Virtual Object

There is a concept virtual object that is similarly defined; an object is virtual when forward extensions of real rays converge toward it. In other words, a virtual object point is to which the real rays appear (not actually) to converge (while a real object point is from which real rays emit). This is observed in ray tracing for a multi-lenses system or a diverging lens. For a diverging lens, forward extension of real converging rays toward it will meet the converging point, so the point is a virtual object.