LLNL, Livermore, California, USA
Understanding plasma performance in the world’s largest and most energetic laser facility, the National Ignition Facility (NIF), is an important step to achieving the goal of inertial confinement fusion in a laboratory setting. The optical Thompson scattering (OTS) laser has been developed to understand the target implosion physics, especially for under-dense plasma conditions. A 5w probe beams can be set up for diagnosing various plasma densities. Just as the NIF laser with 192 laser beams are precisely aligned, the OTS system also requires precision alignment using a series of automated closed loop control steps. CCD images from the OTS laser (OTSL) beams are analyzed using a suite of image processing algorithm. The algorithms provide beam position measurements that are used to control motorized mirrors that steer beams to their defined desired location. In this paper, several alignment algorithms will be discussed with details on how they take advantage of various types of fiducials such as diffraction rings, contrasting squares and circles, octagons and very faint 5w laser beams.
*This is released as LLNL-ABS-821809
