The 69-681 is a 25mm diameter, 250mm focal length plano-convex lens, sourced from Edmund Optics. This lens is made of silicon, specifically silicon sal vil 1957, and does not have any coating.
The lens's geometry is characterized by a 2.87mm thickness at the edge, increasing slightly to 3mm at the center. The effective focal length (EFL) is 250mm, and the radius of curvature (R1) is 604.4mm. The back focal length (BFL) is 249.12mm, and both the inner and outer radii are 0mm, indicating a planar surface on the opposite side of the convex surface.
This lens is designed for use with a wavelength of 10600nm. Its spherical shape and silicon material make it suitable for a wide range of optical applications. However, please note that this lens is uncoated, which may affect its performance in certain environments or when used with specific light sources. Always ensure to consider the lens's properties and your specific application requirements before making a purchase.