The SLB-20-40N is a Plano-Concave Lens, a type of spherical lens, sourced from OptoSigma. This lens has a base shape of a circle and is uncoated. The lens is designed with a diameter of 20.0 mm and a thickness edge of 4.6 mm, while the thickness at the center is 2.0 mm. The effective focal length (EFL) of this lens is -40.0 mm, making it a negative or diverging lens.
The lens is made of n-BK7 Schott, a high-quality optical glass known for its excellent transparency and low auto-fluorescence. The radius of curvature for this lens is -20.76 mm on the first surface, and the back focal length (BFL) is -41.3 mm. The lens does not have any inner or outer radius, indicating a uniform curvature.
The lens is designed to operate at a wavelength of 546.1 nm. The provided web link leads to the vendor's page, where users can find more information about the lens and its availability.