Product Overview

H-K9L (N-BK7) is the most commonly used optical glass for preparing high-quality optical elements. From the visible near-infrared (350-2000nm), it has excellent transmissivity. When the additional advantages of ultraviolet fused silica are not needed (it has good transmissivity and low thermal expansion coefficient in the ultraviolet band), H-K9L is generally chosen. When deciding whether to use a flat concave lens or a double concave lens to diverge incident light, if the absolute conjugate ratio (object distance divided by distance) is close to 1, it is more inclined to choose a double concave lens. When the absolute magnification is less than 0.2 or greater than 5, it is more inclined to choose a plano concave lens.

Product Features

The design wavelength of the lens is 546.1 nm (e line of the green mercury spectral line), and since the focal length varies with wavelength, when used for other wavelengths, its focal length also changes accordingly. It has a lower cost compared to quartz components.

Application scope

Double concave lenses are often used in systems for beam expansion or increasing focal length, and can also be used in laser beam expansion, optical readers, observers, and projection systems.

Specification parameter list