Method of and system for opto-electronic inspection of a two-dimensional pattern on an object

US4692943A · kind A · utility

Assignee

• Dr. Ludwig Pietzsch GmbH · DE

Inventors

• Ludwig Pietzsch · Karlsruhe, DE
• Knud Overlach · Ettlingen, DE
• Detlef Senger · Ettlingen, DE
• Walter Breunig · Karlsruhe, DE

Key dates

• Filing date: Dec 27, 1984
• Grant date: Sep 8, 1987
• Expiry date: Dec 27, 2004

Classification

• Technology area (CPC G): Physics
• CPC primary: G06T2207/30141
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In a method of opto-electronic inspection of a two-dimensional pattern on an object, especially a printed board, a micro-inspection is carried out by subjecting line-by-line scanned picture elements in pixel-by-pixel fashion to a sequence of picture operations for inspection of dimensions and spacings, and the respective result is compared with the corresponding scanned pixel. At the same time a macro-inspection is carried out by combining the scanned pixels to frames and by respective reduction thereof to a single characteristic picture information, whereupon a comparison is again performed, but this time with the corresponding picture information of a reference picture. In this way it is possible to perform a quick and fully automatic real-time inspection of two-dimensional patterns, for instance printed boards, both for minute and hardly visible defects and for macro-defects.