Terahertz (THz) radiation is located in the spectral region ~0.1-10 THz (~3 mm - 30 m, 3 cm-1 - 300 cm-1) between the microwave and mid infrared range of the electromagnetic spectrum. In comparison with visible or infrared waves, THz radiation can penetrate into organic materials such as skin, plastics, cloth, or paper products. Because of low photon energy involved, it does not cause any damage associated with ionizing radiation ( e.g. X-rays). THz waves do not penetrate into metals. These properties can be used in process (e.g. drugs manufacturing) and quality control as well as in THz imaging. It is also of great current interest for such applications as safety control, packaging inspection, semiconductor characterization, chemical composition analysis, and biomedical investigations, with great promise for spectroscopy, defense imaging, and security applications. Traditionally for THz applications we use High Resistivity Float Zone Silicon (HRFZ-Si) as it is the most investigated substance for operating within this range and has a good transmission performance. In parallel with this material we have been investigating other materials which also can be utilized in THz range. Below you can see transmission spectra and other characteristics of materials we use for THz optics production. Measurements in THz region were made at ABB FTIR spectrometer Bomem DA3 and Bruker IFS 125HR (measure of inaccuracy is 2-3% below 100 m and 4-5% over 100 m). Measurements in near infrared range were made at Perkin Elmer Lambda- 9 (measure of inaccuracy < 0.5%). SP中紅外光譜儀