TEMPERATURE-DEPENDENCE OF THE EMITTANCE OF LIF AND LINBO3 IN THE NEAR-INFRARED SPECTRA

This study investigates the temperature dependence of the normal emitt ance in 3-5, 5, 10.6 and 8-12 mu m spectral ranee for LiNbO3 and LiF r ods with both crystal and polycrystalline structures. According to the results, the normal emittance in the near-infrared spectra increases with increasing wavelength. The normal emittances at 10.6 and 8-12 mu m are not only invariant with temperature, but also exceed 0.9. When t he temperature increases. the normal emittances at 3-5 and 5 mu m for the LiF single-crystal rod continuously increase regardless of the pha se change from the solid state to the liquid state. Before the tempera ture reaches the Curie point, the normal emittances at 3-5 and 5 mu m for the LiNbO3 single-crystal I od increase with increasing temperatur e. The normal emittances at 3-5 and 5 mu m then decrease as the temper ature further increases. A significant decrease in the normal emittanc e at 3-5 and 5 mu m occurs when the emission is only from the melt. In addition. the magnitudes of the normal emittance at 3-5 and 5 mu m ar e enhanced by the scattering effect due to the porous structure of the solid.