With the development and application of laser technology, laser safety protection products are widely familiar and
adopted by people. According to the protection principle, laser protection products can be divided into: reflective
type, absorption type, photoelectric switch type, grating type, etc. Among them, the photoelectric switch type and
grating type are difficult to be widely used due to slow response time and inconvenient wearing.
Reflective and absorptive laser protective glasses are more common on the market now. Then, let’s briefly introduce
the protective technology and principles of these two protective glasses.
Reflective laser protective glasses were developed and applied in the 1970s. The principle is to coat the surface of the
lens with a light reflective film corresponding to the laser wavelength, and reflect the incident light through the reflective properties of the material to achieve protective effects.
| Item | Reflective Glasses | Absorptive Glasses |
| Visible light transmittance (VLT) | High
| Lower |
| Visual Impact | Low | High |
Optical Density
| Lower | High |
| Protection Angle | Limited Angle | All-round protection |
Resistant to Environmental Influences | Less | Better |
| Prevent Secondary Damage | Less
| Better |
Due to the principle of reflective optical film coating, reflective protective glasses have a high visible light transmittance,
which can reach VLT ≥ 80% and the light transmittance color is light, so they have little visual impact on the human eye.
However, the reflective film has a big weakness, that is, its protective effect depends on the angle of the incident light
source. When a light source enters from one medium into another, total reflection will occur only when the incident
angle is greater than a certain critical angle, otherwise some light will "escape". This is also what we call, the reflective
film has a certain selectivity for the incident light source.
At the same time, the protective film layer is affected by environmental humidity, temperature, and time and is easy to fall
off. Therefore, its protective behavior ability has certain limitations.
