12 EPT058613 Issue 1 March 2020
ACCESS GUARDS
Access guards are required to prevent direct human access to the laser beam. In practice,
this requires full guarding of the area between, and including, the laser output lens and the
area to be marked on the substrate.
Note: Guarding is required behind the substrate to prevent access to the laser beam when
the substrate is removed, or following accidental burn through of the substrate.
VISOR GUARDS
Visor guards are required to prevent the escape of scattered radiation. Often the access
guarding can be designed to perform this function without the need of an extra guard.
WARNING: Visor guards have to be installed at a minimum distance of four
times the focus distance to the laser beam.
BEAM STOP GUARD
A beam stop guard is required for applications where guarding material is fitted within
100mm of the laser lens focal plane. The beam stop is to prevent burn through of the guard
should the laser be repeatedly operated without the substrate in position. The beam stop
must be capable of absorbing the full output power of the laser for a period of eight hours
and be large enough to cover the complete laser marking field area.
Substrate
Laser Beam Path
Access Guard
Laser Head
Lens
Substrate
Laser Beam Path
Access/Visor Guard
Laser Head
Lens
Scattered
Radiation
Scattered
Radiation
Substrate
Laser Beam Path
Access Guard
Laser Head
Lens
Beam Stop
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