DEVELOPMENT OF TRIGGER AND CLOCK DELAY MODULE WITH ULTRA-WIDE RANGE AND HIGH PRECISION *

Pump and probe experiments using short pulse lasers and synchrotron radiations require precise timing relation between the laser pulse and the RF reference signal of the accelerator. The pulse laser needs clock signal for a mode-locked laser and trigger signal for a regenerative amplifier. The delay time of these two signals were usually adjusted by using a mechanical phase shifter or a cable delay. They have disadvantages of short tuning range or discontinuity in the clock signal. We developed a new delay system, which can continuously change the delay time with the range over 200 ns and the precision better than 3 ps. The key point of the system is combination of an IQ modulator and a synchronous counter. The IQ modulator can change the phase of the RF signal with infinite amount with high precision in ether positive or negative direction. The phase-modulated RF signal is fed to a frequency divider and its output is used for the clock signal of the mode-locked laser. The signal is also fed to the synchronous counter and its output is used for the trigger of the regenerative amplifier. The effectiveness of this system was confirmed by an experiment carried out at the SPring-8. Composition of the delay system, performance and its applications are described in the paper