Image analysis method to study electro-optic parameters of nematogens

Abstract

This paper demonstrated the image analysis technique for the investigation of electro-optic behaviour of homogeneously aligned nematic liquid crystals p-n alkyl benzoic acids (nBA) where n = 5 and 6 under the application of direct current (DC) electric field. Textures of the liquid crystals in the mesophase region of particular temperature were recorded in three monochromatic image planes at the wavelengths of 635 (red), 530 (green) and 475 nm (blue) as a function of applied DC voltage. Electro-optic properties such as transmittance, birefringence, phase retardation and contrast ratio were measured by analysing the optical intensities of the recorded textures using MATLAB software. The changes in the textural features and formation of new textures as a function of voltage provided information for better understanding of the electro-optic characteristics of liquid crystals. Results of this study were compared with the data of the other standard techniques: laser source (633 nm) experiment and United Detector Technology (UDT) sensor of model UV- 35P silicon photo diode which uses white light as source and filters the wavelengths using three colour filters of wavelengths 635, 530 and 475nm.

Keywords:

• electro-optic
• image analysis
• nematogens
• textures

Funding

The authors gratefully acknowledge UGC DRS LEVEL III program [No.F.530/1/DRS/2009 (SAP-I)], dated 9 February 2009, and DST FIST program [No. DST/FST/PSI – 002/2011], dated 20 December 2011, New Delhi, and to the department of Physics, ANU, for providing financial assistance.