Always consult your Laser Safety Officer (LSO) or another qualified laser safety professional when selecting laser safety eyewear. Required wavelength protection and optical density (OD) depend on the specific laser and reasonably foreseeable worst-case exposure conditions. Do not select laser safety eyewear based on laser type or wattage alone.
Many K40 CO₂ laser cutters are specified to operate at approximately 10,600 nm (10.6 µm). However, always verify the actual operating wavelength specified by the manufacturer before selecting laser safety eyewear.
Laser safety glasses must provide protection at the actual laser wavelength and have sufficient optical density (OD) for the reasonably foreseeable worst-case exposure conditions.
The 40 W power rating alone is not enough to determine the required OD. As part of the hazard evaluation, you may find the LIA Optical Density Calculator helpful for evaluating OD requirements.
It is also important to distinguish a laser's classification from its hazard evaluation. Classification describes the laser's general hazard category, while the hazard evaluation considers the specific laser parameters and reasonably foreseeable exposure conditions for the application.
For a more detailed explanation, see Laser Classification vs. Hazard Evaluation: What's the Difference?
If your K40 laser operates at 10,600 nm and your laser hazard evaluation determines that OD 6+ provides sufficient protection, Laser Safety Industries offers CO₂ laser safety eyewear rated:
OD 6+ @ 10,000–11,000 nm
This range includes 10,600 nm.
For a more detailed explanation of wavelength, optical density, and CO₂ laser eyewear selection, see our guide: What Safety Glasses Do I Need for a CO₂ Laser?