Today, the optical imaging systems can be disturbed by laser attacks with different powers and wavelengths. Hence, it is necessary to utilize optical filters in order to defend against these attacks. The filters for protecting from laser radiation are fallen into two categories of band pass and nonlinear optical materials. The nonlinear optical materials, compared to the band pass filters, have several advantages. For instance, transmission through a wide range of electromagnetic spectrum, flexibility in design and low cost of manufacture. The purpose of this project is to fabricate a specific filter to reduce the intensity of laser radiation with wavelength of 532 nm and protect human eye from this radiation. The filter must be designed to have low intensity limit threshold and be able to reduce the intensity in 1-100 mW/cm2. Among the organic and inorganic materials, copper phthalocyanines, zinc tetraphenyl porphyrin and silver nanoparticles were chosen, because of low response threshold and satisfactory transmission in visible light. Due to limitations in fabrication of filters by some techniques such as glass melting or adding limiters, polymers were introduced as the host material. The polymeric limiter sample was prepared by two methods, first by solving the limiter material in Granule, second by polymerization process. In the first technique hot press and spin coating methods were used for fabrication of the samples, but the second technique didn’t need the finishing step after polymerization. Finally, the optimum sample was produced by polymerization. 3 mm thick sample was prepared with 0.003 weight percent of zinc tetraphenyl porphyrin and 0.005 weight percent of silver nanoparticles. This sample had the limit threshold of ~ 9 mW/cm2 where the input intensity was 100 mW/cm2. Since the sample had suitable intensity reduction and ~60% transmission in visible spectrum, it was known as the final limiter sample. The limitation test was done by a laser with 532 nm wavelength. Light transmission was measured by spectrophotometer equipment.
