Recent advances in automatic alignment system for the National Ignition Facility

Abstract

The automatic alignment system for the National Ignition Facility (NIF) is a large-scale parallel system that directs all 192 laser beams along the 300-m optical path to a 50-micron focus at target chamber in less than 50 minutes. The system automatically commands 9,000 stepping motors to adjust mirrors and other optics based upon images acquired from high-resolution digital cameras viewing beams at various locations. Forty-five control loops per beamline request image processing services running on a LINUX cluster to analyze these images of the beams and references, and automatically steer the beams toward the target. This paper discusses the upgrades to the NIF automatic alignment system to handle new alignment needs and evolving requirements as related to various types of experiments performed. As NIF becomes a continuously-operated system and more experiments are performed, performance monitoring is increasingly important for maintenance and commissioning work. Data, collected during operations, is analyzed for tuning of the laser and targeting maintenance work. Handling evolving alignment and maintenance needs is expected for the planned 30-year operational life of NIF.

Fast implementation of matched-filter-based automatic alignment image processing

“…Automatic alignment (AA) based on computer analysis of video images adjusts the laser beams quickly and accurately enough to meet stringent system requirements in less than 30 minutes. The AA system directs all 192 laser beams along the 300-m optical path to focus on a 50 micron spot at the target chamber center [2]. At the heart of this alignment technique is the image processing algorithm that determines the position of beam features that are embedded in images recorded along the beam path.…”

Autonomous monitoring of control hardware to predict off-normal conditions using NIF automatic alignment systems

“…An automatic alignment (AA) system was developed to process CCD sensor images of the laser beams taken at various locations. The control system uses results of the processing to adjust motorized mirrors within a series of control loops until pre-defined alignment criteria are satisfied [1][2][3]. In addition to providing alignment information, these cameras offer an eye into many aspects of the system health.…”

Image processing and control of a programmable spatial light modulator for spatial beam shaping

“…The key functions of the NIF laser such as specifying pulse shape, alignment, amplification and beam control are managed by the integrated computer control system (ICCS) in order to produce proper timing, high-energy density and pressure leading to a controlled fusion reaction [4][5][6][7]. ICCS divides alignment, optics inspection and shot planning, etc.…”