ISO 22248:2020

INTERNATIONAL ISO
STANDARD 22248
First edition
2020-11
Lasers and laser-related equipment —
Test methods for laser-induced
damage threshold — Classification of
medical beam delivery systems
Lasers et équipements associés aux lasers — Méthodes d'essai du seuil
d'endommagement provoqué par laser — Classification des systèmes
de transmission de faisceau médical
PROOF/ÉPREUVE
Reference number
ISO 22248:2020(E)
©
ISO 2020

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ISO 22248:2020(E)

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© ISO 2020
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Published in Switzerland
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ISO 22248:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
5 Significance and use of the test. 4
6 Apparatus . 4
6.1 General . 4
6.2 Containment box . 6
6.3 Specimen holder . 7
6.4 Lasers and beam delivery systems . 7
6.5 Power meter . 7
6.6 Gas supply system . 7
6.7 Environment . 8
6.7.1 Ambient air conditions . 8
6.7.2 Oxygen enriched atmospheres . 8
6.8 Smoke evacuation device . 8
7 Reagents and materials . 8
8 Preparation of test specimens . 9
9 Preparation of apparatus . 9
10 Test methods .10
10.1 General conditions .10
10.2 Testing during laser irradiation .10
10.3 Testing during laser transmission .11
11 Classification .12
11.1 General .12
11.2 Irradiation ignition testing (I) .13
11.3 Transmission ignition and destruction testing (T/D) .13
11.3.1 Transmission ignition testing (T) .13
11.3.2 Transmission destruction testing (D) .14
12 Test report .16
Bibliography .18
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ISO 22248:2020(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 of 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 www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee
SC 9, Laser and electro-optical systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO 22248:2020(E)

Introduction
Fire in an operating room is the most dangerous situation for patient and staff. Besides electrosurgical
devices and endoscopic light sources, even surgical lasers can be ignition sources for drapes, gowns
and tracheal tubes. This risk was identified very early and several ISO standards for laser proof
materials have been published. The medical beam delivery system itself, however, was out of focus.
Due to the increasing market on the one hand and necessity for cost reduction in health care on the
other hand fibres have come into the market with a risk of self-ignition of the core or cladding material.
Furthermore with reinvention of fibre-applicator-systems for contact application or integrated diffusor
systems they have an increased risk for self-ignition due to high absorption. This document elaborates
reproducible test parameters for medical beam delivery systems.
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INTERNATIONAL STANDARD ISO 22248:2020(E)
Lasers and laser-related equipment — Test methods
for laser-induced damage threshold — Classification of
medical beam delivery systems
1 Scope
This document specifies a method of testing the laser-induced ignition and damage of medical beam
delivery systems to allow checking of suitable products according to the classification system.
NOTE 1 Take care when interpreting these results, since the direct applicability of the results of this test
method to the clinical situation has not been fully established.
NOTE 2 Users of products tested by this method are cautioned that the laser will be wavelength sensitive and
tested at the wavelength for which it is intended to be used. If tested using other wavelengths, the power settings
and modes of beam delivery need to be explicitly stated.
CAUTION — This test method can involve hazardous materials, operations and equipment. This
document provides advice on minimizing some of the risks associated with its use but does not
purport to address all such risks. It is the responsibility of the user of this document to establish
appropriate safety and health practices and to determine the applicability of regulatory
limitations prior to use.
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 13694, Optics and photonics — Lasers and laser-related equipment — Test methods for laser beam
power (energy) density distribution
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/IEC Guide 99 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at
http:// www .electropedia .org/
3.1
afterflame
persistence of flaming of a material, under specified test conditions, after the ignition source has
been removed
[SOURCE: ISO 11810:2015, 3.1]
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ISO 22248:2020(E)

