Are you planning on installing laser coders on your production lines to add variable information to your packages?
If you are, one of the most important aspects is laser safety.
Uncontrolled laser light can cause eye injuries, burns, or even fires. That’s why there are rules that need to be followed, like the ones set by ANSI, OSHA or the FDA.
Laser Hazard Categories
The FDA categorizes lasers into four major hazard classes, each with specific safety concerns and control measures:
- Considered non-hazardous under normal operating conditions.
- May be hazardous if viewed with optical aids, such as magnifiers or telescopes.
Class II and IIa:
- Emit visible light, typically considered safe for accidental exposure.
- Class IIa lasers have a higher visible light output but are safe for momentary exposure.
- Higher power than Class II and can be hazardous if viewed directly.
- Safe for incidental exposure but may require control measures for prolonged viewing.
- Can cause immediate skin or eye damage upon direct exposure.
- Require strict control measures to prevent exposure.
- Highest hazard class, capable of causing skin and eye injuries from direct and scattered radiation.
- Can pose fire hazards and require extensive control measures.
Packaging lasers are usually part of Class IV, and the object of laser safety guarding is to ensure the finished installation complies with Class I – non-hazardous under general operating conditions.
A laser will always have a label showing the Class it belongs to – this example is from a Domino CO2 laser, and you can see it is classified as a class IV laser product.
The type of guarding needed differs depending on the type of laser that needs to be protected because of the way different light wavelengths behave.
Guarding for CO2 Lasers
CO2 lasers emit light at a wavelength of approximately 9 – 11 microns in the far-infrared spectrum. This light is not visible to us humans. While it can undoubtedly damage eyes or skin with prolonged exposure, CO2 laser light, does not penetrate as deeply as light from other types of laser.
As a result, there are many installations with minimal guarding or even no guarding at all – especially when using low-power lasers.
Perspex, also known as acrylic or plexiglass, is used for guarding CO2 lasers primarily because it is opaque to the specific wavelength range produced by these lasers. Perspex can effectively block the laser radiation, protecting users from potential harm.
When used as a shield, Perspex effectively protects against accidental exposure to the laser beam, preventing eye injuries and skin burns, and its transparency allows operators to see the work process while being protected from laser radiation.
CO2 lasers often use a perspex cone as basic protection, but a full guard of the laser operating area is preferred to meet the Class I requirement.
Guarding for Fiber, UV and Green Lasers
While simple perspex guarding works well with the light generated by CO2 lasers, it is not suitable for the shorter wavelength light produced by Fiber, DPSS, UV and Green lasers.
In addition, laser light of these wavelengths penetrates into the eyes and skin more than CO2 wavelengths – potentially causing damage to the retina. Retinal injuries can be more hazardous than corneal injuries, as they can lead to permanent vision loss.
Ensuring complete guarding for these types of laser is a critical part of the installation since no laser light – either direct or reflected – can be allowed to escape from the system.
The example above shows Domino’s high-speed can coding system that includes full stainless steel guarding.
To prevent any reflected laser light from escaping from the system, baffles are installed within the guards, and the complete guarding system extends far enough from the laser to prevent operators from being able to insert their hands in the area where the coding takes place.
This type of guarding should be used for all fiber, YAG, UV and Green laser installations.
Note that the guarding needs to be interlocked to disable the laser if one of the doors is opened. If the interlocks are overridden (say for setting up the laser head), it is crucial that the operator wears approved laser safety glasses – correct for the wavelength of the light being generated.
The Laser Institute of America provides training and much more for companies that use laser systems.
Listing of laser safety standards