What is Wavelength?

Wavelength is the distance between repeating units of a propagating wave of a given frequency. What makes a laser unique is that usually has very specific wavelength(s) that it operates at in the Electromagnetic Radiation spectrum. Electromagnetic radiation is classified into types according to the frequency of the wave.

These types include radio waves, microwaves, terahertz radiation, infrared radiation (IR), visible light, ultraviolet radiation (UV), X-rays and gamma rays. Radio waves have the longest wavelengths and Gamma rays have the shortest.

A small window of frequencies, called visible spectrum or light, is sensed by the eye of various organisms, with variations on the limits of this narrow spectrum. Many lasers operate outside the visible spectrum but still require protection... what you can't see will hurt you.

Different wavelengths require specific protection at a particular level. Lasers may also operate at different wavelengths and require different levels of protection at each wavelength. I.e. doubled Nd:YAG laser my operate at both 532 nm and 1064 nm with a required OD of 5 for both wavelengths.

If you laser glasses don't provide protection at both wavelengths you will need two different pair of eyewear. The color of the lens in laser safety glasses or goggles does not determine the wavelengths that it offers protection from.

Most laser glasses offer specific wavelength protection to provide the best visible light transmition. Do not assume that laser glasses offer protection from all lasers!