This is a Plano-Concave Spherical Lens, type LP11-50-200, sourced from CeNing Optics. The lens has a base shape of Circular, with a diameter of 50.8 mm and a center thickness of 2 mm. The effective focal length (EFL) of this lens is -200mm, making it a negative or diverging lens.
The lens is made of N-BK7 Schott, a popular optical glass due to its excellent optical properties and wide transparency range. The radius of curvature for this lens is -103.75 mm for the concave surface. The lens does not have any coating, as indicated by the empty "coating" field in the item data.
This lens is designed for use with a wavelength of 546.1 nm, which is in the middle of the visible light spectrum. It is suitable for use in various applications that require a diverging lens, such as in imaging systems, beam expanders, and other optical instruments.
Please note that the item data indicates that this lens is in stock and available for purchase. For more information, you can refer to the vendor's website through the provided weblink.