This is a Si-px-12.7-12.7 12.7 mm Dia. Silicon Plano-Convex Lens, sourced from Alkor Technologies. The lens is uncoated and features a spherical shape, making it suitable for a wide range of optical applications. The lens has a diameter of 12.7 mm and a thickness at the edge of 2 mm, while the thickness at the center is 2.7 mm. The effective focal length (EFL) of this lens is also 12.7 mm.
The lens is made of silicon, specifically silicon sal vil 1957, and is designed to work with a wavelength of 10600 nm. The base shape of the lens is circular, and it does not have any inner or outer radius specified, indicating a uniform curvature. The lens is a Plano-Convex type, meaning one side is flat while the other side is curved.
The vendor, Alkor Technologies, indicates that this item is currently in stock, and further information about it can be found on their website at http://www.alkor.net/silicon_lenses_pcx.html.