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INTRODUCTION
GENERAL SAFETY REQUIREMENTS
In the event that a LASER Device is installed on the system, in addition to the usual hazards deriving
from the system functions and operating modes, it is necessary to bear in mind the additional hazards
represented by LASER radiation (electromagnetic radiation, mainly infrared).
The safety of this type of equipment is subject to specific standards, both from the electrical point of view
and from the point of view of radiation (non-ionised).
It follows that careful observation of the technical advice set out in the applicable Standards will lead to a
reduction in the Risk of Exposure to Hazard to levels that are, presumably, compliant with the intention of
the Legislator.
Thus, the manufacturer of the LASER Source, the Party assigned to Install it on the System and the end
user are all responsible for ensuring that the applicable Standards and Regulations are observed.
Thus, rather than a single solution for increasing safety, a variety of different Protection Systems may be
identified.
PROTECTION SYSTEMS
The general rule for protection systems is "... where there is a hazard personnel should not be present, and
where there are personnel, hazards should not be present...".
Hence, it is obvious from the outset that the principal solution for guaranteeing safety is to place a barrier
between personnel and any given hazard, in order to minimise the risk of access. Another solution is to
implement a series of measures designed to notify personnel about the existence of a hazard in order to
prevent them from coming into contact with it inadvertently. Finally, there remains the need for individual
protection measures for those contingencies where the risk may vary according to the operating conditions.
In the case of LASER equipment, three types of protection measures have been identified:
A. Engineering Devices
B. Procedural and Administrative measures
C. Individual Protection solutions
ENGINEERING DEVICES
In the case of industrial environments, the most effective solutions consist of a series of measures
implemented during the design, construction and integration phases with the aim of introducing devices
designed to reduce the risk of exposure to the existing hazards to a minimum. When applicable, this is
achieved by fitting the system with guards that enclose both the LASER and the working area and prevent
hazardous radiation from escaping the enclosure. In this way the acceptable emission limit (AEL) is
reduced to a level such that a LASER classified as hazardous (Class IV) does not emit any more radiation
than a device classified as harmless (Class I).
STANDARD REQUIREMENTS FOR GUARDS
The guards or barriers or enclosures must be designed to intercept the infrared radiation emitted by the
LASER and to resist perforation.
This requirement is easily achievable (in the case of low power LASERS) through the use of sheet metal
panels that shield radiation completely and resist perforation by radiation that is not focused directly on
them indefinitely. In the case of high power LASERS, it is necessary to establish a perforation interval
between one inspection and the next, or implement active casings that are able to detect perforations (by
means of cavities and appropriate sensors).
In the case Nd-Yag Laser equipment, metal panels in NdYVO4 having a thickness in excess of 1.5 mm are
sufficient to resist non-focused radiation generated by the integrated laser source indefinitely.
Access panels and safety locks must be designed to prevent access to hazardous radiation.
Depending on the type of process and/or operation to be carried out on the process, it may be necessary
to remove guards or panels. In such cases, and if the panels are not secured to the structure by means of
screws that require the use of special tools for their removal, such removable panels must be fitted with
safety locks which, when engaged, reduce the radiation to permitted levels.
This is normally achieved by means of an electrical interlock connected to the LASER excitation system
power supply. Since the purpose of the interlock device is to guarantee the safety of personnel, it must
conform to the applicable standards and be approved for use in such applications.