A lenticular lens
is an array of magnifying lenses, designed so that when viewed from slightly different angles, different images are magnified. The most common example is the lenses used in lenticular printing
, where the technology is used to give an illusion of depth, or to make images that appear to change or move as the image is viewed from different angles.
Lenticular printing is a multi-step process consisting of creating a lenticular image from at least two existing images, and combining it with a lenticular lens. This process can be used to create various frames of animation
(for a motion effect), offsetting the various layers at different increments (for a 3d
effect), or simply to show a set of alternate images which may appear to transform into each other.
Lenticular lenses are sometimes used as corrective lenses
for improving human vision. A bifocal lens
could be considered a simple example.
Lenticular eyeglass lenses have been employed to correct extreme hyperopia (farsightedness), a condition often created by cataract surgery when lens implants are not possible. To limit the great thickness and weight that such high-power lenses would otherwise require, all the power of the lens is concentrated in a small area in the center. In appearance, such a lens is often described as resembling a fried egg: a hemisphere atop a flat surface. The flat surface or "carrier lens" has little or no power and is there merely to fill up the rest of the eyeglass frame and to hold or "carry" the lenticular portion of the lens. This portion is typically 40 mm in diameter but may be smaller, as little as 20 mm, in sufficiently high powers. These lenses are generally used for plus (hyperopic) corrections at about 12 diopters or higher. A similar sort of eyeglass lens is the myodisc, sometimes termed a minus lenticular lens, used for very high negative (myopic) corrections.
Screens with a molded lenticular surface are frequently used with projection television
systems. In this case, the purpose of the lenses is to focus more of the light into a horizontal beam and allow less of the light to escape above and below the plane
of the viewer. In this way, the apparent brightness of the image is increased.
Ordinary front-projection screens can also be described as lenticular. In this case, rather than transparent lenses, the shapes formed are tiny curved reflectors.