image sensor camera # # 21 W , W mm focal spot size —
x y
G refractometer, for example # # 11 n (x, y, z) none refractive index —
Abbe or Pulfrich type
# # 12 n none refractive index (lens —
0
centre)
H interferometer # # 24 Φ parts of the wavefront aberration ISO 14880-2
rms
wavelength, ISO 10110-
λ 14
interferometer with linear #  # 16 R mm radius of curvature ISO 14880-4
c
scale
2
interferometer with # # 1 A mm Diffraction-limited —

d
aperture stop and linear optical aperture
scale
interferometer such as # # 11 n (x, y, z) none refractive index —
Mach-Zehnder or shearing
# # 12 n none refractive index (lens —
0
type
centre)
I micrometer # # 20 T mm physical thickness ISO 14880-4
c
# # 19 T mm thickness of substrate —
2
  2 A mm geometrical aperture —
g
2
J microscope with linear #  # 1 A mm diffraction-limited optical —
d
scale aperture
2
#  # 2 A mm geometrical aperture —
g
#  # 3 a , a mm lens radius —
1 2
#  # 4 2a , 2a mm lens width —
1 2
−2
# # 5 D mm lens density —
n
# # 7 L , L mm edge lengths of —
1 2
substrate
# # 13 P , P mm pitch —
x y
# # 17 S , S , S mm coordinates of focal —
x y z
spot position
# # 18 ΔS , ΔS , mm focal spot position shift —
x y
ΔS
z
# # 22 x, y, z mm coordinates of lens —
aperture centre position
K MTF analysis # # 28 IQ none imaging quality ISO 15529
L Shack-Hartmann sensor # # 24 Φ parts of the wavefront aberration ISO 14880-2
rms
wavelength,
λ
M stylus instrument #  # 3 a , a mm lens radius ISO 14880-4
1 2
#  # 4 2a , 2a mm lens width ISO 14880-4
1 2
-2
# # 5 D mm lens density ISO 14880-4
n
# # 6 h mm surface modulation ISO 14880-4
depth
# # 13 P , P mm pitch ISO 14880-4
x y
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ISO/TR 14880-5:2010(E)
Table 3 (continued)
Equipment SA O G Symbol Unit Term Reference
standards
N test chart projection # # 28 IQ none imaging quality —
O wavefront measuring # # 14 f mm effective back focal ISO 14880-3
E,b
systems with linear scale length
# # 15 f mm effective front focal ISO 14880-3
E,f
length
P spectrometer   25 λ μm wavelength —
(S: single microlens test; A: microlens array test; O: optical property; G geometrical property)

7.4 Measurement equipment for testing properties of a microlens
7.4.1 Test method flow chart
The flowc
...