What Laser Safety Window Do I Need for a CO₂ Laser?

If you need a viewing window for a CO₂ laser controlled area or enclosure, the window must provide appropriate attenuation at the actual wavelength produced by the laser.

Many industrial CO₂ lasers operate at or near 10,600 nm (10.6 µm). However, not every CO₂ laser operates at exactly 10,600 nm.

The first step is therefore to verify the laser's actual operating wavelength and make sure it falls within the protection range of the window.

Laser safety windows are wavelength-specific.

A window designed to provide protection from a 1064 nm fiber laser, for example, should not be assumed to provide protection from a CO₂ laser operating around 10 µm.

Similarly, you should not select a window simply because it is described as a "CO₂ laser window."

Instead, compare:

Laser operating wavelength → Window protection range

If the laser operates at 10,600 nm, the window's rated protection range must include 10,600 nm.

If the CO₂ laser operates at another wavelength, that wavelength must also fall within the window's rated protection range.

Matching the wavelength is only the first part of the evaluation.

The window must also provide sufficient attenuation for the potential laser radiation reaching the window.

This distinction is important because a viewing window is not necessarily exposed to the same conditions that might be assumed for direct-beam laser safety eyewear.

A window may be:

The appropriate protection therefore depends on the actual installation and the reasonably foreseeable worst-case exposure at the window.

For more information on eyewear vs window OD see here. We also have a video below:

OSHA's laser safety guidance specifically addresses viewing windows and other optical portals.

OSHA states that viewing portals, optics, windows, and display screens associated with a laser installation should incorporate a means of attenuating transmitted laser radiation to levels below the applicable Maximum Permissible Exposure (MPE).

Importantly, OSHA explains that the filtration requirement for a viewing window is based on the level of laser radiation that could occur at the window under a typical worst-case condition.

This means the evaluation is not simply:

Laser wattage → Window OD

Instead, it is based on:

Laser wavelength + potential exposure at the window → Required window protection

Not based on the 40 W rating alone.

The same principle applies whether the laser is 40 W, 100 W, 500 W, or another output power.

Laser power is an important input, but it does not by itself describe the radiation that could reach the viewing window.

Other factors can include:

For this reason, saying "a 40 W CO₂ laser requires OD X" without considering the installation can oversimplify the hazard evaluation. For more on the difference between a laser class and on a hazard evaluation see here. Also see the video below:

Not necessarily.

Laser safety eyewear and laser safety windows may be evaluated under different potential exposure conditions.

Eyewear may be selected based on a reasonably foreseeable worst-case exposure to a person within the laser controlled area ("LCA""). For more on an LCA, see the video below:

A viewing window, on the other hand, is evaluated based on the laser radiation that could reasonably reach the window at its particular location.

For example, if the primary beam is contained and terminated away from the viewing window, the reasonably foreseeable worst-case exposure at the window may be substantially different from a direct intrabeam exposure.

This is why simply matching the OD of the eyewear to the OD of the window is not always necessary or technically appropriate.

The required protection for each should be determined from its own exposure conditions.

Where the viewing window is installed can have a major effect on its potential exposure.

Consider two windows used around the same CO₂ laser:

Window A is positioned directly along a reasonably foreseeable beam path.

Window B is positioned away from the beam path and primarily receives scattered radiation from the process.

Even though both windows are being used with the same laser, their potential exposure conditions can be very different.

This is one reason laser power alone cannot determine the required window protection.

Start by confirming that the window:

The window should be evaluated as part of the overall laser safety system—not simply as an isolated piece of material.

Many CO₂ lasers operate near 10,600 nm, but do not assume that every CO₂ laser operates at exactly this wavelength.

First, verify the actual laser wavelength and make sure the laser safety window provides protection across that wavelength.

Then determine whether the window provides sufficient attenuation for the reasonably foreseeable worst-case exposure at its installed location.

The basic selection process is:

Verify Laser Wavelength → Evaluate Exposure at the Window → Determine Required Protection → Select the Window

A laser's wattage is an important part of the hazard evaluation, but wattage alone does not determine which laser safety window you need.

Laser Safety Industries offers CO₂ laser safety windows with:

OD 6+ @ 10,000–11,000 nm

This protection range includes 10,600 nm and may be appropriate for many common CO₂ laser applications when OD 6+ provides sufficient protection for the reasonably foreseeable worst-case exposure at the window.

Before selecting this window, verify that:

View CO₂ Laser Safety Windows