Fast Feedback Systems for Lasers to Increase Stability and Control

d. Fast Feedback Systems for Lasers to Increase Stability and Control Laser applications to accelerators and other systems demand increased precision. This requires correction for variations in the laser delivery parameters resulting from environmental factors such as fluctuations in temperature, sound, vibrations, changes in duty factor, and humidity. The environmental factors are typically dominated by <100 Hz spectral components (e.g., mirror mounts in the transport may have a vibrational resonance at ~40 Hz) and are thus well-suited to be compensated with fast feedback systems. Currently, many higher power ultrafast lasers operate at repetition rates below 10 Hz, but typically there are alignment lasers present along the beam line all the way to the interaction point that can be used for control. In the longer term, laser system repetition rates of kHz and 10's of kHz are expected. Grant proposals are sought to develop fast feedback systems to correct laser parameters such as a transverse position and pointing angle of the laser at the final focus. The complete system would include sensors (non-perturbative), actuators, and a fast control system. Threshold. Proposals must aim, at a minimum, to provide a pointing stability of better than 2 micro-radian RMS, measured at the final aperture before the laser interacts with its intended target, and must do so under VC-A vibration conditions or worse. Feedback system must recover automatically (e.g., from momentarily blocked laser beam) within 100 msec or 100 laser pulses (whichever is faster) without manual intervention. Objective. Priority will be given to proposals that also correct 5-100 Hz jitter in wavefront and transverse mode content, with wavefront stabilized to 0.95 under VC-A vibration conditions or worse. Questions Contact: Eric Colby, eric.colby@science.doe.gov