Mineral Case housing rock samples which fluoresce and phosphoresce

Natural History Museum: Earth Galleries Update (Earth's Treasury)

The tank houses various rock samples, some of which phosphoresce after being subjected to UV light and others which fluoresce whilst being subjected to UV light. The samples are cyclically illuminated between UV, darkness and white light. 

The exhibit is inherently safe since the tank itself uses a special laminated glass, which prevents any potentially harmful UVA and UVC radiation from escaping. An ozone (by product of UV lighting) control device is built-in, it measures levels of ozone and operates a ventilation system with a fail-safe override.

Control

5 microprocessor controlled gobos (rotating disc with an aperture) are used to sequence the lighting. These are flush mounted to the ceiling of the case. The gobos are controlled using an RS485 serial communication channel from a wall-box controller, which also allows local adjustment of all the transition times and duration periods. The gobos are switched on and off, synchronised and reset according to messages sent from the controller. 

The system used here can be adapted or expanded (e.g. up to 256 gobos can be driven by a single wall-box controller) for use in other installations.
 

Wall-box Controller

Gobo