Lenses

Spherical lenses, also known as singlets, are transparent optical components consisting of one or more pieces of optical glass with surfaces so curved that they serve to converge or diverge the transmitted rays from an object, thus forming a real or virtual image of that object.

There are seven main spherical lens forms or shapes that determine the imaging characteristics of the lenses. They are plano-convex, plano-concave, convex-convex, concave-concave, meniscus, aspheric, and ball.

Plano-convex lenses have a positive focal length which makes them ideal for collecting and focusing light for many imaging applications. Plano-concave lenses have a negative focal length and are used for image reduction or to spread light. Convex-convex lenses have a positive focal length and are useful for 1:1 imaging and in multi-element systems and it’s also known as biconvex or equiconvex.

Concave-concave lenses have negative focal length, and are used for image reduction and to spread light and it’s also known as biconcave or equiconcave.

Meniscus lenses can increase the numerical aperture of a positive lens assembly, without an undue increase in the aberrations. Aspheric lenses compensate for spherical aberration and are used primarily for their light gathering ability. Ball lenses are used to provide short focal lengths for use with collimated light. They are often used in fiber coupling applications. The above seven are the most common types, meanwhile there are also other styles of spherical lenses available.