Optical Lenses
A Meniscus Lens, also called Convex-concave Lens, is an optical lens that have one concave side and one convex side, forming a crescent-like profile. Depending on the curvature of each surface, meniscus lenses can be classified as positive (converging) or negative (diverging). The special shape of meniscus lenses allow the the shortening or extension of focal length without introducing substantial spherical aberrations.
Spherical abberation is an optical error that exists in all sphere-shaped optics where parallel lights at different distances from the optical axis fail to focus at the theoretical focal point. This error occurs in both the transverse and longitudinal directions, causing blurring of the image. Spherical aberrations are more significant at large numerical apertures as the light gets farther away from the center than in the case of small NA. Mensicus lens can be used to focus or diverge light with decreased spherical aberrations, without the need to reduce the numerical aperture, as the double-curved surfaces of the meniscus lens allow the optical engineer to adjust how light is bent at each interface. With adequately engineered surface curvature, it is possible to improve spherical aberrations.
While meniscus lenses are more expensive than PCX or PCV lenses, for some applications, it might be much more efficient to use a meniscus lens either from the perpective of costs or performance. For example, especially in infrared applications like CO2 lasers for laser processing, where tight focusing and high beam quality is required, a meniscus lens works much better than a conventional plano-convex lens.
A positive meniscus lens, also referred to as a converging meniscus lens, has a more strongly curved convex surface than its concave surface, and the center of the lens is thicker than the edge. Positive meniscus lenses are used to bring lights together to a focal point, similar to a traditional plano-convex lens, but for applications where reduced spherical aberration and hence better image quality is critical.
A negative meniscus lens, or diverging meniscus lens, features a more steeply curved concave surface than its convex side, which means its edge is thicker than the center. Negative meniscus lenses are used to diverge incoming light and are typically used to increase the focal length of an optical system or to correct aberrations in multi-lens systems.
Hangzhou Shalom EO offers Custom Positive and Negative Meniscus Lenses made from various substrate materials, including Fused Silica, N-BK7, Chalcogenide glass, BaF2, CaF2, MgF2, Germanium, ZnSe, GaAs, Sapphire, etc. We provide diameters from 1.0mm to 300mm, coating optics include BBAR, V-coating, and single-layer MgF2 coating.
