Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1991-12-24
1993-03-16
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
367135, 21912162, G01J 132
Patent
active
051947234
ABSTRACT:
The present invention provides an automated system and method for removing one or more layers of a material from a substrate. The system and method include irradiating a structure comprising at least one layer of material formed on a substrate with a light beam having an intensity sufficient to ablate the materials in order to expose selected regions of the substrate, where the ablated material generates photoacoustic signature signals; scanning the structure with the light beam along a predetermined path at a scan speed; detecting the photoacoustic signature signals; determining an updated scan speed functionally related to the detected photoacoustic signals; and directing the scan speed to be equal to the updated scan speed. Another embodiment exposes a selected layer of a multilayered structure in a process which includes irradiating the surface of multilayered structure at a first location with a light beam having sufficient intensity to ablate the irradiated layer and generate photoacoustic pressure wave signals; detecting the photoacoustic pressure wave signals generated at the irradiated surface; comparing representations of the photoacoustic pressure wave signals with a reference value corresponding to a photoacoustic signature signal of a layer of the structure selected to be exposed; and directing the light source to scan the surface of the structure at a scan speed functionally related to the difference between the photoacoustic pressure wave signals and the reference value.
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Cates Michael C.
Hamm Richard R.
Le Que T.
Maxwell Laboratories Inc.
Nelms David C.
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