The LB1157-C is a high-quality bi-convex lens from Thorlabs, designed with a spherical geometry and a circular base shape. This lens is fabricated from N-BK7 glass, a popular material in the optical industry due to its excellent optical properties. The lens has a diameter of 6.0 mm and a thickness that varies from 1.5 mm at the edge to 5.1 mm at the center.
The LB1157-C lens boasts an effective focal length (EFL) of 400 mm, making it suitable for a wide range of applications. The radii of curvature for the first and second surfaces are 9.9 mm and -9.9 mm, respectively, resulting in a back focal length (BFL) of 9.2 mm. The lens does not have any inner or outer radius, indicating a uniform thickness across the lens.
This lens is coated with a broadband anti-reflection coating, specifically designed for the wavelength range of 1050-1700 nm. This coating, denoted as "tho c bbar", reduces reflection and increases transmission, enhancing the overall performance of the lens.