In
optics, a
virtual image is an image formed when the outgoing
rays from a point on an object always
diverge. The image appears to be located at the point of apparent divergence. Because the rays never really converge, a virtual image cannot be projected onto a screen. In diagrams of optical systems, virtual rays are conventionally represented by dotted lines. Virtual images are located by tracing the real rays that emerge from an optical device (
lens,
mirror, or some combination) backward to a perceived point of origin.