We welcome suggestions for topics and content.
Previous Issues are available.
Initial tests of a new system for mirror positioning on the infrared beamline, Beamline 1.4, have shown that it reduces photon beam intensity fluctuations by an order of magnitude. The system uses visible light from the ALS and a position-sensitive detector as feedback to control the angle of the beamline's fifth mirror. The mirror is mounted on a two-axis piezoelectric stage that moves to maintain a consistent beam position relative to the detector. A subsequent mirror reflects the infrared light but allows the unwanted visible light to pass through. Preliminary tests showed a ten-fold decrease in intensity fluctuation at frequencies up to 100 Hz and some correction up to about 800 Hz.