ISO 16331-1:2017
(Main)Optics and optical instruments — Laboratory procedures for testing surveying and construction instruments — Part 1: Performance of handheld laser distance meters
Optics and optical instruments — Laboratory procedures for testing surveying and construction instruments — Part 1: Performance of handheld laser distance meters
ISO 16331-1:2017 specifies procedures for checking compliance with performance specifications of handheld laser distance meters.
Optique et instruments d'optique — Méthodes d'essai de laboratoire des instruments d'observation et construction — Partie 1: Performance de télémètres laser de poche
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INTERNATIONAL ISO
STANDARD 16331-1
Second edition
2017-03
Optics and optical instruments —
Laboratory procedures for testing
surveying and construction
instruments —
Part 1:
Performance of handheld laser
distance meters
Optique et instruments d’optique — Méthodes d’essai de laboratoire
des instruments d’observation et construction —
Partie 1: Performance de télémètres laser de poche
Reference number
ISO 16331-1:2017(E)
©
ISO 2017
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ISO 16331-1:2017(E)
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ISO 16331-1:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 1
5 General information . 2
5.1 General . 2
5.2 Target reflectivity . 2
5.3 Background illumination. 2
5.4 Temperature of key components. 3
5.5 Atmospheric influence . 3
5.6 Measurement resolution . 3
5.7 Average deviation and uncertainty of measurement . 3
5.8 Relevant contribution to uncertainty . 3
5.9 Instruction for instrument specifications . 3
6 Test procedure for determining the compliance with accuracy specifications .4
6.1 Test concept . 4
6.2 Requirements . 4
6.2.1 General. 4
6.2.2 Apparatus . 4
6.3 Configuration of check points . 5
6.4 Measurement procedure . 5
6.4.1 General. 5
6.4.2 Absolute distance test . 5
6.4.3 Background illumination test . 6
6.4.4 Temperature test . 6
6.5 Calculation of deviations and uncertainty of measurement . 7
6.5.1 Absolute distance test . 7
6.5.2 Background illumination test . 7
6.5.3 Temperature test . 8
6.5.4 Combined deviation and combined uncertainty of measurements . . 9
6.5.5 Expanded uncertainty of measurements .10
6.5.6 Statement of test result .10
7 Test procedure for determining compliance with range specifications .10
7.1 Test concept .10
7.2 Requirements .10
7.3 Description of measurement procedure .11
7.4 Calculation of deviation and uncertainty of measurement .11
7.5 Statement of test result .12
Annex A (informative) Example of performance specification .13
Annex B (informative) Examples of determining compliance with accuracy specifications .14
Annex C (informative) Examples of determination of compliance with range specifications .27
Annex D (informative) Background illumination simulation .31
Annex E (informative) Target plates .32
Annex F (informative) Typical characteristics of targets .33
Annex G (informative) Typical alignment issues .35
Bibliography .37
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ISO 16331-1:2017(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by ISO/TC 172, Optics and photonics, Subcommittee SC 6, Geodetic and
surveying instruments.
This second edition cancels and replaces the first edition (ISO 16331-1:2012), which has been technically
revised.
A list of all parts in the ISO 16331 series can be found on the ISO website.
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ISO 16331-1:2017(E)
Introduction
Starting in 1993, several companies developed handheld laser distance meters and introduced them
into the market. With a growing number of different manufacturers, it became obvious that a standard
was needed to establish requirements for device specifications and to describe how to check compliance
with the specified performance of accuracy and range.
ISO 17123 specifies methods of checking specification compliance by the user of the instrument
without any additional measurement equipment. In contrast, ISO 16331 specifies procedures to check
specification compliance using additional laboratory equipment that is unavailable to the typical user.
