Introduction
The so-called "goose trigger" is a system where the laser is fed by two triggers that add up to a nominal trigger value (i.e. 9 Hz + 1 Hz = 10 Hz) but the laser to e-beam locking system is only fed by one of those triggers. This allows a user to have some laser pulses synchronized to the e-beam and some not synchronized, or even delayed, with respect to the e-beam. The idea is that you can remove backgrounds if you have laser on and off shots, where the off shots are delayed by ~14 ns so that the amplifiers stay warm.
Trigger System Block Diagram - Goose Trigger
How does the goose trigger work?
When using a "goose trigger", the laser (through the SDG) is fed a signal that is 10 Hz, but only a portion of that 10 Hz is used by the laser timing software. The "gate trigger" on the Keysight box tells the keysight box "start listening for a start and stop trigger". So in the diagram above the Keysight box is only updating at 9 Hz. The "bypass trigger" is a trigger that bypasses the laser timing system, so it can be changed to anything without disrupting the ability of the laser timing system to keep the laser and e-beam in sync.