In recent display manufacturing processes, real-time full inspection has emerged as an essential factor for improving production yield. Conventional optical metrology sensors based on single-point measurements acquire profile data through mechanical scanning; however, they suffer from limitations such as measurement blind spots, reduced mechanical durability, and synchronization issues in measurement signals. To address these challenges, hyperspectral-based sensors have been introduced. Nevertheless, such sensors are typically limited to continuous linear measurements and face difficulties in performing synchronized multichannel measurements at multiple spatially distributed locations.
In this study, we propose a hyperspectral-based thickness measurement sensor composed of multiple independent optical fiber channels. The proposed system consists of multiple fiber-based probes connected to a single-mode optical fiber coupler. Optical signals acquired independently from each measurement point through the individual probes are simultaneously spectrally resolved within a hyperspectral module with high wavelength resolution and captured in a single acquisition using a two-dimensional image sensor. Notably, the proposed technique enables simultaneous measurements at multiple locations without the need for additional synchronization devices and allows flexible probe placement without spatial constraints, even for curved display panels or physically separated measurement points.
The proposed technology is expected to be applicable not only to thickness measurements of substrates and protective layers in large-area flexible display manufacturing processes but also to extended applications such as packaging or welding condition inspection in advanced semiconductor and secondary battery manufacturing processes.
