A laser welding operator, a worker standing beside the machine and a technician who has just opened the enclosure face three very different exposures to the beam. The market usually gives all of them the same answer: "get OD7 glasses". That answer is incomplete.
A fiber laser beam is invisible, gives no warning such as glare before it does harm, and is focused onto the retina. Eyewear built for the wrong wavelength offers practically no protection, whatever number is printed on it. This guide shows which specifications to check, why OD alone is not enough, and when eyewear is not a sufficient answer at all.
The short answer, if you are in a hurry
- First get the wavelength from the source datasheet, then confirm it falls inside the eyewear's protected band.
- OD tells you how much light is attenuated, not whether the filter survives the beam. The LB rating in EN 207 tests both.
- A tenfold increase in power raises the required OD by only about one unit. The real issue with multi-kilowatt lasers is filter endurance and beam-path control.
- Eyewear is the last line of defense. It does not replace an enclosure, interlocks, laser curtains or a controlled area.
Contents
- Why are eyes so vulnerable to fiber lasers?
- Wavelength: the first criterion
- What OD means: OD5 vs OD6 vs OD7
- Why OD cannot be read from kilowatts
- EN 207 and the LB rating
- Enclosed cutting, open-bed cutting and handheld welding
- VLT and operator vision
- Buying checklist
- Care and replacement
- Frequently asked questions
Why are eyes so vulnerable to fiber lasers?
Visible and near-infrared light passes through the cornea and lens, and the lens focuses it onto a tiny spot on the retina. A fiber laser beam at around 1070 nm sits exactly in this range. Far-infrared radiation, such as a CO2 laser, is by contrast mostly absorbed in the front of the eye.
Two characteristics make the hazard more serious:
- The beam is invisible: an operator cannot see a 1070 nm beam or its reflection. A red or green guide light tells you nothing about the power or the hazard path.
- Long hazard range: for a 100 W Nd:YAG laser, OSHA's manual cites an eye hazard distance of 792 to 1,410 m for direct viewing and 0.8 to 1.4 m for diffuse reflection. A fiber source manufacturer also speaks of eye hazards at distances of hundreds of feet for handheld welding. These figures depend on the beam, but they show that "being far from the machine" is not a safety criterion.
Wavelength: the first criterion for choosing eyewear
Laser eyewear is a filter designed for a specific part of the spectrum and promises nothing outside it. So before anything else, take the wavelength from the source datasheet, not from a guess or an advert.
| Laser type | Approximate wavelength | Typical use |
|---|---|---|
| Industrial fiber laser | 1064–1080 nm | Metal cutting and welding |
| Nd:YAG | 1064 nm | Welding and materials processing |
| CO2 laser | 10,600 nm | Cutting and engraving non-metals |
| Green laser | 532 nm | Marking and micromachining |
| UV laser | 355 nm | Marking and precision processing |
Two common mistakes:
- Treating fiber and CO2 eyewear as the same. CO2 eyewear does not necessarily protect at 1070 nm, even with a high OD printed for 10,600 nm. The reverse is also true.
- Ignoring the edge of the band. Eyewear specified only up to 1064 or 1070 nm may not be documented for a 1080 nm source. On some spec sheets the protection figure differs between two parts of one spectral band, so read the number at your own machine's exact wavelength.
To learn more about source specifications, see the fiber laser source buying guide.
What OD means: OD5 vs OD6 vs OD7
OD, or optical density, shows how much a filter reduces radiation at a specific wavelength. Each one-unit increase cuts transmitted light tenfold:
| Rating | Attenuation factor | Transmission |
|---|---|---|
| OD4 | 10,000× | 0.01% |
| OD5 | 100,000× | 0.001% |
| OD6 | 1,000,000× | 0.0001% |
| OD7 | 10,000,000× | 0.00001% |
| OD8 | 100,000,000× | 0.000001% |
This table is only the mathematics of attenuation. OD7 means nothing outside its specified wavelength band, and it says nothing about how the filter behaves under a powerful beam. Higher OD is not always better either: a darker filter usually reduces vision, and poor vision is itself a cause of error.
