Real image
Encyclopedia
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 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.
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 the 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 one faces down 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.http://www.grand-illusions.com/acatalog/Mirage.html
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...
, 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
Ray (optics)
In optics, a ray is an idealized narrow beam of light. Rays are used to model the propagation of light through an optical system, by dividing the real light field up into discrete rays that can be computationally propagated through the system by the techniques of ray tracing. This allows even very...
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
Projection screen
A projection screen is an installation consisting of a surface and a support structure used for displaying a projected image for the view of an audience. Projection screens may be permanently installed, as in a movie theater; painted on the wall; or semi-permanent or mobile, as in a conference room...
(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
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
(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.
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 the other side of the lens or mirror plane, is known as a virtual image
Virtual image
In optics, a virtual image is an image in which the outgoing rays from a point on the object always diverge. It will appear to converge in or behind the optical device . A simple example is a flat mirror where the image of oneself is perceived at twice the distance from oneself to the mirror...
.
A real image is exemplified by a science toy/demonstration called "Mirage" which consists of two facing parabolic mirrors: one faces up, the other one faces down with a hole at its center. A real image of an object at the apex
Apex (geometry)
In geometry, an apex is the vertex which is in some sense the highest of the figure to which it belongs.*In an isosceles triangle, the apex is the vertex where the two sides of equal length meet, opposite the unequal third side....
of the lower mirror appears just above the hole in the upper mirror.http://www.grand-illusions.com/acatalog/Mirage.html