3.2
afterflame time
length of time for which a material continues to flame, under specified test conditions, after the ignition
source has been removed
[SOURCE: ISO 11810:2015, 3.2]
3.3
afterglow
persistence of glowing of a material, under specified test conditions, after cessation of flaming or, if no
flaming occurs, after the ignition source has been removed
[SOURCE: ISO 11810:2015, 3.3]
3.4
afterglow time
time during which a material continues to glow, under specified test conditions, after cessation of
flaming or, if no flaming occurs, after the ignition source has been removed
[SOURCE: ISO 11810:2015, 3.4]
3.5
beam diameter
d
95
diameter of a circular aperture in a plane perpendicular to the beam axis that contains 95 % of the total
beam power (energy)
[SOURCE: ISO 11145:2018, 3.3.1, modified — Value of contained total beam power set to 95 % and
Note 1 to entry removed.]
3.6
beam cross-sectional area
A
95
smallest completely filled area containing 95 % of the total beam power (energy)
[SOURCE: ISO 11145:2018, 3.6.1, modified — Value of contained total beam power set to 95 % and
Note 1 to entry removed.]
3.7
combustion
any continuing burning process that occurs in or on the specimen caused by a chemical process of
oxidation with the liberation of heat
EXAMPLE Flame, smouldering, rapid evolution of smoke.
[SOURCE: ISO 11810:2015, 3.7]
3.8
destruction
damage of the system during laser radiation transmission due to absorption rather than ignition
(crumbling, melting, disconnecting, breaking) with or without loss of parts of the system
3.9
flammable
subject to ignition and flaming combustion
[SOURCE: ISO 11810:2015, 3.9]
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ISO 22248:2020(E)

3.10
ignition
creation of combustion induced by the beam delivery of laser power
[SOURCE: ISO 11810:2015, 3.10]
3.10.1
irradiation ignition
ignition of a specimen by laser irradiation of the specimen from outside
3.10.2
transmission ignition
ignition of a specimen by a laser beam transmission through the specimen
3.11
laser resistance
measure of the ability of a material to withstand laser power without ignition or damage
[SOURCE: ISO 11810:2015, 3.11]
3.12
medical beam delivery system
product intended to transmit the laser beam from the source to the treatment site directly or by the use
of additional applicators
EXAMPLE Articulated arms, hollow waveguides, optical fibres.
Note 1 to entry: Directly means direct application either with bare fibres, shaped fibres or internal marked fibres.
3.12.1
applicator
attachment to the medical beam delivery system at the treatment site
EXAMPLE Focussing handpiece, micromanipulators, scanners, endoscopes, shaped tips like sapphire tips,
ceramic/metal tips, radial tips, focussing lenses or diffusor tips.
3.13
melting behaviour
softening of a material under the influence of heat (including shrinking, dripping and burning of molten
material, etc.)
[SOURCE: ISO 11810:2015, 3.12]
3.14
thermal resistance
ability of a material to resist conduction of heat
[SOURCE: ISO 11810:2015, 3.20]
3.15
product
finished medical device (samples)
3.16
reusable product
product intended to be prepared and re-sterilized for multiple use
[SOURCE: ISO 11810:2015, 3.16]
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3.17
single use
product intended to be used once and then discarded
[SOURCE: ISO 11810:2015, 3.18]
4 Principle
WARNING — This test method can result in a rocket-like fire. Such a fire can produce intense
heat and light and toxic gases.
To simulate worst-case conditions, the material is exposed to laser power of known characteristics in
an environment up to 98 % ± 2 % oxygen.
5 Significance and use of the test
5.1 A medical beam delivery system is intended to transmit the laser beam from the source to the
treatment area. This can be articulated arms, hollow waveguides or optical fibres. It can deliver the
radiation to the target by connected applicators like focussing handpiece, micromanipulators, scanners
or endoscopes or fix mounted applicators as shaped tips like sapphire tips, ceramic/metal tips, radial
tips, focussing lenses or diffusor tips. Another technical solution is the direct application either with bare
fibres, shaped fibres or internal marked fibres.
5.2 This document describes a uniform and repeatable test method for measuring the laser-induced
ignition, flame spread and damage of medical beam delivery systems. Variables involved in laser ignition
have been fixed in order to establish a basis for comparison. This test method can be used to compare
different types and designs.
5.3 A large number and range of variables are involved in ignition. A change in one variable can affect
the outcome of the test. Caution should be observed, since the direct applicability of the results of this
test method to the clinical situation has not been fully established.
NOTE This method can be applied to study the effect of changing the test conditions, but this is outside the
scope of this document. For example, variation of the breathing-gas flow rate or different breathing-gas mixtures
might affect the laser ignition.
5.4 Since an oxygen-enriched atmosphere is often present in the clinical situation, either intentionally
or unintentionally, the test is performed under ambient air conditions and an environment of 60 % ± 2%
and 98 % ± 2 % oxygen, respectively.
5.5 The preparation of the specimen shall be in accordance with the manufacturer's instructions for use.
6 Apparatus
6.1 General
The test apparatus shall consist of a draught-resistant ventilated containment box, specimen holder,
specimen rack, laser energy source and associated parts (see Figures 1 and 2).
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Key
1 medical beam delivery system 6 flashback arrestor
2 medical beam delivery system support using two 7 oxygen flow meter and controller
clamps
3 laser source for irradiation 8 pressure regulator with inlet and outlet gauges
4 containment box (lateral view) 9 quick-action inert gas valve
5 enclosure cover (may be multi-piece) 10 opening for laser access
 11 liquid for cooling/cleaning
Figure 1 — Apparatus for irradiation ignition testing
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ISO 22248:2020(E)

