fotokromatiske

Fotokromatiske refers to a property of certain materials that darken when exposed to ultraviolet light and return to their original clear state when the light source is removed. This phenomenon is known as photochromism. The most common application of this property is in eyeglasses, where lenses are designed to automatically darken in sunlight, reducing glare and providing sunglass-like protection. When the wearer goes indoors or out of direct sunlight, the lenses gradually become clear again.

The mechanism behind photochromism involves molecules within the material that undergo a reversible chemical or physical change upon absorbing UV radiation. This change alters the material's absorption spectrum, causing it to appear darker. The reverse reaction occurs when the UV light is absent, and the molecules revert to their original state, making the material transparent.

The speed at which photochromic lenses darken and clear can vary depending on the specific formulation of the photochromic compounds, as well as ambient temperature. Colder temperatures generally lead to faster darkening and slower clearing, while warmer temperatures have the opposite effect.

Beyond eyewear, photochromic technology finds applications in other areas such as security features on currency and documents, smart windows for buildings that can control light transmission, and in some types of digital displays. The development of photochromic materials continues, aiming for faster response times, a wider range of colors, and improved durability.