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INTERNATIONAL STANDARD ISO 16331-1:2017(E)
Optics and optical instruments — Laboratory procedures
for testing surveying and construction instruments —
Part 1:
Performance of handheld laser distance meters
1 Scope
This document specifies procedures for checking compliance with performance specifications of
handheld laser distance meters.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 3534-1, Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in
probability
ISO 9849, Optics and optical instruments — Geodetic and surveying instruments — Vocabulary
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3534-1, ISO 9849,
ISO/IEC Guide 98-3 and ISO/IEC Guide 99 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp/
4 Symbols and abbreviated terms
Table 1 — Symbols
D distance
mean value of a set of distances
D
Δ deviation
k coverage factor for a level of confidence of 95 %
M measurement value
N number of measurements taken at each check point
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ISO 16331-1:2017(E)
Table 1 (continued)
R resolution
s experimental standard deviation
u standard uncertainty of measurement
U expanded uncertainty
Table 2 — Subscripts and abbreviated terms
AD absolute distance
Add additional contribution
BG background illumination
CP X check point X
REF reference
M measurement
max maximum
min minimum
high high
low low
C combined
CP checkpoint
i index for individual cases
RM measurement resolution
RT range test
X index for individual cases
T temperature
T05 temperature 5 °C
T40 temperature 40 °C
5 General information
5.1 General
The maximum measurement range on typical targets (info and examples, see Annex F) and the
uncertainty of measurements provided by handheld laser distance meters are influenced by the
following factors.
5.2 Target reflectivity
The higher the target reflectivity, the better the signal to noise ratio at the receiver; therefore better
measurement performance is achievable. For more details, refer to Annex F.
As handheld laser distance meters are used on construction sites and for indoor applications, typical
targets are painted walls, bricks, concrete, wood, and similar targets. Special attention has to be paid to
the effect of penetration of the laser into certain materials, e.g. white marble.
5.3 Background illumination
Background light in indoor applications is typically below 3 klx and therefore negligible. However, in
outdoor applications, the sunlight reflected by the target might reach an illuminance of up to 100 klx
and might cause a degradation of the signal to noise ratio and therefore, a poorer performance of the
instrument.
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ISO 16331-1:2017(E)
5.4 Temperature of key components
The temperature of the laser system and of the receiver system has an influence on the uncertainty of
distance measurement. Most of these instruments have a built-in temperature compensation system to
minimize this kind of influence.
5.5 Atmospheric influence
The maximum range and the accuracy of laser distance meters are influenced by meteorological
conditions at the moment of the measurements being taken. These conditions include variations in
air temperature, air pressure and humidity of the air. Distances calculated by handheld laser distance
meters are based on predefined meteorological conditions. To achieve accurate measurements,
in particular at long distances, these meteorological variables in the distance calculation shall be
determined and the measured distance shall be corrected accordingly if the device under test offers
this possibility.
5.6 Measurement resolution
The measurement resolution of a measurement instrument shall be at least two times better than the
specified accuracy. For very accurate measurements, like in a calibration situation, a laser distance
meter shall offer a unit setting which allows a measurement resolution that is at least five times better
than the specified accuracy.
5.7 Average deviation and uncertainty of measurement
The typical user of handheld laser distance meters wants to take only one single measurement and
wants to rely on the specified maximum tolerances. Therefore, it is the value of the combined and
expanded uncertainty of a single measurement that the user wants to see below the tolerance limits.
5.8 Relevant contribution to uncertainty
Table 3 — Relevant contribution to uncertainty
a
Uncertainty contribution Distribution Type
b
Reference system Normal B
Measurement resolution Rectangular B
Absolute distance test Normal A
(internal noise at typical conditions)
Background illumination (additional offset and noise) Normal A
Temperature (additional offset and noise) Normal A
a
For further information, refer to GUM “Guide to the Expression of Uncertainty in
Measurement”.
b
The uncertainty contribution of the “reference system” comprises a number of
uncertainty contributions, including inter alia, contributions by the uncertainty of the length
standard used, by the uncertainty due to an imperfect geometric alignment of reference and
device under test or by the uncertainty due to imperfect temporal synchronization. All these
contributions have to be carefully, individually assessed to quantify the overall uncertainty of
the reference system.
5.9 Instruction for instrument specifications
As customers of handheld laser distance meters usually are not used to the term “uncertainty of
measurement”, the manufacturers may use the expression “measurement accuracy” in their product
specification.
Since the performance of a handheld laser distance meter depends on various conditions, the
specification of the product shall indicate the conditions that apply, e.g. distance dependency,
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ISO 16331-1:2017(E)
target reflectivity, background illumination and temperature range. It is mandatory to indicate the
performance data (accuracy and range) with favourable conditions and with unfavourable conditions.
Favourable conditions are white and diffuse reflecting target, low background illumination and
temperatures about 20 °C.
Unfavourable conditions are targets with lower or higher reflectivity, high background illumination
and temperatures at the upper or lower end of the specified temperature range.
For an example, see Annex A.
