New Characterization Technique for Rubbed Polyimide Film for Liquid Crystal Display

Abstract

A new technique is proposed to characterize optical anisotropy of rubbed polyimide film used in liquid crystal displays. The technique consists of measuring the polarization of reflected light in various incident orientations using a combination of a microscope objective, a half-wave plate, and a two-dimensional position-sensitive detector. High spatial resolution without mechanical rotation of the sample is achieved. The performance of this technique was demonstrated by observing a rubbed polyimide film on a glass substrate.

Study of Ultra-Small Optical Anisotropy Profile of Rubbed Polyimide Film by using Transmission Ellipsometry

“…The optical birefringence (Δn =0.011) and the thickness of aligned layer (d=38.8 nm) is comparable to the previously reported values. [6][7][8][9][10][11][12][13][14][15][16] The incident angle (36.9 degrees) is a few degrees off from the incident angle set in the measurement system. This deviation is due to the fact that the measured ellipsometric constants are precise but they are not accurate enough and too many strong correlated parameters are used to get the best fit numbers in the model analysis.…”

“…However, most optical techniques are applied after LC injection since the optical anisotropy of the rubbed alignment layer is too small to be detected using conventional optical techniques [7][8][9]. In order to characterize the optical anisotropy of the rubbed PI surface itself, a polarization sensitive optical technique such as ellipsometry is used [3,6,[10][11][12][13][14][15][16][17]. The frontier work of ellipsometric characterization was reported by Hirosawa.…”

Evaluation of Molecule Orientation on Liquid Surface in Transient State Using by Anisotropic Reflection

“…Fig. 8 Transient optical anisotropy on application film of HPC 50 wt% aqueous solution during drying measured by polarimetry technique consisted by a semiconductor laser and polarization state generator/analyzer and two photodetectors 8,9) . (a) is shown absolute birefringence |Δn′ | and orientation angle α′.…”

Wide-Viewing Observation and High-Spatial Resolution Characterization of Rubbed Polyimide Film for Liquid Crystal Display

“…But, due to the symmetry of the distortion of the circular polarization, we can observe the change of the polarization of the reflected light for rubbed PI film from all incident orientations at the same time.Compared with the incidence of the linear polarized light to the objective, this enables to decrease the measurement time [4]. Moreover, the incidence of circular polarization enhances the sensitivity of the measurement due to the incidence of the polarization w i t h both p component and s-component to the sample.…”