A cylindrical lens is a

lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements ...

which focuses light into a line instead of a point, as a spherical lens would. The curved face or faces of a cylindrical lens are sections of a

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an ...

, and focus the image passing through it into a line parallel to intersection of the surface of the lens and a plane tangent to it along the cylinder's axis. The lens converges or diverges the image in the direction perpendicular to this line, and leaves it unaltered in the direction parallel to its cylinder's axis (in the tangent plane). A toric lens combines the effect of a cylindrical lens with that of an ordinary spherical lens.

Uses

Uses in optometry

* Cylindrical lenses are prescribed to correct

astigmatism Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at n ...

. * Cross cylinder, which is a combination of two cylindrical lenses with equal strength and opposite power, is used in subjective refraction to diagnose astigmatism, and assess the strength and axis of the astigmatic power etc. *

Maddox rod The Maddox rod test can be used to subjectively detect and measure a latent, manifest, horizontal or vertical strabismus for near and distance. The test is based on the principle of diplopic projection. Dissociation of the deviation is brought abo ...

s, made up of cylindrical lenses arranged in parallel, are used to detect

strabismus Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. The eye that is focused on an object can alternate. The condition may be present occasionally or constantly. If present during a ...

and

diplopia Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...

Other uses

* In a light sheet microscope, a cylindrical lens is placed in front of the illumination objective to create the light sheet used for imaging. * Cylindrical lenses are used in optical spectrometers. * Cylindrical lenses are used in

holography Holography is a technique that enables a wavefront to be recorded and later re-constructed. Holography is best known as a method of generating real three-dimensional images, but it also has a wide range of other applications. In principle, i ...

. * Doublet cylinder lens system is used in

optical coherence tomography Optical coherence tomography (OCT) is an imaging technique that uses low-coherence light to capture micrometer-resolution, two- and three-dimensional images from within optical scattering media (e.g., biological tissue). It is used for medica ...

. * Cylinder lenses are also used in many laser applications. A cylindrical lens can be used to create a laser line. A doublet cylinder lens is used to make laser sheets and circularize elliptical beams from laser diodes.

References

Other Sources

*Jacobs, Donald H. Fundamentals of Optical Engineering. MC Graw-Hill Book Co., 1943.

External links