Optical properties of alkali halide crystals

The results of measuring the transparency bands in a wide wavelength range - from UV to 3000 μm for crystals of sodium chloride (NaCl), potassium chloride (KCl), iodine bromide (KBr) and rubidium iodide (RbI) are presented. It was shown that, along with well-known data on the transparency of these crystals in the UV and IR ranges, they have a transmission zone in the THz range in the region of 1000 μm.