Why OD cannot be read from kilowatts
No standard contains a table saying "3 kW means OD6 and 6 kW means OD7". The underlying method compares the worst credible exposure with the maximum permissible exposure (MPE):
To see the relationship, here is an illustrative calculation. Assume the whole continuous fiber beam enters the 7 mm pupil aperture (the worst case), and take the 10-second MPE from OSHA's table for 1064 nm, which is 5.1 mW/cm²:
| Source power | 1 kW | 2 kW | 3 kW | 6 kW | 12 kW | 20 kW |
|---|---|---|---|---|---|---|
| Calculated OD | 5.7 | 6.0 | 6.2 | 6.5 | 6.8 | 7.0 |
This is not a buying table. It shows one important result: when power rises twentyfold, the required OD rises by about 1.3 units. OD grows logarithmically with power. This fits practice, where a source manufacturer recommends OD 7+ for handheld welding and another supplier treats OD 6+ as the minimum for 2 kW welding.
An older OSHA table (29 CFR 1926.102, the construction standard) converts power density to OD, but it stops at 10 W/cm². A 1 kW beam through a 7 mm aperture is about 2,600 W/cm², far outside that table.
So for kilowatt lasers the right question is not "how much OD?" but "how long does the filter survive at this power density?"
EN 207 and the LB rating: what OD does not tell you
OD is an optical property, but under a beam a filter can burn, melt or lose its properties. Lasermet gives a clear example: polycarbonate eyewear with OD above 6 at 10,600 nm looks on paper as if it would easily stop a 20 W beam, yet the same beam burns it almost immediately.
In EN 207, the filter and frame are tested under real radiation. An LB number means the filter has the required OD and also stayed intact at a defined power or energy density for a short test period. So LB6 includes at least OD6, but the reverse is not true: OD6 eyewear is not necessarily LB6.
| Letter | Radiation type | Pulse duration |
|---|---|---|
| D | Continuous wave (CW) | Over 0.25 s |
| I | Long pulse | 1 µs to 0.25 s |
| R | Q-switched pulse | 1 ns to 1 µs |
| M | Ultrashort pulse | Under 1 ns |
Reading an example marking: 1064–1080 D LB6 means the filter was tested in this band, for continuous radiation, at level 6. If your laser is pulsed, the D mark alone is not enough and the letter matching your pulse is also required. This matters for marking lasers and pulsed welding.
For continuous radiation from 315 to 1400 nm, the power density for level n is 10n+1 W/m². The table below shows how much the beam diameter at the eyewear matters:
| Beam diameter on the filter | 1.5 kW | 3 kW | 6 kW | 12 kW |
|---|---|---|---|---|
| 200 mm | D LB4 | D LB4 | D LB5 | D LB5 |
| 50 mm | D LB5 | D LB6 | D LB6 | D LB6 |
| 7 mm | D LB7 | D LB7 | D LB8 | D LB8 |
| 1 mm | D LB9 | D LB9 | D LB9 | D LB10 |
Figures are approximate and for understanding only. Beam-diameter correction factors are not applied and the whole beam is assumed to hit the filter. The final choice must follow the standard's own selection annex and a risk assessment.
This table also shows the root of a hazard: near the focal point the beam is narrower than 1 mm and the power density goes beyond the top of the scale. No eyewear is designed for that exposure. The scope of EN 207 is also accidental exposure, not looking at the beam or standing in it.
Two further notes: ISO 19818-1:2021 is the newer international standard in this field and has replaced EN 207 and EN 208 in some countries, so you may see either on a product sheet. Eyewear sold for the US market is usually specified by OD under the ANSI Z136 framework and does not necessarily carry an LB mark.
Enclosed cutting, open-bed cutting and handheld welding: three different scenarios
Two machines with the same source can have completely different safety requirements. OSHA also stresses that other controls should provide the primary protection rather than reliance on eyewear.
Cutting machine with a fully closed cabin
If the manufacturer has documented the complete machine as Class 1, the operator's safety in normal work comes from the cabin, the dedicated window and the door interlocks, not from eyewear. This changes during service: once a panel is opened or an interlock is defeated, work happens under Class 4 conditions and needs a written procedure, suitable eyewear and a responsible person. To understand the classes, read laser classes vs. laser types.
The cabin viewing window is a separate matter: ISO 19818-1 explicitly excludes equipment viewing windows from its scope. Obtain a replacement window only to the machine manufacturer's specification, not as a similar tinted sheet.
Open-bed cutting machine with no cabin
This setup is common in workshops and is often left out of guides. Such a machine is not Class 1. Although the beam points downward, reflections from the sheet, the cut edge and tipped-up parts can threaten the area around the table. It needs a risk assessment, a barrier or laser curtain, and suitable eyewear for anyone inside the hazard zone.