Key
1 medical beam delivery system 6 flashback arrestor
2 medical beam delivery system support using two 7 oxygen flow meter and controller
clamps
3 laser source for transmission 8 pressure regulator with inlet and outlet gauges
4 containment box (lateral view) 9 quick-action inert gas valve
5 enclosure cover (may be multi-piece) 10 opening for laser access
 11 liquid for cooling / cleaning
Figure 2 — Apparatus for transmission ignition testing
6.2 Containment box
The containment box controls the environment around the specimen while allowing the laser beam to
be directed onto the specimen.
The containment box shall
a) be rectangular in shape and have dimensions of approximately 46 cm × 46 cm × 46 cm,
b) be fire-proof and easily cleaned of soot and residue from burned specimens,
c) allow the mounting of the test specimen for the irradiation of the specimen (Figure 1) and
transmitted irradiation (Figure 2),
d) allow access to the specimen,
e) allow direct access of the laser beam to the specimen (Figure 1),
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ISO 22248:2020(E)

f) allow observation with video cameras on the top and on all sides of the box; a minimum of three
video cameras (one camera positioned above the containment box and two cameras positioned at
two of the sides of the containment box) is needed for recording purposes,
g) exhaust the gas and any products of combustion to a safe area,
h) allow cleaning of the box, and cleaning of the covers and/or windows themselves,
i) be capable of maintaining an environment of 60 % ± 2% and 98 % ± 2% respectively oxygen around
the specimen,
j) allow to be rapidly flooded with nitrogen or another gas to extinguish any fire inside the box, and
k) have internal surfaces that are non-reflective to protect the specimen from reflections.
Other configurations may be used, as long as the requirements of the test method as defined herein are
not affected.
6.3 Specimen holder
The specimen holder shall consist of suitable material and construction which allows the passage of the
medical beam delivery system. The specimen shall be positioned within the specimen holder in such a
way that the end of the fibre, specifically the connection between fibre and end piece, is a minimum of
3 cm away from the specimen holder.
6.4 Lasers and beam delivery systems
WARNING — Surgical lasers emit radiation of sufficient power to damage living tissue or ignite
fires directly or by reflection of radiation. In addition to other precautions, test personnel
should be trained in the use of lasers and take proper safety measures based on the type of laser
being used. These precautions should include laser-safety eyewear, protective clothing and
controlled access to the test area.
6.4.1 Various laser types emitting radiation of wavelengths in the ultraviolet, visible and infrared
ranges are used during surgery. Any of these lasers that meets the requirements listed in this test
procedure is suitable for use in this test.
6.4.2 The laser radiation shall be applied with the same optical quality as is typically used for a surgical
procedure. The system shall provide an appropriate beam diameter, d , at the surface of the specimen
95
measured in accordance with ISO 13694.
6.5 Power meter
6.5.1 For measuring the power of the laser radiation, power meters which provide a suitable
measurement range and an uncertainty of less than 5 % shall be used.
6.5.2 The power of radiation transmitted by these systems shall be verified as accurate to ±10 %. This
can be accomplished by use of an external power meter or internal calibration systems.
6.6 Gas supply system
6.6.1 The gas supply system shall provide oxygen to the medical beam delivery system at a controllable
flow rate. Also, the system shall be capable of rapidly flooding the containment box with nitrogen or
other inert gas or stopping oxygen flow, or both, to extinguish any burning material. An oxygen flow
meter and controller and a quick-action inert gas valve shall be part of this system (see Figure 1). The
nitrogen or inert gas supplied shall be at a higher pressure and allow a flow rate of at least an order of
magnitude greater than that of the oxygen supplied to the medical beam delivery system.
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6.6.2 Other arrangements, such as an oxygen flood valve for rapidly purging the containment box or
an inert gas flooding system for rapid extinguishment of burning material, may be used as long as the
requirements of the test method as defined herein are not affected.
6.6.3 Oxygen analyser, any device that can measure the concentration of gaseous oxygen with a
repeatability of at least 1 % of full scale and a calibrated accuracy of at least 1 % of full scale is satisfactory.
The oxygen sensor shall be positioned so as to minimize the chance of its ignition by any fire in the
containment box.
6.6.4 Cooling systems, if the manufacturer does not provide specific requirements for any cooling or
cleaning gases/solutions the test shall be done without such a system because these gases or solutions
can alter the resistance or extinguish nascent fires. If the manufacturer provides specific requirements
the according instructions shall be followed.
6.7 Environment
6.7.1 Ambient air conditions
The tests under ambient air conditions shall be performed at room temperature of 20 °C ± 3 °C and
20 % ± 2 % relative humidity.
6.7.2 Oxygen enriched atmospheres
The tests under oxygen-enriched atmosphere shall be performed at oxygen concentrations of
60 % ± 2 % and 98 % ± 2 %.
The oxygen concentration within the containment box shall be established at the desired ratio by
proportional mixing of nitrogen and oxygen by suitable means.
6.8 Smoke evacuation device
WARNING — Combustion of most materials produces toxic gases such as carbon monoxide,
hydrogen chloride and hydrogen cyanide. Also, the smoke produced in such fires contains
hazardous particles of carbon, silica, unburned matter and other materials.
6.9.1 A device shall be attached to the containment box to safely remove smoke resulting from a
burning specimen but shall be designed to eliminate the chance of drawing fire into the exhaust system.
Placing the containment box in a fume hood that exhausts to a safe location satisfies this requirement.
6.9.2 The smoke evacuation device shall not interfere with maintaining the oxygen environment within
the containment box. For example, the flow of a fume hood shall not create draughts that would enter or
pull gas from the opening for laser access. The smoke evacuation shall not be activated until after the
initiation of combustion.
7 Reagents and materials
7.1 Oxygen, 98 % ± 2 % (volume fraction) pure.
7.2 Nitrogen or other gas (i.e. non-oxidizing, non-flammable), 98 % ± 2 % (volume fraction) pure.
7.3 Absorber materials as phantoms.
7.3.1 Sterile wood mouth spatula, EAN-code 4049500304924 for pre blackening.
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ISO 22248:2020(E)

