Visible Light Transmission, or VLT, refers to the percentage of visible light that passes through a lens. It is commonly listed as part of the specifications for laser safety glasses.

A higher VLT percentage means more visible light passes through the lens, resulting in a brighter viewing experience. Lower VLT values indicate darker filters that transmit less visible light.

The VLT of laser safety glasses depends largely on the filter technology required to attenuate specific laser wavelengths. Some laser filters naturally allow high levels of visible light transmission, while others require darker lens designs to achieve the required protection.

For example, some laser safety glasses offer VLT levels above 50%, while others may provide less than 20% depending on the wavelength protection required.

VLT does not indicate how much laser radiation is blocked. Instead, it describes the brightness of the viewing experience while wearing the eyewear.

Understanding VLT can help users balance laser protection requirements with workplace visibility and comfort.