A novel ‘‘point‐diffraction’’ interferometer has been implemented on the Los Alamos solid fiberZ‐pinch experiment. The laser beam is split into two legsafterpassing through the plasma. The reference leg is filtered with a pin‐hole aperture and recombined with the other leg to form an interferogram. This allows compact mounting of the optics and relative ease of alignment. TheZ‐pinch experiment employs a pulsed‐power generator that delivers up to 700 kA with a 100 ns rise time through a fiber of deuterium or deuterated polyethylene (CD2) that is 5‐cm long and initially solid with radiusr≊15 &mgr;m. The interferometer, using a &Dgr;t≊200 ps pulse from a Nd:YAG laser frequency doubled to &lgr;=532 nm, measures the electron line density and, assuming azimuthal symmetry, the density as a function of radial and axial position. Calculations predict Faraday rotations of order &pgr;/2 for plasma and current densities that this experiment was designed to produce. The resulting periodic loss of fringes would provide the current density distribution.