Method of Thickness Measurement of Liquid Crystal Cells

The thickness of a liquid crystal (LC) cell is one of the main parameters of liquid crystal devices (LCD). This paper proposes a measurement method based on the multiple-beam interference between the two substrates of the LC cell. The transmitted beam after passing through the LC cell is collected and measured by a fiber optic spectrometer. The interference spectrum data is automatically analyzed through a Matlab program and the thickness of the LC cell is identified. Two LC cell samples with the thicknesses of 4 μm and 10 μm are tested with this method, and the tested results are 3.95 μm and 9.16 μm, respectively. The experimental results show that this proposed method is simple, efficient, and highly accurate.