This is the PLCX-25.4-51.5-UV, a Plano-Convex Spherical Lens with a diameter of 25.4 mm, sourced from CVI Laser Optics. The lens is designed for use with a wavelength of 266 nm and is made from UVFS material, specifically identified as "UVFS MAL-1965".
The lens geometry is characterized by a thickness of 2.4 mm at the edge and 4 mm at the center, with a radii of curvature of 51.5 mm on the curved surface. The effective focal length (EFL) of this lens is 103.1 mm. The lens is uncoated, offering a clear, unaltered optical path.
The lens is available from the vendor and is currently in stock, according to the weblink provided. The weblink also leads to a comprehensive catalog of CVI Laser Optics' products, offering further information and resources for users.