Photo-acoustic device and method for non-contact measurement of thin layers
AssigneeNovelis Inc.
InventorsHEINRICH PRINZHORN, STEFAN ERDMANN, THOMAS WUTTKE, ANDREAS BAUER, BERND ABEL, ALES CHARVAT
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Abstract
A measuring device for non-mechanical-contact measurement of a layer, the measuring device including a light source operative to generate a pulse adapted to interact with the layer so as to generate a thermal wave in a gas medium present adjacent the layer. The thermal wave causes an acoustic signal to be generated. The measuring device further includes a detector adapted to detect a first signal responsive to the acoustic signal, the detector not being in mechanical contact with the layer. The first signal is representative of the measured layer.
Claims21
1-20. (canceled)
An apparatus, comprising:
- a measurement head positionable opposite a gas medium from a moving layer for measuring the moving layer, the measurement head comprising:
- an acoustic detector spaced apart from the moving layer;
- and
- a light exit port spaced apart from the moving layer, wherein the light exit port is optically couplable to a light source to convey an optical pulse through the gas medium and towards the moving layer to generate a thermal wave in the gas medium adjacent the moving layer that is sufficient to generate an acoustic signal detectable by the acoustic detector;
- wherein the light exit port is rigidly fixed to the measurement head, and wherein the acoustic detector is rigidly fixed to the measurement head at a distance from the light exit port.
A non-mechanical-contacting measurement method, comprising:
- positioning a light exit port opposite a gas medium from a moving layer, wherein the light exit port is rigidly fixed to a measurement head, wherein positioning the light exit port comprises positioning an acoustic detector opposite the gas medium from the moving layer, and wherein the acoustic detector is rigidly fixed to the measurement head;
- outputting an optical pulse towards the moving layer from the light exit port, wherein outputting the optical pulse comprises generating a light beam at a light source optically coupled to the light exit port, wherein outputting the optical pulse towards the moving layer results in generation of a thermal wave in the gas medium adjacent the moving layer, and wherein generation of the thermal wave results in generation of an acoustic signal;
- receiving the acoustic signal at the acoustic detector;
- and
- processing the received acoustic signal by a signal processor operatively coupled to the acoustic detector.
A method, comprising:
- generating a light beam at an optical source;
- conveying the light beam to a light exit port;
- outputting the light beam from the light exit port as an optical pulse;
- receiving an acoustic signal at an acoustic detector in response to outputting the light beam, wherein the acoustic signal is a result of a thermal wave generated by the optical pulse interacting with a moving layer;
- conveying an electrical signal associated with the acoustic signal to a signal processor;
- processing the electrical signal to determine a measurement of the moving layer;
- and
- moving the light exit port, wherein movement of the light exit port comprises moving the acoustic detector such that a relative distance between the light exit port and the acoustic detector is not influenced by moving the light exit port.
Dependencies are inferred from the claim text.