One of the key elements of Flat Panel Display industry is the RGB color filter array. Such arrays are manufactured on glass and used to filter the color information present on the image of the display. Many non-contact measurements on the surface of the glass are needed: filter height characterization, photospacer characterization and defect analysis. Sensofar's Plu optical sensors are able to perform measures on the RGB color filter array in manual, semiautomatic and totally automatic modes. For manual and semiautomatic measurements, the SensoMAP software is used for analysis, while for completely automatic working, the system is equipped with SensoPRO.

Photo-spacers are used to align and separate the RGB color filter glass and the light modulation device (LCD, TFT...). With the SensoMAP or SensoPRO software it is possible to characterize the XY position, presence or absence, height and diameter of each photo-spacer. For the photo-spacer recognition, an advanced analysis and characterization of surface based on threshold and 3D binarization is used to isolate each one of the bumps from the rest of the surface. In comparison to single point scanning profilers (like chromatic confocal, triangulation, or AFM), Confocal and Interferential Optical sensors profilers are based on imaging technology. Measurements are performed in few seconds for all pixels of the CCD camera.

High and low magnification optics are used to identify and subsequently measure defects on the surface of the RGB color filter array. During the manufacturing process, a 2D imaging system inspects the surface at high speed looking for defects. Such defects (called MURA) can lower the transmission of the light, and even make the filter not to work properly. The addition of a 3D non-contact profiler after 2D inspection gives the information about the shape of the defect. Appropriate 3D information on height, area and volume of a defect can be used assess whether this is affecting the overall performance of the filter.