Patent ID: 7230713

Claim:
A method for measuring the gap of a liquid crystal cell comprising the steps of: (a) a step of measuring a reflection intensity S 1 in a cross Nicol state by passing a light with a polarization angle of θ 1 of a polarizer from a light source and introducing the light into a liquid crystal cell prepared as a sample, and passing light reflected from the liquid crystal cell through an analyzer; (b) a step of measuring a reference reflection intensity Ref 1 in a condition where the analyzer is detached, and passing a light with a polarization angle of θ 1 of the polarizer from the light source and introducing the light into a reference; (c) a step of measuring a reflection intensity S 2 in a cross Nicol state by passing a light with a polarization angle of θ 2 of the polarizer from the light source and introducing the light into a liquid crystal cell, and passing light reflected from the liquid crystal cell through the analyzer; (d) a step of measuring a reference reflection intensity Ref 2 in a condition where the analyzer is detached, and passing a light with a polarization angle of θ 2 of the polarizer from the light source and introducing the light into the reference; and (e) a step of calculating a ratio between the measured intensities S 1 ·Ref 2 /S 2 ·Ref 1 ; and (f) comparing the ratio between the measured intensities S 1 ·Ref 2 /S 2 ·Ref 1 with ratios between theoretically determined reflection intensities so that a value of cell gap corresponding to the closest theoretical intensity ratio is determined to be the gap of the liquid crystal cell; (g) storing the gap of the liquid crystal cell in a memory of a data processor.