A method for controlling multiple cameras and their lens tracking a vehicle in flight at a test range. The method uses an electron beam apparatus 1 comprising a primary optical system 10 serving for irradiating the electron beam onto the sample surface and a secondary optical system 30 serving for detecting secondary electrons emanating from said sample surface to form an image of the sample surface. In response to receiving both the processing request and the first key, the processing request and a second key are sent from the ESB server to a second application server. A second insulative layer is formed over the barrier layer. Thus, the host client computer and the slave client computer are enabled to share browsing of the content received from the server.