  Several relatively small-scale experimental setups aimed on prototyping of
future laser gravitational-wave detectors and testing of new methods of quantum
measurements with macroscopic mechanical objects, are under development now. In
these devices, not devoted directly to the gravitational-wave detection,
Mach-Zehnder interferometer with pass-through Fabry-Perot cavities in the arms
can be used instead of the standard Michelson/Fabry-Perot one. The advantage of
this topology is that it does not contain high-reflectivity end mirrors with
multilayer coatings, which Brownian noise could constitute the major part of
the noise budget of the Michelson/Fabry-Perot interferometers.
  We consider here two variants of this topology: the "ordinary" position meter
scheme, and a new variant of the quantum speed meter.
