Maxwell Laboratories, Inc.

John D Hoogerwerf

Richard R Hamm

Michael C Cates

Pulsed light sources, such as a flashlamp or laser, remove coatings from substrates via the ablation method. A photodetector circuit, sensing reflected light from the surface being ablated, provides a feedback signal that indicates the reflected color intensity of the surface being ablated. The boundary between the coatings or substrate surfaces is distinguished by a change in color intensity between an upper coating and an undercoating, e.g., between a topcoat of paint and a primer coat of paint, or between a coating and the substrate surface itself. The color intensity determination thus provides a measure relative to when one coating has been removed and another coating remains. The photodetector circuit is also useful for providing feedback information relative to the quality of a stripped work surface for quality control or other purposes.

Method and system for selective removal of material coating from a

A method for removing material from a structure, comprising the steps of: (1) generating a light beam; (2) irradiating the surface material of a structure with the light beam having an intensity sufficient to ablate the surface material and to cause the surface material to generate spectral emission signals having intensities; (3) scanning the structure with the light beam at a scan speed; (4) monitoring the spectral emissions to detect a selected one of the spectral emission signals having a selected wavelength and generating an electronic output signal representative of the intensity of a selected one of the spectral emission signals in response to detecting the selected one of the spectral emission signals; (5) determining an updated scan speed functionally related to the electronic output signal; and (6) directing the scan speed to be equal to the updated scan speed. A second embodiment determines the updated scan speed based on the intensity of spectral emission signals detected during predetermined intervals while the structure is illuminated by the light source. A third embodiment determines an updated scan speed based on the intensity of spectral emission signals resulting from a laser pulse irradiating the structure when the output of the light beam is approximately at a minimum.

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San Diego, CA, United States of America

John D Hoogerwerf