Method of measure the thickness of liquid crystal layer using phase plate

The measurement of thickness of the liquid crystal layer has been done using the optical interference method with spectrophotometer up to now. But it took more than one minute to measure the thickness, and in-line measurement was impossible. So, in this paper, the measuring method of the thickness of the liquid crystal layer that it is possible to measure the thickness at high speed for about one second is proposed, and it is reported about the principle. And we report the comparison experimental results with this method and conventional method.