Patent ID: 11971663
Assignee: ASML NETHERLANDS B.V.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 9:
10. A lithographic apparatus comprising:
a light source configured to emit a time-varying spectrum of light over a predetermined time window to illuminate a metrology target;
a projection system;
a detection system; and
a metrology apparatus, comprising:
a spectrometer configured to measure a characteristic of the time-varying spectrum of light emitted from the light source over the predetermined time window;
a sensor configured to measure light received from the metrology target and generate metrology signals therefrom; and
a controller configured to:
use the measured characteristic to control the spectral output of the light source prior to interacting with the metrology target and to process the metrology signals,
process the metrology signals based on the measured characteristic,

wherein the processing of the metrology signals further comprises band-filtering the metrology signals, and the band-filtering is adjusted based the measured characteristic, and
wherein the adjusting of the band-filtering is done dynamically to reduce a variation in a center frequency of the time-varying spectrum light.