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Regularities of formation of synthetic optical anisotropy of polymethyl methacrylate for polarimetric application

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General principles of wav plate manufacturing are considered. The possibility of the formation of

synthetic optical anisotropy of polymethyl methacrylate (PMMA) by the method of its uniaxial stretching is

investigated. The most promising is a method for manufacturing waveplates, which includes the stage of controlled

stretching of the polymer material to the required phase shift value, which would generally exclude the stage of

machining the plates. The general orderliness of the molecules in the polymer resulting from stretching (orientation)

leads to the oriented state of the polymer, and, consequently, to the general anisotropy of the physical and optical

properties. In this state, a clearly pronounced uniaxial orientation of polymer chains is observed. As a result, chain

macromolecules, randomly (statistically) oriented in the initial PMMA, acquire orientation under the influence of an

external directed tensile force. The anisotropy of the optical properties of uniaxially stretched PMMA is manifested in

the fact that it has different refractive indices for light polarized parallel to the direction of stretching (orientation) and

in the perpendicular direction (birefringence). The regularities of the formation of the synthetic optical anisotropy of

PMMA have been studied. The dependences of the birefringence values of uniaxially stretched PMMA on the initial

sheet thickness, stretching temperature, and degree of stretching have been measured. It has been shown that the value

of birefringence is directly proportional to the thickness of the initial sheet and the degree of stretching and inversely

proportional to the stretching temperature. The spectral dependence of the birefringence value is measured. Achromatic

and superachromatic waveplates were made from uniaxially stretched PMMA. The spectral characteristics of the phase

shift of the manufactured waveplates are given. The availability of the starting material, the technological simplicity of

the formation of the initial components for waveplates, as well as the possibility of manufacturing waveplates of large

dimensions and high quality, make polymethyl methacrylate with artificially induced anisotropy a promising material

for the manufacture of achromatic and superachromatic waveplates.


Optoelectron. Semicond. Tech. 55, 173-178 (2020)