Browse Prior Art Database

Laser Scan Digitizer Normalizer

IP.com Disclosure Number: IPCOM000039955D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Casparian, MA: AUTHOR [+2]

Abstract

This article describes a method of producing normalized inspection data, derived from a laser scan head, that permits the output signal to represent the pattern under inspection without the variations introduced by the substrate material and differing optical path lengths and laser colors. The objective, from an instrumentation point of view, is to bias out of the output signal those variations that are produced by the material reflectance and the optics, such that a square illumination envelop results. The proposed electric circuits are structured to produce a multivalued digital output signal which feeds both a feedback path and a signal enhancement circuit. The feedback path through the memory circuits assures constant value from the output when scanning a blank sheet.

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Laser Scan Digitizer Normalizer

This article describes a method of producing normalized inspection data, derived from a laser scan head, that permits the output signal to represent the pattern under inspection without the variations introduced by the substrate material and differing optical path lengths and laser colors. The objective, from an instrumentation point of view, is to bias out of the output signal those variations that are produced by the material reflectance and the optics, such that a square illumination envelop results. The proposed electric circuits are structured to produce a multivalued digital output signal which feeds both a feedback path and a signal enhancement circuit. The feedback path through the memory circuits assures constant value from the output when scanning a blank sheet. Each of scan regions is controlled by individual values from the fast random-access memories. This disclosed technique is useful in multiple-wave- length scanning rosters where the illumination scan envelops are not identical.

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