Working with lasers

Introduction

A laser is a device that sends out a small, parallel and coherent bundle of (electromagnetic) radiation of a specific wavelength. Because of these properties, the radiation intensity in the beam can still be high at a great distance. If living tissue is exposed to this radiation for too long, the heat development from the absorption of the radiation can cause damage to the tissue. A too high radiation intensity of the eye can inflict damage to the cornea, lens or iris. The maximum amount of acceptable radiation intensity for the skin is several orders of magnitude higher than for the eye. The required safety measures as regards the radiation risk are therefore primarily focused on the dangers for the eye.

If a staff member is or staff members are working with lasers, then the guidelines described in the 'Working with lasers' document are required to be adhered to.

Legislation

Lasers which may emit harmful radiation must be made of proper material, be properly constructed and be in good condition. Depending on the danger of the work equipment they are to be placed in a room in such a way and/or be fitted out, installed or protected in such a way that when in operation no harmful radiation can be released.

If the release of harmful radiation cannot be prevented, such organisational measures are to be taken that the harmful effects are kept to a minimum. If this is still insufficient, adequate personal protection gear is to be made available.

Hazard identification and risk assessment (RI&E)

The risks of working with lasers are to be identified and assessed in advance via a more detailed investigation.

Implementation at the UT

Conducting the RI&E

Prior to commencing activities involving lasers, a hazard identification and risk assessment of these activities needs to have been performed. The identification of hazards should focus on risks of laser radiation, such as possible damage to the eyes and skin, the possible release of ozone, fire hazards, x-rays, and the like. . The following aspects should be considered.

I Information about the laser system:

·

Risk category of the laser:
Lasers are classified into four risk categories on the basis of energy and duration of the pulse (pulse lasers) or the power of the beam(continuous-wave laser). Category 1 lasers are considered unharmful and category 4 lasers are considered the most dangerous. The classification of lasers can be found in attachment 1. The risk category in which each laser or laser system belongs is required to be determined, starting with category 1M and above. In case of doubt, consult the laser expert. The laser expert keeps an index (see attachment 2 for format) in which the laser equipment (starting with category 1M) has been listed, including all relevant technical details.

·

Information about the work
Which work activities involve the use of lasers (continuous, periodical).

·

Information about possible risks
The possible harmful effects that may occur due to contact with the laser beam (risks for skin and eye).
Other possible dangers in the use of lasers include:

- accidents as a result of high electric voltage in the power supply equipment;

- the possible creation of fumes, aerosols or ozone;

- noise in case of pulsed high-energy lasers;

- explosions and implosions of gas lasers’ glass tubes used;

- high-intensity visible light caused by welding operations;

- Fire

- burning of skin/clothing by visible or invisible lasers;

- accumulation of static electricity.

·

Other information
Type of laser (excimer, argon, YAG etc.)

II Type of work

·

For what purpose is the laser used?

·

How can staff members come into contact with the laser beam?

III Staff members exposed to risk(s)

·

Which staff members may come into contact with the laser beam? Don't forget to also include staff members who may indirectly be exposed to these hazards (students, technicians). What kind of education do these staff members have?

IV Action Plan

·

Indicate what measures are to be taken to prevent contact with the laser beam. Attention should be given to the following issues:

-

Using a method with the least possible current intensity/light intensity.
It is obligatory to use another method, if possible, that generates less UV radiation. If the current intensity increases, the UV radiation does, too. It is compulsory to use a method that uses the lowest possible current intensity.

-

Shielding the laser beam as much as possible.
The laser beam is to be shielded as much as possible. In addition, possible exposure can be reduced for example by a beam catcher at the end of the laser, by not applying reflecting surfaces in the laser trajectory, and by securing the shielding of the laser beam.

-

Working in specially marked spaces.
The room specially used for this may only be accessed by authorized personnel who have received instructions. They need to have a proof of admission, for example authorization of UT pass or special key to access the room. The room and equipment are required to have been equipped with the warning signs and symbols belonging to the risk category. The entrance doors are required to have a clear sign (‘laser active') and/or to have a facility that prevents the doors from being opened while the laser is active.

-

Not using materials that may catch fire when the laser beam is directed towards them.

-

Wearing personal protective gear including laser goggles and protective clothing (if prescribed by the RI&E) is compulsory.

-

Implementing emergency stop facilities, both inside and outside the room..

-

When using a laser of the categories 3R, 3B and 4 you are required to consult a laser expert.

-

The laser expert is authorized to stop the activities if category 3R, 3B or 4 lasers are being used without proper instruction.

The measures to be taken depend on the risk category of the laser. The table below shows the compulsory measures per control level.

Control measures

Risk categories

1

1M

2

2M

3R

3B

4

1

Labelling laser equipment

Yes

Yes

Yes

Yes

Yes

Yes

Yes

2

Installing beam catcher at end of beam

No

Yes

Yes

Yes

Yes

Yes

Yes

3

Laser users have been instructed (verbally and in writing)

No

Yes

Yes

Yes

Yes

Yes

Yes

4

Only authorized staff members have access

No

No

No

No

Yes

Yes

Yes

5

The workplace has to be separated from any other activities in the same building

No

No

No

No

Yes, screening off from other spaces is possible

Yes

Yes

6

To be installed outside the room:

- laser beam symbol

- red warning lamp switched on when laser is in operation

- text with further instructions (e.g. ‘authorized personnel only’).

