Mach-Zehnder Interferometer

Two beams divided from a single beam transmit different paths, and are recombined by another half mirror to generate interference fringes.
Since optical paths are not returned by a mirror, it is a single path interferometer where a beam passes a sample only once.
A measured value of this interferometer is twice the result of the Michelson or Fizeau interferometer.
It is used for observation of transmitted wavefronts of transmission samples.