This thesis use laser diode, lens, grating, and mirrors to composite the external cavity system to retrieve the thickness of the liquid crystal and its characteristics. This way is different to the traditional way of measure. It has good accuracy on the vertical resolution and the vertical resolution can reach to 0.3£gm. At the same time, it can develop the high quality of horizontal resolution. On the basis of the correlation between the cavity length and the wavelength of the semiconductor laser, the system is capable of developing high horizontal resolution of accurate liquid crystal measurements. The horizontal resolution can reach to 40£gm. Furthermore, by adding bias on liquid crystal through this system, it expanded more understandings on the influences of bias and induced electric field of the electrodes to the tilting angle of the liquid crystal.

In this study, a double-ellipsoid structure is proposed for measurements of optical properties of liquid-crystal displays (LCDs). By using the double-ellipsoid structure, light dispersion and measurement time, which occurs during the measurement of optical properties of LCDs, can be greatly reduced. The system also significantly decreases reflective loss on interface, increasing the accuracy of the measurement. Moreover, by using the conoscopy measured from the proposed structure, light distribution of the dark state along off-axis direction can be analyzed. Based on the analysis, the cell gap and pretilt angle of vertical alignment liquid-crystals (VA-LCs) are evaluated. The proposed structure, which exhibits a fast and high accuracy measurement, is highly promising for future optical measurement of LCDs.