A cylindrical lens is a

lens A lens is a transmissive optical device that 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

focus Focus (: foci or focuses) may refer to: Arts * Focus or Focus Festival, former name of the Adelaide Fringe arts festival in East Australia Film *Focus (2001 film), ''Focus'' (2001 film), a 2001 film based on the Arthur Miller novel *Focus (2015 ...

es 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, 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.

If a thin cylindrical rod is placed on a ruled white paper with the axis of the rod making an angle θ with the ruled lines, the lines will appear broken and tilted at some angle α as shown in the figure, the Refractive Index of the rod can be given as : Case of Cylindrical 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. The lens and cornea of an eye without astigmatism are nearly spherical, with only a single radius of curvature, and any refractive errors ...

. * 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 ab ...

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

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

and diplopia.

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 allows a wavefront to be recorded and later reconstructed. It is best known as a method of generating three-dimensional images, and has a wide range of other uses, including data storage, microscopy, and interfe ...

. * Doublet cylinder lens system is used in

optical coherence tomography Optical coherence tomography (OCT) is a high-resolution imaging technique with most of its applications in medicine and biology. OCT uses coherent near-infrared light to obtain micrometer-level depth resolved images of biological tissue or oth ...

. * 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