Patent ID: 11860036
Assignee: CYMER, LLC
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 9:
10. A method of monitoring a calibration parameter of an etalon during use of the etalon, the method comprising:
receiving data from a detector positioned to sense an interference pattern produced by an etalon that receives a light beam, wherein the interference pattern comprises a plurality of fringes based on the received light beam, and the data comprises first spatial information related to a first fringe of the plurality of fringes and second spatial information related to a second fringe of the plurality of fringes;
accessing a calibration parameter associated with the etalon, the calibration parameter having a pre-set default value;
determining a first wavelength value of the received light beam based on the first spatial information related to the first fringe and an initial value of the calibration parameter;
determining a second wavelength value of the received light beam based on the second spatial information related to the second fringe and the initial value of the calibration parameter;
comparing the first wavelength value and the second wavelength value to determine a measurement error value; and
determining, during use of the etalon, whether to adjust the pre-set default value of the calibration parameter based on the measurement error value.