Lenses

Materials

Illustration

Property and Application

Plano-convex

BK7
Fused Silica
CaF₂

Positive focus length. Most suitable where one conjugate is more than five times the other, e.g. in sensor application or for use with near collimated light.

Double-convex

BK7
Fused Silica
CaF₂

Most suitable where the conjugates are on opposite sides of the lenses and the ratio of the distances is less than 5:1, e.g. as simple image relay components.

Plano-concave

Fused Silica

Negative lens with the form most suitable where one conjugates is more than five times the other, e.g. producing divergent light from a collimated input beam.

Double-concave

BK7
Fused Silica
CaF

Negative lens with the form most suited to producing diverging light or a virtual image, where the input light is converging.

Meniscus

Positive

BK7

These lenses may be used to increase the numerical aperture of a positive lens assembly, without an undue increase in the aberrations.

Negative

BK7

The best lens form where one conjugates is relatively far from the lens or where both conjugates are the same size of the lens.

Cylindical

BK7

Fused Silica

Used to provide focusing power in one section only. For illumination or detection of light from line sources. Also used to anamorphic compression of beams and images.