LIGHT STRIKES THE BEAT
Realization of the metre in a PTB
quantum optics lab. A laser wave-
length standard with a stabilized,
frequency doubled Neodym:YAG-
Laser produces light of a specific
frequency for interferometric length
measurement. The three glass
cylinders contain gaseous iodine
which, analogous to a tuning fork,
provides the reference frequency
to which the laser is tuned.