A lens focuses or scatters light by refraction, and unlike a prism with the principle of refraction without focusing, the lens focuses light to form an image. Generally, lenses are made of glass or plastic, but there are also liquid lenses using the principle of human eye focusing mechanism. Glass lenses are manufactured to the desired shape through grounding and polishing, while plastic lenses are made by molding.
Simple lenses are basically classified in to eight types according to the curvature of the two optical surfaces.
Converging Lenses
- Convex Lens
- Biconvex lens
- Plano-convex lens
- Positive meniscus
Diverging Lenses
- Concave lens
- Biconcave lens
- Plano-concave lens
- Negative meniscus
Combined lens generally refers to a lens made by combining two or more lenses, such as a convex lens that collects light and a concave lens that emits light. This combined lens reduces chromatic aberration such as image distortion and light streaks, which can't be reduced when only one lens is used.
Lens types include spherical lens, cylindrical lens, infrared optics, ball lenses, array lenses, and many other optical lenses in the industry are configured.
Combined lens generally refers to a lens made by combining two or more lenses, such as a convex lens that collects light and a concave lens that emits light. This combined lens reduces chromatic aberration such as image distortion and light streaks, which can't be reduced when only one lens is used.
Spherical Lens : A spherical lens has a spherical curvature on the refracting surface. The spherical lens is firstly divided into convex and concave lenses, and again divided into plano, double and meniscus from the first division.
Aspherical Lens : This lens is made of curved surface other than spherical surface. It is designed to reduce the number of lenses by minimizing spherical aberration and to bring the focus to one, resulting in a clean image with minimal distortion.
Cylindrical Lens : Cylindrical lens focuses or magnifies light only within one dimensional single axis of the light source. These cylindrical lenses are used to focus light on thin lines in the field of optical metrology, laser scanning, spectroscopy, laser diodes, aco-optic and optical processor applications. N-BK7 glass, UV fused silica or CaF2 are used as the material for the cylindrical lenses.
Achromatic Lens : Achromatic lens has an excellent off-axis performance and designed to have a constant focal length regardless of aperture and operating wavelength. It is manufactured in doublet or triplet and suitable for applications requiring better color correction in the visible wavelength range. These lenses are often used in applications requiring more analytical observation, such as microscopes and medical devices.