Acceleration of Autofocusing Algorithms for Fielding Targets at High-Repetition-Rates

High-power laser systems, used to study high-energy-density (HED) science, are increasingly operating at high repetition rates. This evolution demands equally rapid target fielding and diagnostic methods to ensure experimental efficiency. Common approaches employ tape drive and raster-style target delivery systems; however, our algorithm is versatile enough to field solid targets regardless of the delivery method. Focal image collection is performed by projecting a continuous-wave 532 nm laser onto the target, with a CMOS camera capturing the reflected spot along a co-linear optical path. Our approach computes a composite focus metric by integrating multiple measured quantities—namely, maximum intensity, intensity variance, and the variance of the Laplacian of the image. The gradient of the weighted focus metric is monitored and used to control the optimal location of the target. This feedback mechanism enables focus determination within milliseconds per target location, greatly reducing downtime associated with manual adjustments. This method not only accelerates the focusing process, but also improves the consistency of target fielding location. Experimental data acquired on GALADRIEL will be shown for both tape drive and raster-style target delivery systems for complex foam structures. Validation of these autofocus routines will be correlated with a direct measurement of experimental performance, such as X-ray flux from flat foil targets. By identifying the algorithm that produces the narrowest X-ray flux distribution, we can determine the most effective method for ensuring consistent experimental conditions.