Two new measurement methods for determining TN structure

P‐25: An Accurate Spectral Method for Measuring Twist Angle of Twisted Cells with Rubbed and Grooved Surfaces

“…There are noticeable regular deviations of experimental points, which may be attributed to the out-of-plane deformations of the liquid crystal by the grating and corresponding reduction of its birefringence. Dependence of the LC twist angle on its thickness ( fig.8) even more closely follows formula (8). On the other hand, these facts show that spectral method is capable of twist angle determination in very diverse conditions.…”

“…Dependence of the LC twist angle on its thickness (fig. 8) even more closely follows formula (8). On the other hand, these facts show that spectral method is capable of twist angle determination in very diverse conditions.…”

“…Recently, new optical method based on spectral analysis [10] has been proposed. In spite of its advantage compared to the previous ones [7,8,9] it is not capable of measuring twist angle with high accuracy when only the points of minima in the short wavelength region of the spectral curves are considered. More over the preferable thickness of the LC layers in the modern displays is 4 -6 µm.…”

“…There are several methods for measuring twist angle in TN cells [7,8,9]. All of them use monochromatic light and determine the desired angle either by compensators [8,9] or investigate the state of polarization of the transmitted light [9]. Recently, new optical method based on spectral analysis [10] has been proposed.…”

Measurement of reflective liquid crystal displays

“…However, all the previously reported methods for cell gap measurements are meant for transmissive cells. [6][7][8][9][10][11][12][13] These methods require the incident light to pass through the test cell and then the transmitted light is analyzed. They are not directly applicable to the measurement of reflective LC cells.…”