Paper
17 March 1983 High Speed Pattern Inspection System
Burton D. Figler
Author Affiliations +
Abstract
In many industrial applications, inspection and quality control is required for two-dimensional patterns on flat surfaces. This paper describes a computer controlled pattern inspection system capable of resolutions and positional accuracies in the 1 to 2 mil range. For sample sizes up to 48-inches in length and up to 4-inches in width, total inspection is accomplished within 50-seconds. Inspected patterns are compared, in real time, with a computer stored master pattern. The system is designed to store up to 60 patterns in disk memory and can swap patterns within 10-seconds. During the inspection, the data on the measured pattern is continuously checked against preselected tolerances. Out of tolerance conditions are immediately flagged, permitting the inspection to be terminated and the sample to be rejected. Pattern sensing is performed with a 2048-element CCD silicon detector array. The CCD signals are amplified and thresholded in a high speed AGC amplifier. The analog signals are then digitized in a 6-bit A/D flash converter. Thereafter, signal processing is performed digitally. Illumination is provided by a 300-watt tungsten-halogen linear filament lamp, used in conjunction with a cylindrical lens condenser. Both the illumination and the projected image of the CCD array span a 4-inch field. The illuminator and sensor are mounted on a carriage that rides on a precision air bearing table. A velocity controlled D.C. servo, accurate to 0.01%, is used to drive the carriage along the long axis of the pattern to provide up to 48-inches of coverage at speeds of up to 1-inch per second. A linear glass scale optical encoder reads carriage position to an accuracy of better than 1-mil.
© (1983) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Burton D. Figler "High Speed Pattern Inspection System", Proc. SPIE 0359, Applications of Digital Image Processing IV, (17 March 1983); https://doi.org/10.1117/12.965976
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KEYWORDS
Inspection

Servomechanisms

Computer programming

Lamps

Charge-coupled devices

Electronics

Digital image processing

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