Extreme ultraviolet light generating system

An extreme ultraviolet light generating system comprising:

• a laser apparatus configured to provide pulsed laser light inside a chamber in which EUV light is generated;
• an optical shutter disposed on an optical path of the pulsed laser light;
• a controller configured to open or close the optical shutter, based on a generation signal supplied from an external unit, the generation signal instructing generation of the EUV light;
• a light emission trigger generator configured to generate a light emission trigger signal and to supply the light emission trigger signal to the laser apparatus, the light emission trigger signal instructing output of the pulsed laser light;
• a target feeder configured to feed a target inside the chamber, the target being to be irradiated with the pulsed laser light outputted from the laser apparatus;
• a detector configured to detect feed timing at which the target is fed from the target feeder and to provide the light emission trigger generator with a first timing signal indicating the feed timing;
• and
• a timer circuit configured to generate a second timing signal and to provide the light emission trigger generator with the second timing signal, during absence of the first timing signal from the detector,
• wherein the light emission trigger generator generates the light emission trigger signal, based on the first timing signal and the second timing signal.