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Abstract
The energy and information content carried by an optical beam can
split into two optical paths when the beam transmitted through a
birefringent crystal corresponding in general to two different components:
the ordinary and extraordinary directions. Assuming a uniaxial crystal
with its optic axis oblique to the surface of incidence, the directions of
refraction are distinct. Therefore, an object placed in front of the crystal
when imaged through an optical system results in two shifted images.
Optical polymers and liquid crystals which exhibit birefringence
have been widely used in industrial and research applications as key
materials for various optical devices such as lenses and functional films
for liquid crystal displays (LCDs).
In the first chapter, a general introduction was introduced about the
phenomena of birefringence, speckle photography and liquid crystal
material. After that the previous work that appeared in these fields were
mentioned. Aim of the work had been identified at the end of the chapter.
In the second chapter, the values of birefringence and dispersion
for quartz, calcite crystals and Fortepan photographic plate were
measured by using advanced techniques of speckle photography and two
beam interferometry. The values of birefringence for these samples were
measured and compared with another polarizing method depending on
the intensity of incident and transmitted light from the sample.
Liquid crystal (LC) state is a distinct phase of matter observed
between the crystalline (solid) and isotropic (liquid) states. Liquid
crystals were found to be birefringent, due to their anisotropic nature.
Liquid crystals can be classified into two main categories: thermotropic
and lyotropic liquid crystals. Thermotropic LCs exhibit a phase transition
into the LC phase as temperature is changed, whereas lyotropic LCs
exhibit phase transitions as a function of concentration.
In the third chapter, the values of refractive indices at different
wavelengths and different degrees of temperature were determined using
Abbe refractometer and UV-visible spectrophotometer for new
thermotropic liquid crystals. Also birefringence at different wavelengths
and different degrees of temperature were measured for these
thermotropic liquid crystals by using new speckle photographic
technique.
In the fourth chapter, the values of refractive indices at different
wavelengths and different concentration were determined for new
lyotropic liquid crystals using Abbe refractometer and UV-visible
spectrophotometer. Birefringence at different wavelengths and different
concentrations for these lyotropic liquid crystals were measured by using
Abbe refractometer and the speckle photographic technique.
In the last chapter, a detailed discription of the devices used in
measurements were illustrated followed by conclusions offering the
findings of the entire study.