Patent ID: 7880861

Claim:
A method for synchronizing a plurality of nodes in a lithography system, comprising: from a controller node in the lithography system, transmitting a master trigger downstream to first and second local nodes in the lithography system coupled in series; measuring a downstream arrival time of the master trigger (Td n ) at the first one of the local nodes (n) and retransmitting the master trigger downstream to the second one of the local nodes (n+1); transmitting the master trigger upstream from the second one of the local nodes (n+1) to the first one of the local nodes (n); measuring an upstream arrival time of the master trigger (Tu n ) from the second one of the local nodes (n+1) at the first one of the local nodes (n) and retransmitting the master trigger upstream to the controller node; and calculating a local synchronization time signal (T synch(n) ) based on a differential measurement between Td n and Tu n , thereby synchronizing the first and second local nodes with the controller node.