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chapter-13-safety-laser-in-research-lab

  • Also see: Laser light conditions & eye injury levelSymptoms of an eye laser burnLaser Power Classes & Safety Glasses, Understanding the eye via laser safety, How to select a laser protective eyewear 

    This chapter aims to provide an overview of the risks associated with the use of laser sources, and give an overview of the European regulations on laser safety, i.e. the directive 2006/25/EC, the Legislative Decree no. 81 / 08 and smi (Legislative Decree no. 106/09) and the laser radiations. Their aim is to protect workers from the risks of exposure to artificial optical radiations.

    For details and further information please refer to the mentioned normative.

    The following points will be discussed:

    • Normative
    • Safety Laser Technician
    • Safety Laser classes
    • Cautions for use in laboratory
    • Laser Safety  Glasses
    • Posters and signs

    We report some articles of the normative, whose non-fulfilment foresees a sanction or the arrest, on charge of the responsible person:

    • The normative assesses the risks associated with the laser systems.
    • The risk assessment must be made by staff with "specific knowledge".
    • The person responsible assesses, measures or calculates the levels of the optical radiations and of the risk of exposure.
    • The workers must never be exposed above the exposure limits, if this occurs, must be immediately taken measures to bring the risk within the safety limits, and to prevent that it exceeds them again.
    • The education, information and training shall be provided to the workers, particularly in relation to the results of the risk assessment.

    The responsible must pay particular attention to:

    • The level, the range of wavelengths and the duration of the exposure.
    • The exposure limit values contained in the related normative.
    • Any indirect effects such as temporary blindness, explosion or fire.
    • The existence of alternative working equipment to reduce the exposure levels.
    • The renewals actions aimed to minimize the exposure levels.
    • The classification of lasers, particularly of class 3B or 4.
    • The information provided by the produers ofthe sources.

    Health surveillance, through medical checkup, is normally carried out on yearly basis, with the aim to prevent and early detect all the negative effects on the health. A medical examination must be performed to the workers whose exposure is detected to be above the limit values.

    The director or the laboratory responsible is responsible for the acquisition and implementation of the necessary safety measures.
    The qualified operators directly involved in the activities, remain responsible for the use of the laser system in compliance with security measures.

    THE TECHNICIAN SAFETY LASER (TSL)

    In the case of research laboratories which use sources and/or laser systems of classes 3R, 3B, 4, it is necessary the appointment or the consultation of a TSL .

    Duties and responsibilities of the Technician Safety Laser
    • support and advise the responsible or the director regarding the safe use of lasers, and the necessary prevention and protection measures;
    • cooperate closely with the laser users;
    • verify the correct functioning of the laser equipment for safety reasons and the law compliance;
    • assess the risks in the laser working area and determine the risk area;
    • identify the proper eye protection;
    • participate in training of the personnel involved with lasers, especially with regard to the risks of exposure and safety measures;
    • ensure that the maintenance and the use of lasers are carried out by trained and qualified persons.


    Requirements of the TSL
    • At least the first level degree in some scientific or technical discipline.
    • Attendance and exam overcoming of a theoretical and practical training course of at least 40 h.
    • Demonstration to have carried out properly documentable activities in the field of laser monitoring.
    • Professional update consisting in attending courses held by experts in the field of laser.

    SAFETY LASER CLASSES

    Lasers have been classified according to the dangerousness of the radiant emission.

    Any commercial laser must be CE marked and furnished with compliant labels, with the exception of class 1 and 1M.
    The laser of class 1 do not imply any restriction.
    For the classes 1M, 2 and 2M are required precautions to only prevent the continuous observation of the direct beam; a temporary exhibition (0.25 s) to radiation in the visible, is not considered dangerous. However the laser beam should never be deliberately pointed toward people.

    Laser devices class 1M and 2 M
    • Do not directly look the beam.
    • Use specific caution for not visible laser radiation.
    • The observation optics at smaller distance than 100 mm, shall be equipped with safety devices (filters, attenuators, etc..)

    Laser devices class 2
    • Do not directly look the beam.
    • Use specific caution for not visible laser radiation.

    Laser devices class 3R
    For laser in the visible and IR should be used luminous warning signals, visible even with protective  Laser Safety glasses. Verbal warnings or luminous signals controlled by the operator himself, may be temporarily allowed for the use of prototypes (previous authorization of the Responsible of the research or teaching Activities in the laboratory).

    • Avoid the eyes direct exposure in the range of wavelengths between 400 nm and 1400 nm and avoid the exposure to the laser beam for the other wavelengths.
    • Use specific caution for not visible laser radiation.
    • Use observation optics (microscopes, lenses, ...) only if equipped with safety devices (filters, attenuators).

     

    Laser devices class 3B
    In addition to those for the lower classes, it must be observed the further following cautions:

    • Use the laser only in the areas controlled by the operators.
    • Avoid specular reflections.
    • Limit the beam with a body made of diffusing material with a color and reflectivity such to minimize the reflection hazards beyond the maximum permissible exposure.
    • Protect the eyes if there exist the possibility to observe the direct or reflected beam.
    • Place warning signal according to the law at the entrance of the areas where the laser is used.

    Laser devices class 4
    In addition to those for the lower classes, it must be observed the further following cautions:

    • Protect the beam path whenever it is possible.
    • Use remote control whenever possible.
    • Avoid the direct, specular and diffused reflections vision of the beam.
    • Take care of the internal illumination of the areas where the eye is protected (e.g. clear walls)
    • In high-power laser, pay sufficient attention to fire risk

    CAUTIONS FOR THE USE IN LABORATORY

    The following table gives an idea of some cautions necessary for the use of lasers depending on the security class to which they belong:

    Any commercial laser must be CE marked and provided with compliant labels, with the exception of class 1 and 1M.

    The classes 3B or 4 lasers must be equipped with key commands. The keys must be removed when the laser is not operating, in order to avoid unauthorized use.
    The cleaning of the laboratories may be made only when the laser is switched off.

    REMOTE LOCK CONNECTOR

    The class 4 lasers, and eventually even the laser of class 3B , must be equipped with safety interlock switches (panic button) easily accessible from the operator station.
    In the research laboratories the connector must be connected to an emergency lock at a distance smaller than 5 m from the area where the activity takes place.

    PERSONAL PROTECTIVE EQUIPMENT - GOGGLES LASER

    The laser radiation can temporarily or irreversibly damage the human biological tissues, particularly the eyes. It is task of the responsible to provide adequate personal protective equipment (goggles), with the advice of the TSL.

    The goggles must be able to filter the light radiation and to avoid the user exposure to a minimum of 10 seconds (D rating), or 100 pulses (I and R rating).


    SOME PROTECTION EYEWEAR

    The goggles must be conform to the normative UNI EN 207 for the total protection, and EN 208 for the alignment. Laser safety glasses must be adapted to the type of laser used.
    The number of scale "L" is the measure of how much protective glasses support the laser radiation. These correspond to 10 levels of optical density of the filter.
    The table is divided into three spectral bands, which take into account the sensitivity of the human eye.

    It is good to know that there are also curtains and shield panels, for example, to separate two areas of the same laboratory certified for safety laser.

    POSTERS AND SIGNS

    On the accesses to the areas containing laser devices of class 3B and class 4 must be placed warning signs.

    Outside the laboratories with laser of class 3R, 3B or 4 must be installed warning light signals, with automatic ignition of the laser.

     

    Bibliography
    "Il tecnico Sicurezza Laser un ruolo chiave in ogni organizzazione che utilizzi laser. Expolaser 2009".

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