Patent ID: 11927891
Assignee: ASML NETHERLANDS B.V.
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 11:
12. A method comprising:
irradiating an object with acoustic waves,
receiving, at a sensor, at least a portion of the acoustic waves reflected from a target, wherein the senor comprises an optical detector that comprises at least one optically reflective member arranged to receive the at least a portion of the acoustic waves reflected from the target, wherein the at least one optically reflective member is arranged to be mechanically displaced in response to the received acoustic waves;
illuminating with illumination the at least one optically reflective member using at least one radiation source that is also arranged to provide and to direct a reference beam along a radiation beam reference path in the optical detector;
measuring the mechanical displacement of the at least one optically reflective member induced by the received acoustic waves using the illumination, and
deriving characteristics of the target from the measured mechanical displacement.