This is the 21-912 model from Edmund Optics, a 25mm Dia. UVFS Aspheric Lens with an effective focal length (EFL) of 25mm and a numerical aperture (NA) of 0.48, specifically designed for use with UV light with a wavelength of 285nm.
The lens is made of syn hpfs7980 corning, a high-performance fused silica material known for its excellent transmission properties in the UV range. The aspheric design of the lens helps to reduce spherical aberration, providing superior image quality compared to traditional spherical lenses.
The lens has a diameter of 25mm and a thickness of 4.7mm at the edge, with a center thickness of 12mm. The front and back surfaces of the lens are coated with edm uv 250-425nm coating, which enhances its transmission properties in the UV range from 250 to 425nm.
The lens has a k1 value of -0.82, indicating a slight negative curvature, and a k2 value of 0, indicating no asphericity in the second order. The front and back focal lengths are 1.878008e-05m and 3.222988e-08m respectively, and the lens has a back focal length of 17mm.
This lens is currently in stock and available for purchase through the Edmund Optics website.