Two-dimension phase-retardation distribution inspections for flexible displays by using full-field liquid-crystal modulating common-path interferometry

摘要

For flexible displays in manufacture, the full-field residual stress inspection for films deposited on flexible substrates is an important issue. According to the literature, the material phase retardation is related to its residual stress. This study proposes a novel method of the fast full-field phase-retardation distribution inspection with a flat large-area twisted nematic liquid crystal modulator based on a white light source by using a common-path interferometry. To fast inspect two-dimension (2D) phase-retardation distribution, a tensile testing machine is utilized to provide flexible substrates with tensional forces to enhance the residual stresses for measuring phase retardations in the tensional force direction. Accordingly, a 2D phase-retardation distribution concerning a 125-dpi line-pattern poly(ethylene terephthalate)/indium tin oxide substrate is inspected and analyzed by using a full-field flat liquid-crystal modulating common-path interferometry. 2D phase-retardation distribution inspection results depicted on flexible displays help a designer or maker of flexible displays design useful and comfortable products.