diverging lens

The distance found is the (negative) focal length of the diverging lens.

It consists of a group of lenses which together act as a single diverging lens.

The image produced by a diverging lens is however frequently virtual and consequently the focal length does not seem easy to determine.

In principle, everything applies to diverging lenses just as well as to converging lenses.

The focal length f is positive for converging lenses, and negative for diverging lenses.

Converging lenses have positive optical power, while diverging lenses have negative power.

Light from a laser is expanded by a diverging lens (not shown), then is collimated into a parallel beam.

When we look through a diverging lens (at least one concave surface) or look into a convex mirror, what we see is a virtual image.

Since Abbe numbers are positive, one of the focal lengths must be negative, i.e., a diverging lens, for the condition to be met.

But like a diverging lens, the flow focused gravity away from her, while equally ferocious forces kept the walls from crushing in at only fractionally less than the speed of light.

If the lens is biconcave or plano-concave, a collimated beam of light passing through the lens is diverged (spread); the lens is thus called a negative or diverging lens.

It can be corrected by making the surfaces non-spherical or 'aspheric' but the more usual cure is to share the refraction over more surfaces and to balance the opposing defects of converging and diverging lenses.

For a diverging lens (for example a concave lens), the focal length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens.

Telephoto is designated because the longer focal length supplied by the negative diverging lens is longer than the overall lens assembly (the negative diverging lens acting as the "telephoto group").

For presbyopia and hyperopia, a converging lens provides the extra curvature necessary to bring the near point closer to the eye while for myopia a diverging lens provides the curvature necessary to send the far point to infinity.

The Barlow lens, named after Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components after it is in the system.

The optical power of corrective lenses is measured in diopters, a value equal to the reciprocal of the focal length measured in meters; with a positive focal length corresponding to a converging lens and a negative focal length corresponding to a diverging lens.

One special application is to determine the focal length of a diverging lens: A light source is placed at twice the focal length of a converging lens on one side and a screen at the same distance on the other side so that the image of the light source is the sharpest possible.

When this is achieved, the screen is replaced with a mirror and the diverging lens is inserted between the converging lens and the light source at such a distance to the mirror that the light returning through the diverging and converging lenses produces a sharp image on top of the luminous object.