The illuminator is a built-in light source in the base of most microscopes that provides even, high-intensity light at the place of the field aperture. The purpose of the illuminator is to ensure that light can travel through the condenser to the specimen, so that the viewer can see small objects easily without straining the eyes. The level of illumination is intense enough to create a brilliant background for viewing all sorts of microscopic objects that may otherwise be obscured from view. The illuminator can be a steady light source that shines up through the slide, or a pivoted mirror that reflects light from an external light source up through the bottom of the stage. The illuminator can also be calibrated to control various aspects of the level of illumination, and it can even provide more color enhancement. The viewer can control light levels through one or more optical lenses. The illuminator is an essential feature of a microscope, as it enables the viewer to see the specimens internal details.