Glossary · Accessories
Laser safety glasses
Special glasses that block exactly the light of your laser. They protect only if they match the wavelength and filter strongly enough.
Explained in more detail
Laser safety glasses filter a specific wavelength range. How strongly is given by the optical density (OD): OD 4 lets through 1/10,000, OD 5 only 1/100,000. For diode lasers around 450 nm with several watts, OD 5 or more is usually recommended, and 1064 nm and 10,600 nm each need their own filters. In Europe, laser safety glasses are tested to EN 207 and marked with the mode of operation, wavelength and protection level, for example "D 445 LB5". The LB protection level roughly corresponds to the optical density, but it also takes into account how long the filter withstands the beam.
Where does the term come from?
Optical density is the base-10 logarithm of the ratio of incident to transmitted light. The abbreviation OD comes from the English optical density, and LB in EN 207 stands for the protection level.
In practice
- Check the marking on the glasses or filter: your laser wavelength must lie within the stated range, with a sufficient protection level.
- The green or orange glasses supplied with some inexpensive devices often have no traceable marking. If in doubt, replace them.
- Glasses for 450 nm do not protect against 1064 nm. With combination devices you need protection for both wavelengths or two pairs of glasses.
- Replace scratched or damaged filters, as the protection is then no longer reliable.
Not to be confused
Sunglasses or ordinary workshop safety glasses do not protect against laser radiation. The colour of the lenses also says nothing about the protective effect.
Frequently asked questions
Which laser safety glasses do I need for a diode laser?
Glasses marked for 445 to 455 nm and at least OD 5 or protection level LB5. For machines with an additional infrared module, they must also cover 1064 nm.
What does OD mean on laser safety glasses?
OD stands for optical density. Each step filters ten times more strongly: OD 5 lets through only one hundred-thousandth of the laser light.