6 Test procedure for determining the compliance with accuracy specifications
6.1 Test concept
As mentioned before, the accuracy of handheld laser distance meters depends on various factors.
The test concept of this document focuses on the main influences, such as measurement distance,
temperature of instrument and background illumination.
The target reflectivity, which also can have an impact on the accuracy, is not tested directly by changing
targets with different reflectivity factors. The reason is that it is quite difficult to get targets with well
defined, homogeneous and stable reflectivity factors. In addition, the effect of a target with a lower
reflectivity factor of 25 % can be tested using a target with 100 % reflectivity at double distance.
Therefore, the effects of lower reflectivity factors are indirectly tested at the absolute distance test
described in 6.4.2.
6.2 Requirements
6.2.1 General
To determine compliance with the accuracy specifications for handheld laser distance meters, the
following measurement setup is used.
For examples of determining compliance with accuracy specifications, see Annex B.
6.2.2 Apparatus
6.2.2.1 Target plate, meeting the following specifications:
Size: 0,25 m × 0,25 m;
Reflectivity: (95 ± 5) % (see Annex E).
Special attention is to be paid to the effect of penetration of the laser beam into certain materials (see
Annex F). In addition, specular surfaces and reflectors should be avoided along the measurement line.
6.2.2.2 Background illumination lamp, that shall achieve at least an illuminance of 30 klx on the
used target plate. Check with an illuminance meter (lux meter) directed as perpendicularly as possible to
the target at 0,1 m distance from the target.
6.2.2.3 Temperature chamber, capable of heating the devices under test up to +40 °C and cooling
them down to +5 °C. The measurements can be taken inside a big temperature chamber or by taking the
heated (or cooled) devices out of the chamber and immediately taking the measurements on a known
reference distance.
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ISO 16331-1:2017(E)
6.2.2.4 Calibrated reference distance measurement system, to determine the distance between
target and device under test. The uncertainty of measurement of the reference system shall be 20 % or
less than the expected uncertainty of measurement of the device under test.
6.3 Configuration of check points
Select 10 check points CP01 to CP10.
Check point CP10 shall be set either to the longest specified distance of the device under test or to
the maximum range of the reference distance measurement system, but at least 10 m. The following
configuration of check points takes into consideration that typical customers measure shorter distances
more frequently than longer ones.
D(CP01) = 0,02 · D(CP10)
D(CP02) = 0,03 · D(CP10)
D(CP03) = 0,05 · D(CP10)
D(CP04) = 0,07 · D(CP10)
D(CP05) = 0,10 · D(CP10)
D(CP06) = 0,20 · D(CP10)
D(CP07) = 0,30 · D(CP10)
D(CP08) = 0,50 · D(CP10)
D(CP09) = 0,70 · D(CP10)
D(CP10) = max distance
X: Distance (m)
Figure 1 — Example: CP10 = 20 m
6.4 Measurement procedure
6.4.1 General
To determine compliance with accuracy specifications for handheld laser distance meters, the following
procedure is recommended.
6.4.2 Absolute distance test
This test shall be performed under favourable conditions.
Target reflectivity: (95 ± 5) %;
Background illumination: <3 klx;
Temperature range: (20 ± 5) °C;
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ISO 16331-1:2017(E)
Define the check points (see 6.3).
At each check point, determine the reference distance with the reference distance measurement system
and take 10 measurements with the device under test. Ensure correct alignment of the handheld laser
distance meter to the target by checking at the shortest and the longest distance of the reference system
that the laser spot still hits the target at the centre mark and that the target is oriented perpendicularly
to the laser beam within ±1°. Due to this alignment procedure, an additional offset error might come
into account which is not allowed to be compensated by a corrective value (for more details, refer to
Annex G).
6.4.3 Background illumination test
This test evaluates the influence of high background illumination on the measurement result in
comparison to the result of measurements at low background illumination.
Target reflectivity: (95 ± 5) %;
Background illumination, case A: <3 klx;
Background illumination, case B: >30 klx;
Temperature range: (20 ± 5) °C.
Build up the measurement setup for the background illumination test (see Annex D for an example of a
possible setup). At the checkpoint CP01, CP02 or CP03 (depending on which point fits better for the test
under 6.4.4), set the background illumination reflected by the measurement target to an illuminance
less than 3 klx. Determine the reference distance with the reference distance measurement system
and take and record 10 measurements with the device under test. In the next step, set the background
illumination reflected by the measurement target to an illuminance higher than 30 klx and take and
record another 10 measurements with the device under test.