Handheld laser welding
This is the most sensitive scenario: the beam path is open, the head is in the operator's hand and the angle keeps changing. Shiny metals reflect well at 1070 nm. The minimum requirements, according to a source manufacturer's guidance, are:
- Controlled area: a room or enclosure with barriers and curtains rated for Class 4 at your power, warning signs and access control. Add a roof if the area can be seen from above.
- Eyewear for everyone: anyone in direct or indirect line of sight of the beam and its reflections, not only the welder.
- Laser welding helmet together with eyewear: laser eyewear gives limited protection against the bright visible light of the plasma, and an arc welding helmet does not replace laser eyewear. The welder needs both layers.
- Clothing: full skin coverage in heat-resistant, non-synthetic fabric.
- Fume extraction: eyewear does nothing for the respiratory hazard.
See machine setup in the handheld laser welder user guide and process basics in what is fiber laser welding?. Before buying a machine, budget for this equipment too; the pre-purchase FAQ will help.
VLT and operator vision
VLT is the percentage of visible light passing through the lens, a separate number from protection at the laser wavelength. Two pairs with the same OD can have very different VLT. Eyewear that is too dark tempts workers to lift it to see the part, or leads to errors, and that is a hazard in itself.
For a dim workshop, look for a higher VLT, and for precise part setup consider color perception too. Try the eyewear under your real workshop lighting before buying.
Laser safety eyewear buying checklist
Get this information from the seller in writing before you buy:
- The protected wavelength band, which must include your source's datasheet wavelength.
- OD at that exact wavelength, not the peak value on a chart.
- The EN 207 or ISO 19818 marking with the radiation-type letter and LB number, or equivalent specifications with test documents.
- Manufacturer name, model and traceability; the label on the eyewear itself should show wavelength and OD.
- The VLT value.
- Side protection, frame coverage and compatibility with prescription glasses.
- Any limits the manufacturer states on power and exposure time.
- Compatibility with the welding helmet and other equipment.
Care and replacement
Check the lens and frame before each use:
- The lens has no cracks, deep scratches or burn marks, and no unusual color change.
- The frame is intact, with no gap between lens and frame.
- The wavelength and OD label is legible.
- The eyewear sits properly on the face, with no radiation entering from the sides.
Clean eyewear as the manufacturer recommends and store it in its case. Some filters change properties under intense radiation or over time, so if a pair has taken a direct beam, remove it from use even if it looks intact.
Frequently asked questions
Is OD6 eyewear enough for a 6 kW laser cutting machine?
Power alone cannot answer this. First find out whether the machine is an enclosed Class 1 cabin or an open bed, what the source wavelength is and what exposure is credible. For worst-case exposure to the full beam, OD6 is below the calculated figure and needs closer review.
Is OD7 better than OD6?
At a given wavelength it transmits ten times less radiation, but that does not mean the filter lasts longer or suits your work better.
Can one pair cover both fiber and CO2 lasers?
Only if the technical documents confirm sufficient protection at both wavelengths. A high number for one says nothing about the other.
Is a laser welding helmet enough?
The helmet and eyewear are two separate layers. Manufacturers' guidance for handheld welding usually calls for a laser-rated helmet together with laser eyewear; check your own helmet's specifications as well.
Must a laser cutting operator always wear eyewear?
It depends on the machine. On a documented Class 1 machine, in normal work with the door closed, the cabin is the main protection. On an open-bed machine or during service, the answer differs. The basis is the risk assessment and the manufacturer's documents.
Can eyewear still be used after taking a direct beam?
No. Set it aside and check it against the manufacturer's specifications.
Sources
- OSHA Technical Manual, Section III, Chapter 6: Laser Hazards
- OSHA 29 CFR 1926.102: Eye and Face Protection
- UC Berkeley EH&S: Selection of Laser Safety Eyewear
- Lasermet: EN 207, CE Marking and Laser Protective Eyewear
- IPG LightWELD: Handheld Laser Welding Safety
- ISO 19818-1:2021, EN 207, IEC 60825-1, IEC 60825-4, ISO 11553-1 (check the current edition)
This article is educational guidance and does not replace a risk assessment, the manufacturer's instructions or the advice of a laser safety officer.