UV - Ultra violet
Ultraviolet - the part of light spectrum that is beyond violet. It’s a light that humans cannot see, but does make some things glow. It can be use to cure plastics and resins, to erase certain types of computer memory, and is part of PCB making processes. These uses come up in robotics and robot building.
It is used in the manufacture of PCB’s when using photoresist, a layer of UV sensitive material. The UV light is used to expose the photoresist, and the unexposed areas are then washed away. This leaves the pattern of the PCB tracks on the board. This is a very common method of making PCB’s, and is used in industry and by hobbyists.
It is also used to clear data left on older EPROM chips, and can still be used to do the same with EEPROM chips. This also means that for some modern chips, like the die-on-board chips, exposure to UV light can cause them to misbehave, as was seen with exposing some Raspberry Pi boards to a camera flash.
It can also be used to cure plastics and resins, either for resin casting systems, or in 3D printers. SLA 3D printers use UV light to project patterns into a pool of resin, which then hardens. This is a very fast way of making 3D prints, but the resin is expensive, and the prints are not as strong as those made with FDM printers.
It is not normally used in sensor technology - as it is considered more harmful or intrusive than IR. However - it can be used to reveal things not normally visible in ambient light, for example ultra-violet is used in machines that check the validity of monetary notes.