HEALTH & SAFETY
1-14 EPT031055 Issue 2 September 2017
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.
Materials
All guard materials must be opaque to 1040 to 1200 nanometers and to 630
to 670 nanometers wavelength laser light, produced by the fibre laser or
pilot laser. Guards may be metallic and non-reflecting, however if a see-
through guard is required, a material opaque 1030 to 1200 nanometers
wavelength laser light must be used.
See through guards must be special laser safety windows.
Always use non-reflecting materials.
The thickness of the guard material depends on the mechanical strength
required, and the amount of ‘burn through’ anticipated. For the purpose of
adequate mechanical rigidity, a thickness of at least two millimetres
(preferably three millimetres) of steel plate is recommended. To ensure laser
safety, a greater thickness of the guard material may be required.
In a fault condition, these materials withstand the laser beam for a limited
time before the beam burns through. The laser must therefore be monitored
to avoid a risk of fire.
A ceramic or metal plate may be used as a beam stop. A greater thickness
is required to achieve the “eight hour burn through” requirement.
Guidance regarding laser guards can be found in EN60825-Part 4.
Beam Delivery Cable (Fibre)
The beam delivery cable is not Class 1 under a worst case single fault, no
cable break or fibre break detection is offered on this product. The
integrator must either include the beam delivery cable inside the Class 1
enclosure with the Pulsed Laser Aperture, or undertake suitable measures
to ensure that under reasonable and foreseeable use, the cable is suitably
positioned to prevent it from becoming damaged or mishandled.
Substrate
Laser Beam Path
Access Guard
Laser Head
Lens
Beam Stop
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