Liquid Crystal Displays

However, manufacturing LCDs is a complex process, involving numerous deposition stages to lay down the active substrates and the color filters on front and rear glass plates. In most cases, 4-6 displays are produced on the same glass plate.

The ability to detect even the slightest flaw in the plate or in the deposited layers is vital in the quality control of LCDs and in ensuring trouble-free operation.

Microscopy is a key tool in the examination of LCD screens as techniques such as brightfield, differential interference contrast and interferometry provide the means to produce the high contrast images needed to spot small imperfections in the deposition layers, detect minute scratches on the glass screens and check the integrity of color filters.

Digital imaging technology enables record keeping and creates an audit trail for QC purposes.

Key techniques for QC in LCD manufacturing include: brightfield illumination; darkfield illumination; Nomarski DIC; diascopic illumination; episcopic illumination; digital imaging.