Product Manual：

       HDPE is a light elastic crystal material. It can be heated to 110°C and also cooled to -45 to -120°C. PE has excellent dielectric properties, corrosion resistance and radiation resistance. At 23°C, its density is 0.91-0.925g/cm ³, the tension current limit is 8-13 mpa, the elastic modulus is 118-350 mpa, and the refractive index is approximately 1.54 over a wide spectral range. Usually, HDPE is also used as a component material. In addition to being used as thick lenses and window mirrors, thin HDPE can also be employed as THZ polarizers.
        It should be noted that the THz transmission of HDPE is not dependent on temperature, thus allowing the use of HDPE Windows in low-temperature thermostats. Its refractive index temperature coefficient is 6.2×10-4 K ⁻ ¹ (ranging from 8 to 120 K).

       Teflon is a white solid at room temperature with a density of approximately 2.2 g/cm ³. Its melting point is 327°C, but its properties remain at a useful level within a wide temperature range of -73°C to 204°C. The refractive index is 1.43 over a wide wavelength range.
       Due to its good transmissibility in the range of 1-7μm, Teflon films are used to manufacture infrared or terahertz polarizers. The cost of these polarizers is lower than that of crystal polarizers, which is conducive to their extensive application in IR sensors that use polarized radiation.