AC254-500-A-ML 25.4 mm Dia. N-BK7/SF2 Mounted Achromatic Doublet; EFL=500mm 400-700nm

The AC254-500-A-ML is a high-quality achromatic doublet lens from Thorlabs, designed with a 25.4 mm diameter and a focal length of 500mm. This lens is specifically engineered for use in the 400-700nm spectral range, making it ideal for a wide range of applications in the visible light spectrum.

The lens is constructed from two types of glass: N-BK7 from Schott and SF2 from Schott. N-BK7, also known as Borosilicate Crown, is a popular optical glass due to its excellent optical properties and durability. SF2, or Dense Flint, is a high-index glass with a high Abbe number, making it suitable for use in achromatic doublets.

The lens features a front and back coating of tho ac400-700-a, which is a broadband anti-reflection coating designed for use in the 400-700nm range. This coating helps to reduce surface reflections, improving transmission and overall performance.

The geometry of the lens is carefully designed to provide optimal performance. The edge thickness is 5.6mm, while the center thicknesses are 4mm and 2mm. The lens features three radii of curvature: r1 is 337.3mm, r2 is -186.8mm, and r3 is -557.4mm. The inner and outer radii are both 0mm, indicating a flat surface.

This lens is a mounted doublet, meaning it comes pre-mounted in a housing for easy integration into optical systems. The housing provides mechanical stability and alignment, simplifying the process of building and maintaining complex optical systems.