The LF5469-E is a spherical lens with a concave-convex base shape and a circular design, sourced from Thorlabs. This lens boasts a diameter of 25.4 mm and a center thickness of 4 mm, with an edge thickness of 10.4 mm. The effective focal length (EFL) is -40 mm, and the back focal length (BFL) is -39.9 mm. The radii of curvature for the first and second surfaces are 308.3 mm and 15.5 mm, respectively.
This lens is crafted from Calcium Fluoride (CaF2) with the Mal-1963 material ID, making it suitable for use with a wavelength of 4000 nm. The lens is equipped with anti-reflection coatings on both the front and back surfaces, specifically the tho ecaf2arc20005000 coating, which enhances its performance in the 2000-5000 nm range.
Please note that the inner and outer radii are both 0, indicating that this lens does not have any special shaping on its edges. The lens is currently in stock and available for purchase through the provided web link.