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.

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 an image which is located in the plane of convergence for the light rays that originate from a given object. 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 an eyeball retina (the camera and eye focus 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 if and only if the object is placed further away from the mirror/lens than the focal point and this real image is inverted. As the object approaches the focal point the image is approaching infinity, and when the object passes the focal point the image becomes virtual and is not inverted.

See also

• Virtual image
• Focal plane
• Image plane
• Lens