Abstract: A transparency intended for use in a high intensity light beam projector for stage lighting purposes, comprises a glass substrate (10) having selected areas (11) thereof coated with a multi-layer dielectric coating forming a dichroic color filter. Selective coating is effected either by removing parts of an overall multi-layer coating through a mask, or by applying the multi-layer coating selectively through a mask.

Abstract: A stage lighting lamp unit includes a processor for receiving control data from a remote console. Beam orientation data for the lamp unit is passed to the lamp in the form of the x, y and z co-ordinates of a point in space through which the beam is to pass. The processor divides the required lamp travel into a number of stages dependent on execution duration data sent with the position data, and calculates, for each stage, a new value for pan and tilt angles for the lamp. These values are passed to pan and tilt controlling co-processors which control servo-motors for pan and tilt operation. The lamp unit also incorporates a rotatable shutter for interrupting the lamp beam when required. The shutters of all the lamps in a system can be instructed from the remote console to open and close in synchronism, thereby providing a stroboscopic effect.