UV Pen

KICK ME ↓

— Scrawled on a jacket in UV ink by an impish aven child

An ultraviolet pen is a writing instrument utilizing ink which is reflective only to light in the ultraviolet spectrum. Depending on the type, this ink is not (easily) visible to people without native ultraviolet-sensitive vision, most notably humans.

UV pens are most commonly used by members of species with UV vision,

such as vrans, avens, sphinx, and individuals of other species who have received gene mods or cybernetic implants for it. While usually just a simple writing instrument, UV pens have acquired cultural cachet as pranking tools since most of the Starweb's population cannot see their ink.

Design

Outwardly, they look no different from most other types of pens or markers save for their coloration: quite often, a UV pen's casing will appear white, grey, or some other solid color to those who cannot see the ultraviolet-colored accents on it. Other manufacturers use a paint reflecting a wide-enough spectrum to appear as purple to humans. The ink itself is reflective only in the ultraviolet, and in some cases great care has been taken to make it as hard to see as possible to those without UV vision. Still, in many cases, careful examination of e.g. a sheet of paper with UV writing on it will reveal the ink when viewed under a strong light source.

A similar principle is sometimes used with ultraviolet-only display screens, which without UV vision can appear as featureless white or purple screens, as well as UV-only lights for rooms. In these cases care must be taken to ensure the illumination is kept dim enough that it does not damage the eyes of any persons viewing it.

Though they are easily defeated with technological vision assistance, the obscuration provided by UV pen writing continues to make them a popular prank tool among human-majority cultures. Some polities have laws restricting them and police forces who will view with suspicion anyone caught with one.