Preparation and properties of polycarbonate near-infrared absorption filter

A new near-infrared (NIR) absorption filter with good optical and mechanical properties was prepared by injection molding method. It was made by NIR-dyes and polycarbonate. This NIR absorption filter can be applied on light apparatus for night vision imaging system (NVIS) compatible lighting. The optical performance of the filter was studied. The filter material offers sufficient transmittance in the visible spectrum along with excellent extinction in the NIR region. The results also showed there was a good linear relationship between its absorbance and NIR-dye dosage. This means that the optical property of the filter can be easily controlled by changing the amount of NIR-dyes. A NIR absorption filter with optimal dye dosage was prepared. The filter has a transmittance not higher than 0.15% in the NIR region in the wavelength range of 660 -930 nm ; a 16% value of transmittance in the wavelength range of 400 - 630 nm. The filter is excellent in environmental stability that after being left to stand in the air atmosphere at temperature of 85°C and exposed to light condition at 1120 W/m ² for 200 h,the filter can maintain its spectral property in the said range. Its bending strength is 107 MPa,shock strength is 54.4 kJ/m ². Therefore the filter can stand strong mechanical impact in the actual application environment.