The LB1258-C is a high-quality bi-convex lens from Thorlabs, designed for use in a wide range of optical applications. This lens is made from N-BK7 Schott glass, a popular material due to its excellent optical properties and high damage threshold.
The lens features a diameter of 0.5 inches (12.7 mm) and a thickness of 1.8 mm at the edge, increasing to 2.8 mm at the center. The effective focal length (EFL) is 20 mm, and the radii of curvature for the front and back surfaces are 30.4 mm and -30.4 mm respectively. The back focal length (BFL) is 28.9 mm.
The LB1258-C is coated with Thorlabs' proprietary anti-reflection coating, designed to reduce surface reflections and increase transmission in the 1050-1700 nm range. This coating is applied to both the front and back surfaces of the lens.
The lens is spherical in shape, a common design that provides a large field of view and low distortion. This makes it suitable for use in imaging systems, beam shaping, and other applications where a high-quality, low-distortion image is required.