Cleaning optics

[LewisM]

Go on, I dare you :)

http://www.nasa.gov/image-feature/goddard/engineers-clean-mirror-with-carbon-dioxide-snow

[sn1987a]

close enough?. :P

[hobbit]

Just hang on while I grab an extinguisher.

[DavidTrap]

Apparently works fine, until the dust on a mirror is turned to mud by dew...