A video projection system (50) comprises a rotary disc (31) having light guiding devices (35) extending radially thereof and in a helical configuration circumferentially at the disc (31) and corresponding in number to the number of lines to be scanned on a screen (48) the arrangement being such that, as the disc (31) rotates, a light bundle is directed through successive devices (35) which cause the bundle to be scanned on the screen (48).