This is the BF-px-38.1-200, a 38.1 mm diameter Plano-Convex lens made from BaF2 (Barium Fluoride) material. The lens is sourced from Alkor Technologies and is currently in stock, as indicated by its valid weblink status.
The lens features a focal length of 200mm (EFL), making it suitable for applications that require a longer focal length. The geometry of the lens includes a thickness of 2mm at the edge and 4mm at the center, with no inner or outer radius specified, indicating a simple plano-convex design.
The lens is made from BaF2, a material with a wide transmission range from UV to mid-IR, making it a versatile choice for various optical applications. However, it's important to note that this particular lens is uncoated, which may affect its performance in certain applications, particularly those involving high-intensity light sources or extreme environmental conditions.
For more detailed information, please refer to the vendor's website at http://www.alkor.net/BaF2_lenses_pcx.html.