Visible Light Transmission, or VLT, refers to the percentage of visible light that passes through a lens. It is commonly listed in laser safety eyewear specifications and can significantly affect the user experience.

A higher VLT allows more visible light to pass through the lens, creating a brighter viewing experience. Lower VLT values generally result in darker lenses.

The VLT of a laser safety filter depends on the wavelength protection required. Some filters can provide high optical density while maintaining relatively high visibility, while others require darker lens designs to achieve the necessary attenuation.

It is important to understand that VLT and laser protection are different measurements. A lens with a high VLT can still provide excellent laser protection if it is designed for the appropriate wavelength.

Understanding VLT helps users balance laser safety requirements with comfort and visibility in their working environment.