Laser safety glasses filters typically come in three types and which one you need depends on the specific requirments: Polymer filters are lightweight, comfortable to wear and offer the highest impact resistance. They are also the most cost-effective option. The filter material extends all the way through the filter which is often 2-3mm thick. This type of filter is the most popular and is used with all laser types and applications.
Filter glass lenses. These are more expensive than polymer filter lenses, however, have a significantly higher (often clear) visibility, this can be important in situations that require a high degree of visibility or colour clarity, such as in medical or telecom applications. Specialised glass filter material is used that composes the whole lens and is designed to absorb at specific wavelengths.
Dielectric coated lenses. They provide a very narrow band of wavelength protection, therefore, give a high level of visibility. The coating works by reflecting the laser wavelengths, however, because the coating is only applied to the surface, scratches can reduce the performance of the filter. Dielectric coated lenses also tend to be the most expensive option due to the involved manufacturing process.