A gobo (graphical optical blackout) is a mask (originally made of metal, today also often made of glass) that is plugged into a spotlight or projector to display logos, patterns, texts or images on stage or for advertising purposes. The display is similar to a slide projection or with simpler devices as a shadow projection. Wikipedia.de
A gobo is a motif mask/light mask made of glass or metal that is used in projectors to project individual or standard motifs. Gobos have the advantage that they are heat-resistant and can therefore be used permanently in high-performance projectors such as moving heads and profilers.
Glass gobos are made of heat-resistant borosilicate glass with an aluminium coating (b/w) or dichro coating (coloured). Coloured glass gobos are manufactured in a sandwich construction, whereby the individual colours/layers are bonded with heat-resistant silicone. Gobos can be produced with a laser or a photochemical process (&etching process).