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

Claim 7:
8. A metrology 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 spectrometer configured to measure a characteristic of the time-varying spectrum of light emitted from the light source over the predetermined time window;
a controller configured to use the measured characteristic to condition a spectral output of the light source prior to interacting with the metrology target and to process metrology signals, wherein:
when the spectral output is conditioned the spectral output is band-filtered and the band-filtering is adjusted using the measured characteristic,
the adjusting of the band-filtering is done dynamically to reduce a variation in a center frequency of the time-varying spectrum of light; and

a sensor configured to measure light received from the metrology target and generate the metrology signals therefrom,
wherein the controller is further configured to process the metrology signals based on the measured characteristic.