A gobo is a template that light shines through to project an image onto a surface and it is placed inside or in front of a light source, to control the shape of the emitted light. They are often used with stage lighting instruments to manipulate the shape of the light which is cast over a space or object. A metal gobo with patterned holes allows only the desired shape or pattern of light through, casting a specific pattern of light and shadow into the space.
A glass gobo is an extraordinary way to project colorful images with great detail. Gobos are stencils that selectively block light to create an image. Usually, gobos are made of metal, but glass gobos were created to add color as well as more details.
Though the term “gobo” has come to generally refer to any device which produces patterns of light and shadow, and various pieces of equipment that go before a light (such as a gobo arm or gobo head), in theatrical lighting applications the term more specifically refers to a device placed in ‘the gate’ or at the ‘point of focus’ between the light source and the lenses (or other optics). This placement is important because it allows a pattern with crisp, sharp edges to be projected (for logos, fine detail, architecture, etc.).