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Both the optical and physical properties of thin film optical interference coatings depend upon the microstructure of the deposited films. This microstructure is strongly columnar with voids between the columns. Computer simulations of the film growth process indicate that the two most important factors responsible for this columnar growth are a limited mobility of the condensing molecules and self-shadowing by molecules already deposited. During the vacuum deposition of thin films, the microstructure can be influenced by many parameters, such as substrate temperature and vacuum pressure. By controlling these parameters and introducing additional ones, thin film coatings can be improved. In this research, ultraviolet irradiation and ion bombardment were examined as additional parameters. Past studies have shown that post-deposition ultraviolet irradiation can be used to relieve stress and reduce absorption in the far ultraviolet of silicon dioxide films. Ion bombardment has been used to reduce stress, improve packing density, and increase resistance to moisture penetration. Three refractory oxide materials commonly used in thin film coatings were studied; they are silicon dioxide, titanium dioxide, and zirconium dioxide. Both single-layer films and narrowband filters made of these materials were examined. A 1000-watt mercury-xenon lamp was used to provide ultraviolet irradiation. An inverted magnetron ion source was used to produce argon and oxygen ions. Ultraviolet irradiation was found to reduce the absorption and slightly increase the index of refraction in zirconium oxide films. X-ray diffraction analysis revealed that ultraviolet irradiation caused titanium oxide films to become more amorphous; their absorption in the ultraviolet was slightly reduced. No changes were noted in film durability. Ion bombardment enhanced the tetragonal (lll) peak of zirconium oxide but increased the absorption of both zirconium oxide and titanium oxide films. The titanium oxide films were found to become amorphous with even slight ion bombardment. Little effect was noted in silicon oxide films.

Sol-gel derived silica coatings were deposited on soda-lime-silica by dip-coating. An absorbing metallic layer was sputtered onto the surface of the gel to couple near-infrared radiation from a Nd:YAG laser into the transparent coating. Laser energy was utilized to heat the ceramic coating on a substrate which has a lower glass transition temperature than the coating. Scanning the sample across the beam's path resulted in the formation of a 50 mum wide channel. The characteristics of a channel were altered by varying laser power, sol-gel coating thickness, and scanning speeds. Profilometry and SEM analysis verified that the coating can be heated to high temperatures without damaging the substrate.

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