This is a Plano-Concave lens, a type of spherical lens, sourced from Qioptiq Photonics. The lens has a base shape of a circle and a diameter of 25.4 mm. The center thickness of the lens is 1.5 mm. The effective focal length (EFL) of this lens is -500mm, making it a negative or diverging lens. This lens is designed to work optimally with light in the wavelength range of 450-700nm, which covers the visible light spectrum.
The lens is made of N-BK7, a type of glass commonly used in optical applications due to its excellent optical properties. The lens is coated with qio bbar arb2visnbk7 on both the front and back surfaces, which enhances its durability and performance in the visible light spectrum.
The item data also provides the radius of curvature (R1) of the lens, which is -260.39 mm. The inner and outer radii are both 0 mm, indicating that this lens does not have any curvature on its inner surface.