Visible light transmission is the ability of a material to let visible light pass through it. In practice, it is what makes glass appear clear instead of opaque or tinted. Materials with high visible light transmission are useful when designers want a surface that can be seen through while still adding another function, such as sensing, filtering, or display behavior.
In cyber security, this matters because many modern interfaces hide electronics behind transparent materials: touch panels, smart windows, access terminals, and protective covers. If a coating or layer reduces visible light transmission too much, the device becomes harder to use or inspect. If the material is clear but poorly engineered, it can still weaken reliability by making touch or status cues less obvious. Security reviews therefore look at the full stack: optical clarity, electrical performance, durability, and whether the surface reveals enough state for users and operators to trust it. In attacks, attackers may exploit obscured indicators or tampered overlays; in defenses, high-transmission materials help keep controls readable while preserving tamper-resistant construction.