A holographic lateral shearing and conventional interferometer for studying PRS loads

Abstract

Summary form only given. A multiple reference beam holographic system has been developed to study PRS loads. This diagnostic employs three, spatially distinct reference beams that are used to create three holograms stored on the same film plate. One of the holograms records the undistorted laser wavefront (reference), while the other two record the distorted laser wavefront after passage through the plasma at two different times on the same shot and along the same path. An optical time delay of up to 50 ns is implemented using a polarizing beam-splitter, two steering mirrors, and a pair of prisms. The use of spatially distinct reference beams during hologram formation allows one independent access to each of the images when the hologram is reconstructed. As a result conventional interferograms and lateral shearing interferograms can be reconstructed from the same exposure. During reconstruction, one can also adjust the frequency and orientation of background fringes for conventional interferograms as well as the shear angle and direction for shearing interferograms. Only minor changes in the optics are required to switch between the two analysis modes. At the heart of the diagnostic system is a 170 ps, 250 mJ pulsed Nd:YAG laser that uses a doubling crystal to operate at 532 nm. Examples of reconstructed interferograms will be presented.