Real image

Top: The formation of a real image using a convex lens. Bottom: The formation of a real image using a concave mirror. In both diagrams, f  is the focal point, O  is the object and I  is the image. Solid blue lines indicate light rays. It can be seen that the image is formed by actual light rays and thus can form a visible image on a screen placed at the position of the image.

A convex lens gathers light from different regions of the object onto different regions of the detector or retina, producing a real image. Each region of the detector or retina indicates the light produced by a corresponding region of the object.

In optics, a real image is a representation of an object (source) in which the perceived location is actually a point of convergence of the rays of light that make up the image. If a screen is placed in the plane of a real image the image will generally become visible on the screen. Examples of real images include the image seen on a cinema screen (the source being the projector), the image produced on a detector in the rear of a camera, and the image produced on a human retina (the latter two pass light through an internal convex lens).

In ray diagrams (such as the images on the right), real rays of light are always represented by full, solid lines; perceived or extrapolated rays of light are represented by dashed lines. A real image occurs where rays converge, whereas a virtual image occurs where rays only appear to converge.

Real images can be produced by concave mirrors and converging lenses.

When we look into a convex mirror or see through a concave lens, what we see is not a real image. This image, which appears to be on other side of the lens or mirror plane, is known as a virtual image.

A real image is exemplified by a science toy/demonstration called "Mirage" which consists of two facing parabolic mirrors. One faces up, the other faces down one with a hole at its center. A real image of an object at the apex of the lower mirror appears just above the hole in the upper mirror.[1]

See also

• Virtual image
• Focal plane

• Image plane