Holographic polaro‐interferometry represents a flexible tool for studying density and magnetic fields in an ICF plasma. The polarization and the changes in beam phase are recorded in a single hologram. Using the polarization information, the magnetic field (i.e., the Faraday rotation) of the plasma can be determined, while the density profile can be inferred from the change in beam phase. The experimental setup uses a Mach–Zender arrangement to form the hologram/interferogram. A single beam is passed through the plasma. This beam is split when entering the Mach–Zender arrangement. The reference beam is passed through a spatial filter to erase phase information generated from the passage through the plasma. This diagnostic is being developed for application to ICF plasmas. It will be tested initially on a long‐scale length plasma generated by an exploding wire. An interferogram is presented.