This is a G313205322 Double-Concave Lens, a high-quality optical component sourced from Qioptiq Photonics. The lens has a base shape of a circle and is designed for use in the 450-700nm wavelength range, making it suitable for a wide range of optical applications.
The lens is made from N-BK7, a popular optical glass known for its excellent optical properties. It has a diameter of 22.4mm and a center thickness of 1.5mm. The lens's effective focal length (EFL) is -20mm, indicating its double-concave design. The first radius of curvature (R1) is -20.833mm, and the second radius of curvature (R2) is 20.833mm, both of which contribute to the lens's double-concave shape.
The lens features a broadband anti-reflection coating on both the front and back surfaces. This coating, identified as 'qio bbar arb2visnbk7', is designed to reduce surface reflections and increase transmission in the visible spectrum.