SLB-20B-40NIR2 20.0 mm Dia. x -39.7 mm FL; Coated; Double-Concave Lens 750-1550nm

The SLB-20B-40NIR2 is a high-quality double-concave lens, designed and manufactured by OptoSigma. This lens, with a diameter of 20.0 mm, is specifically engineered for use within the wavelength range of 750-1550nm, making it ideal for near-infrared applications.

The lens features a base shape of a circle, with a center thickness of 2mm and an edge thickness of 4.4mm. The effective focal length (EFL) is -39.7mm, and the back focal length (BFL) is -40.3mm. The radii of curvature for the first and second surfaces are -41.52mm and 41.52mm, respectively.

The lens is made from n-BK7 Schott, a popular optical glass due to its excellent optical properties and high Abbe number. The lens is coated with Opt IR2, a broadband anti-reflection coating that enhances transmission and reduces surface reflections, ensuring optimal performance in its designated wavelength range.

This lens is a spherical lens, which is a type of lens where the two surfaces are parts of spheres. Spherical lenses are the simplest type of lens and are widely used in various optical systems due to their ease of manufacturing and versatility.

The lens data indicates that this is a concave-concave lens, meaning both surfaces are curved inward. This type of lens is often used to diverge light or reduce the optical power of a system.