Optics at the disco

Thinking about going out tonight...?

If so, you might be familiarized with the lights shown in the video.

Sometimes people seem to dance in slow motion, as in the minute 1'02 of the video; the lights responsible of this effect are called stroboscopic lights.

Smoke is also widely used at the disco to produce optical effects: light is slightly dispersed by it and coloured ray traces are easily observed (example: minute 1'14 of the video).

And do you like drinking tonic? If you ask for one at the disco, it can have this appereance:

Don't worry! You haven't asked for the wrong drink and neither have you become colour-blind... It happens because in some discos there are ultraviolet lights (emitting at around 365nm) which excites quinine, a substance contained in the tonic, and producing fluorescence.

Acknowledgments: the author would like to thank B. Hester (from University of Maryland Student Chapter) for her help with the tonic fluorescence.