Some peculiarities of designing the optical scheme of tellurium dioxide crystalline cell based acousto-optical spectrometer for the Mexican Large Millimeter Telescope

摘要

The main features of arranging the polarization control in optical scheme of a 1000-channel acousto-optical spectrometer for the needs of radio-astronomy are analyzed. To realize a high-resolution spectrum analysis rather specific acousto-optical cell has to be exploited. For this cell a tellurium dioxide single-crystal oriented along the [001]- and [110]-axes has been chosen. Due to an extremely high anisotropy of this crystal, the efficiency of light scattering depends essentially on the ellipticity of the incident light polarization and increases when the state of polarization reaches the eigen-state of elliptic polarization, which is determined by the incidence angle, light wavelength, and accuracy of the cell's crystallographic orientation. This is why we analyze some peculiarities of designing the beam-shaping scheme, which includes tunable light polarizers and a multi-prism beam expander and has to provide the needed pre-assigned states of light polarization on the inputting aperture of acousto-optical cell.