Test of reflective MTN liquid crystal cell for the LCOS microdisplay by guided wave method

In order to confirm the function of MTN model in our LCOS microdisplay device, we made the MTN test cell, in which low substrate is also glass instead of silicon. Since a standard commercial-like liquid crystal cell with low index glass( with an index close to 1.52) plate is to be investigated by a guided model technique to unravel the director profile through the cell, the low index improved fully leaky guided model(IFLGM) technique are chosen. At higher applied voltages (in our study U≥5.0 V(rms), the voltage-dependent reflectance can not be distinguished. In this range of the applied voltage, the electric fields create tiny difference in the distribution of the director only near the substrates and waveguide signals are just sensitive to this difference. Fitting the data in reflection by using the modeling-program based upon multilayer optical theory together with continuum theory gives the information about the pre-tilt and twist of the director as well as the parameters of different optical layers. We found that the pre-tilt angle on the top substrate is smaller 1° than that on the bottom in the best fit, this suggests that the ITO and the aluminum coatings have different effects on the alignment layers.