No

No

No

No

No

Yes

Yes

7

Wearing laser goggles

No

No

Yes

if looking directly into beam

Yes

if looking directly into beam

Yes,

if looking directly into beam

Yes, always

Yes, always

8

Securing machine with key-operated switch

No

No

No

No

Yes

Yes

Yes

9

When using optical observation instruments exposure, both hazardous and non-hazardous, should be prevented.

No

Yes

Yes

Yes

Yes

Yes

Yes

10

Keep trajectory below eye level

No

Yes

Yes

Yes

Yes

Yes

Yes

11

Beam to be screened off or made unreachable as much as possible. Security measures applied to the shielding have to be reliable.

No

No

No

No

Yes

Yes

Yes

12

Reflective surfaces may be present in the trajectory of the beam.

Yes

Yes

Yes

Yes

No

No

No

13

Appointment laser expert

No

No

No

No

Yes

Yes

Yes

14

Create a log with the following:
- registration type of laser
- laser user or users
- use of the laser

See attachment 2

No

No

No

No

Yes

Yes

Yes

Please note:

A laser of a certain category may be transformed into a category 1 laser system by applying a protective casing around the object to be worked on. The conditions of the protective casing are:

-

nobody can be hit directly by the beam.

-

the mirror reflected beam and the diffuse reflected beam are incapable of causing any eye damage.

-

if the protective casing is removed (partly or entirely) it is not possible for the laser to become active.

Technical and organizational measures

Emergency assistance (BHV)

It is required to first check whether a special calamity procedure needs to be put in place together with the building’s emergency assistance (BHV) team. The BHV staff are to know in what way they can safely access the space where the lasers are kept (be aware of where the central emergency switch is, and such). This has to be included in the information provided to any staff members and BHV staff involved.

Information

Staff working with a laser have to be specifically instructed in the dangers and risks involved (both verbally and in writing). In addition a (written) fixed procedure for working with lasers has to be present at the laser equipment, in both Dutch and English for non-Dutch speaking staff.

Periodical Occupational Health Examination (PAGO) / Preventive Medical Examination (PMO)

The value of eye examinations on commencement of activities and periodically afterwards is disputed. However, an individual staff member who would like to have an eye examination regardless, should be given the opportunity to do so. After an accident involving a laser in the context of which there is a suspicion of eye damage, it is desirable for an eye examination to be performed by an ophthalmologist within 72 hours, and for any damage to be recorded as accurately as possible.

Literature/further information

1.

Guidelines laser safety for research and education I.A.V.M. report no. 12 (September 1985)

2.

Laser safety in health care (September 2006)

3.

Laser safety in health care, risk profile (September 2011)

4.

Safety and health aspects of working with high-intensity lasers (January 1988)

5.

NEN –EN-60825-1, 2007 Safety laser products, equipment classification and requirements.

6.

AI 60 Artificial optic radiation, first printing, 2011

7.

SZW Optic radiation in labour situations, 2006

ATTACHMENT 1 - Classification of laser categories

Category classification

Regarding the dangers, lasers have been classified according to the NEN-EN-60825 standard into 4 main categories whereby the risk for the user increases per category. Most categories are subdivided into two sub categories on the basis of their power, resulting in 7 categories. With pulse lasers this is based on energy and length of the pulse. With continuous-wave lasers the classification is based on the power of the beam and on the visible wavelength area, partly on the presence of the eye-close reflex.
The classification of the laser needs to be based on the maximum beam capacity. In fixed set-ups where the laser is not used at maximum capacity, the set-up can be classified in a lower category, subject to whether sufficient measures have been taken to ensure that the capacity of the departing beam cannot become higher than the maximum capacity of the lower category concerned.

The classification into 7 categories is as follows.

Category

Safety

Description

1

Safe

Concerns lasers with a wavelength both in the visible and non-visible spectrum. Under normal circumstances these lasers are safe for eyes and skin, even when optical instruments are used. A product can contain a laser of a higher category, but the electronics keep the radiation below the upper limit of category 1 lasers.

1M

Caution

With normal use, these lasers are safe in the wavelength area of 300 to 4000 nm, but are dangerous when using optical instruments, for example if diverging lenses are used within 10 cm of the laser opening or if a broad beam can hit an eye by aiming at it and through optics.

2

Safe

The beam of low-power lasers (lower than 1 mW) falls within the wavelength area of 400 to 700 nm. These lasers are safe because when exposed

during normal use the head timely turns away from the source and an eye reflex takes place immediately (within 0.25 sec.).

2M

Caution

As under category 2: the beam of this laser falls in the wavelength area of 400 to 700 nm. However, these lasers are dangerous when using optical instruments (see also category 1M).

3R

Potential danger

These lasers are dangerous in the wavelength area between 300 and 1*106 nm when looking straight into the laser beam. The maximum emission (AEL = Accessible Emission Limit) is five times higher than for category 2 lasers in the visible wavelength area and fives times higher than for category 1 lasers in the other wavelength areas.

3B

Immediate danger

The beam of lasers from this category poses

an immediate danger both in the visible and non-visible area when looking into the beam.

4

Very dangerous

These lasers pose a danger under all circumstances, including the diffused reflected beams. They can cause injury to eyes and skin, but may also cause fire.

Attachment 2 - Log format

Type of laser

Risk category

Laser users

Reason for use of laser

Location