1.06μm / LWIR dual band antireflection coatings were designed and prepared onto ZnSe substrate. Resonance field effects were investigated at the designing stage to improve laser damage threshold of the coatings, and films were prepared onto substrates with different surface quality and properties of the deposited films were investigated. The packing density and mechanical properties of ZnS films were improved by experiment analysis of ZnS prepared by IAD and optimization of the parameters of this technique. The technique properties of the materials dispersive absorption data based on optimized parameters were stable, and the optical property of the deposited films was improved. Films with transmittance of above 96.5% in the 7.7~10.5 μm region and 94% at 1.064 μm and laser damage threshold above 85MW/cm<sup>2</sup> were prepared with such parameters, and the dual band AR coatings passed environmental tests specified by MIL-C-675C. The coated ZnSe windows meet with the demands of electro-optical systems, in which laser and IR works in common aperture, serviced in battlefield environment.
DLC/BP ultra durable LWIR (long wave infrared) protective coatings have been designed and prepared on ZnS (Zinc Sulphide) windows successfully. Both of BP and DLC coatings are deposited by RF-PECVD (radio frequency enhanced plasma chemical vapor deposition) process, but in different chamber. The transmittance, micro-hardness and durability of DLC/BP coatings have been investigated, which are measured by FTIR spectroscopy, micro-hardness tester and simulative harsh environmental test system. The ZnS window outer face coated with DLC/BP coatings and inner face coated with high efficient antireflection coatings is also fabricated. In the band of 8~11.5μm, the measured maximum transmittance is above 93% and the average transmittance is about 89%. The coated ZnS windows meet with the demands of LWIR electro-optics systems workable in battlefield environment.
In this paper, high quality DLC coatings on large area (φ=150 ~ 250mm) infrared elements have been prepared by radio frequency enhanced plasma chemical vapor deposition (RF-PECVD) method. The microstructure has been studied by using Raman spectroscopy and FTIR spectroscopy. These DLC coatings show good uniformity, high infrared transmittance and resistance to harsh environment. The relations between RF power density, the microstructure and properties have been discussed
In present work, Ag-SiO<sub>2</sub> nano-composite coatings with Ag/Si=0.01~0.10(atom ratio) on soda-lime-silicate glasses have been prepared by sol-gel method. The optical absorption (OA) and photoluminescence (PL) spectroscopy of the coatings have been studied. The photoluminescence properties and mechanisms of samples, excited with 228nm and 325nm, have been discussed. The results indicate that the photoluminescence mostly associate with silver, which are in different chemical states. Excited with 228nm, the emission bands centered at about 365nm and 460nm originate from the electron transitions of <sup>1</sup>D<sub>2</sub>→<sup>1</sup>S<sub>0</sub> and <sup>3</sup>D→<sup>1</sup>S<sub>0</sub> in Ag<sup>+</sup> respectively. Excited with 325nm, the emissions bands of 350~500nm and 640~690nm due to the silver clusters (Ag<sub>2</sub><sup>+</sup>, Ag<sub>3</sub><sup>+</sup>, etc.) and silver nanoparticles respectively. The presence of the silver nanoparticles gives a yellow color to the coatings, which show the well-know absorption band at about 400nm results from surface plasmon resonance. The XPS and TEM results show that the heat-treatment temperature, the Ag/Si ratio can influence chemical states of silver and can regulate the size, amount and distribution of silver nanaparticles in the matrix, then influence the optical properties.