Holography:

Transmission  and reflection copies  

Mastering in photo-resist

Holographic Optical Elements (HOEs)

Air current compensation

Never-fail classroom holograms

Thermal drift compensation

Interferometry:

Real time vibration monitoring

Lock fringes for data collection

LUPI (laser unequal path interferometer) fringe locking

Lasers:

Lock two lasers together to get a single mutually coherent beam 

Laser frequency drift compensation: lock the laser frequency by

locking the fringes caused by frequency drift in the laser cavity