The 11-431 is a Plano-Convex Spherical Lens, boasting a diameter of 50.8mm and a focal length of 75mm. This lens is crafted from ZnSe (Zinc Selenide) material, specifically the connolly variant, which is known for its excellent optical properties. The lens is coated with BBAR (Broadband Anti-Reflection) coating, ensuring minimal loss of light due to reflection. This coating is designed to work within the 3-12µm wavelength range, making it suitable for a wide range of applications. The lens is circular in shape, with a thickness of 2.39mm at the edge and 5.5mm at the center. The front and back of the lens are coated with the same BBAR coating, providing consistent performance across the entire lens. This lens is sourced from Edmund Optics and is currently in stock, as indicated by its weblink status.