While plastic viewing windows meet the minimum requirements for laser safety, they are not as safe as laminated glass. If a stray laser beam makes direct contact with a plastic window, it can quickly burn through and escape the enclosure. For CO2 lasers, laminated safety glass with an optical density of 6+ is recommended. The glass should have a minimum of two layers with a film in between to keep the glass intact even if directly struck by a laser beam or heavy object. Tempered glass is not safe, since it can shatter into small pieces, allowing laser energy to escape. Systems with a fiber laser source should have an additional protective layer, usually tinted blue or green, to contain fiber laser radiation, which is particularly damaging to the eye if viewed directly. If you are not sure what to look for, you can ask the manufacturer for a window safety certification for all laser sources included with the system.
This information originally appears in a Universal Laser System blog post.
—Universal Laser Systems