7.3.2 Agar E406, as carrier substance for:
7.3.2.1 Intralipid, 20% as liquid diffuser.
1)
7.3.2.2 Eosin-methylene blue solution, according to MAY-GRÜNWALD for specific absorption in
visible wavelength range (VIS).
7.3.2.3 ICG indocyanine green, for specific absorption in near infrared wavelength range (NIR).
8 Preparation of test specimens
8.1 Sampling
The test specimen shall be any material, device or system used as medical beam delivery system.
8.1.1 Single use products
Single use products shall be obtained directly from the packaging in which the products are sold.
8.1.2 Reusable products
Reusable products shall be tested new and after reprocessing to the point when their rating changes.
Reprocessing shall include cleaning, decontaminating and, if necessary, sterilization in accordance
with the manufacturer’s recommendations. The point at which the product rating degrades shall be the
maximum allowed number of uses.
8.2 Five test specimens shall be used.
8.3 Materials requiring special treatment or preparation shall be conditioned according to the
manufacturer’s instructions for use. Any special treatment or preparation shall be stated when reporting
results.
8.4 The test specimens shall be free from any extraneous materials, as such materials can significantly
alter the laser ignition.
EXAMPLE Char, ash, soot, blood, mucous, lubricants and other materials, beside the absorber materials
described in 7.3.
8.5 Specimens shall be conditioned for 24 h at 20 °C ± 3 °C and 20 % ± 2 % relative humidity.
9 Preparation of apparatus
9.1 Ensure that the containment box is clean (i.e. free of contaminants) by visual inspection.
NOTE Contamination can interfere with the performance of the test or evaluation of the results.
9.2 Ensure that the laser is in working order, that its operation is understood, and that personal
protection is in place.
9.3 Ensure that there is adequate oxygen for the test and nitrogen or other gas for extinguishing any
resulting fire.
1)  MAY-GRÜNWALD coloration is an example of a suitable product available commercially. This information is
given for the convenience of users of this document and does not constitute an endorsement by ISO of this product.
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