6.4.4 Temperature test
This test evaluates the influence of other ambient temperatures on the measurement result in
comparison to the measurement results at 20 °C.
Target reflectivity: (95 ± 5) %;
Background illumination: <3 klx;
Temperature, case A: +5 °C ± 2 °C;
Temperature, case B: +20 °C ± 2 °C;
Temperature, case C: +40 °C ± 2 °C.
Put the device under test into a temperature chamber and let the instruments adapt to the test
temperature of case A (recommendation: 2 min/°C). Then, take the instrument out of the chamber and
immediately take and record 10 measurements at the distance CP01, CP02 or CP03 (same distance as
6.4.3). Check that the background illumination reflected by the target is below 3 klx. Repeat the same
procedure for the remaining two test cases. At test case A, verify that the receiver optics do not mist up
during measurements.
Alternatively, the measurements could be taken directly inside a temperature chamber if the instrument
is mounted on a reference distance measuring bar. In this case, the expansion of the reference distance
measuring bar over temperature has to be compensated in the calculations.
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ISO 16331-1:2017(E)
6.5 Calculation of deviations and uncertainty of measurement
6.5.1 Absolute distance test
Calculate the deviation ΔM of all measurements M from the corresponding reference value at each
i i
check point.
ΔM = M − D (1)
i i REF
Check, if all calculated deviations ΔM are inside the specified tolerance field defined for favourable
i
conditions. Assuming a level of confidence of 95 %, only 5 of the 100 measured points (10 at each check
point) are allowed to lie outside the tolerance field with favourable conditions.
At each check point, calculate the experimental mean value of the absolute distance test, D :
AD
1
N
D =∑ M (2)
AD i=1 i
N
Calculate at each check point the deviation ΔD of the experimental mean value from the
AD
corresponding reference value:
Δ=DDD− (3)
AD AD REF
At each check point, calculate the corresponding experimental standard deviation, s , of the measured
AD
values and take it as the standard uncertainty, u , associated with the measured values:
AD
2
1 N
us==�� MD− (4)
()
∑
AD AD i AD
i=1
N −1
6.5.2 Background illumination test
Calculate for both cases, low background illumination BG, low < 3 klx, and high background illumination
BG, high > 30 klx, and for each measurement M , the deviation ΔM from the reference value.
i,X i,X
For each background illumination case, calculate the experimental mean value, D :
BG,X
1
N
D =∑ M (5)
BG,Xii=1,X
N
where X = background low, high.
Calculate the deviation ΔD of the experimental mean value from the corresponding reference value:
BG,X
Δ=DD −D (6)
BG,XXBG, BG,REF
where X = background low, high.
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ISO 16331-1:2017(E)
Calculate the additional deviation DD caused by the background illumination:
BG,Add
DDD=− D (7)
BG,Add BG,high BG,low
Calculate the corresponding experimental standard deviations for both cases of background
illumination and take them as the standard uncertainties associated with both cases:
1 N
2
uS== ()MD− (8)
BG,X
BG,X BG,X ∑ ix,
i=1
N−1
where X = background low, high.
Calculate the additional uncertainty, u , caused by the background illumination, assuming that
BG,Add
u > u . If u < u , then u = 0:
BG,high BG,low BG,high BG,low BG,Add
22
uu=−u (9)
BG,Add BG,high BG,low
6.5.3 Temperature test
Calculate for each temperature case and for each measurement M , the deviation ΔM from the
i,X i,X
corresponding reference value.
For each temperature case, calculate the corresponding experimental mean value, D :
T,X
1
N
D =∑ M (10)
T,Xii=1 ,X
N
where X = +5 °C, +20 °C, +40 °C.
Calculate the deviation D of the experimental mean value from the corresponding reference value:
T,X
Δ=DD −D (11)
T,XXT, T,REF
where X = +5 °C, +20 °C, +40 °C.
Calculate the additional deviation ΔD and ΔD caused by the temperature influences at
T05,Add T40,Add
+5 °C and +40 °C in reference to the value calculated at 20 °C:
Δ=DDΔ−ΔD (12)
T05,AddT,5°°CCT,20
Δ=DDΔ−ΔD (13)
T40,AddT,40T°°CC,20
Calculate the corresp
...
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