Fine droplets with a narrow size distribution are generated from a liquid stream, when an ultrasonic or pneumatic spraying device is used. The liquid containing the sol-gel precursors breaks into droplets that are directed at a substrate, in some cases using a DC voltage for electrospraying. The process of spray deposition encompasses several techniques and many variables. By adjusting the variables, high quality optical films can be achieved. The advantages and disadvantages of these processes are discussed in detail.