Energy conservation and michelson interferometers

[Danyon]

What happens to the energy of a laser beam when it completely deconstructively interferes with itself in a michelson interferometer?

 

[blue_leaf77]

The missing energy goes back to the source. It can be understood from the phase shift attained upon reflection in the beam splitter.

 

[ddesaneis]

Within an interferometer, photon interference causes changes in detect-ability. Collisions between photons do not change energy, except when high-energy photons create matter.
https://en.wikipedia.org/wiki/Two-photon_physics