LE5656 25.4 mm Dia. CaF2 Positive Meniscus Lens; EFL=750mm Uncoated

The LE5656 is a spherical lens with a convex-concave design, sourced from Thorlabs. This lens boasts a 25.4 mm diameter and a positive meniscus shape, making it suitable for a variety of optical applications. The lens's base shape is circular, and it has an effective focal length (EFL) of 750mm, providing a long focal length for precise optical focusing.

The lens is made from CaF2 (Calcium Fluoride) material, identified as "caf2 mal-1963" in the material database. This material is known for its excellent transparency in the ultraviolet, visible, and near-infrared regions, making the LE5656 a versatile choice for various wavelength applications up to 4000nm.

The lens's geometry includes a thickness of 3.7mm at the edge and 4mm at the center. The inner and outer radii are not specified, indicating that they may not be a significant factor in the lens's performance or application. The back focal length (BFL) is 744.2mm, slightly shorter than the EFL, which is typical for meniscus lenses.

Notably, the LE5656 is uncoated, which may affect its performance in certain applications. Coatings are often applied to lenses to enhance their durability, reduce surface reflections, or alter their wavelength response. However, an uncoated lens can be advantageous in specific situations, such as when minimal reflection or dispersion is required.