High-sensitive multi-pass imaging interferometry of a gas/plasma jet.

To increase the sensitivity of optical interferometry for diagnostic of gas/plasma jet density with weak refractivity, we realize several multi-pass probing setups with the visualization field. These optical setups are based on a modified Michelson interferometer with multi-pass and multi-angle propagation of the probing beam through the transparent inhomogeneity. In comparison to the standard single-pass Mach-Zehnder setup, the multi-pass interferometer allows for an increase in the measurement sensitivity of up to 8 times. This technique can be applied to a transparent axially symmetrical gas/plasma jet with low refractivity.