What is a gobo?

Glass gobos are made from transparent glass with a partial mirror coating to block the light and produce "black" areas in the projected image. This eliminates any need for bridging, since the glass itself is the support, and allows more intricate images to be produced. Glass gobos can also include colored areas (much like stained glass windows), whether by multiple layers of dichroic glass (one for each color) glued on aluminum or chrome coated black and white gobo or by newer technologies that allow the thickness of the dichroic coating (and therefore the color) to be varied in a controlled way on a single piece of glass, making it possible to turn a color photo into a glass gobo.