Comparative study of Light-Section Microscopy and Confocal Microscopy in the Visual Inspection of a Transparent-Layered Product

Abstract

This paper describes comparative study of the light-section method and confocal microscopy in the visual inspection of a LCD. Confocal microscopy with coaxial lighting gives a bright-field image and is often affected by an interference pattern appearing in a gap surrounding a foreign particle between the layers of the LCD. Also, scratches or dust on the surface of the LCD obstruct observation of the foreign particle by occluding the particle image. The light-section method gives a dark-field image and dose not produce any obstructive interference pattern. This method was robust for the scratches and dusts on the surface and was successful in detecting the foreign particles included in the LCD panels in wide field-of-view configuration using plane illumination.