The LE1985-C is a 50.8 mm diameter Spherical Lens with a Positive Meniscus shape, sourced from Thorlabs. This lens is designed for use in the 1050-1700nm wavelength range, making it suitable for a variety of applications in the near-infrared spectrum.
The lens is made from N-BK7 Schott glass, a popular material due to its excellent optical properties and wide transmission range. The lens has a double-sided Anti-Reflection coating, denoted as 'tho c bbar', which further enhances its performance by reducing surface reflections.
The lens geometry includes an outer diameter of 50.8 mm, with a center thickness of 5.1 mm and an edge thickness of 3 mm. The Effective Focal Length (EFL) is 300 mm, and the Back Focal Length (BFL) is 293.8 mm. The lens surface radii are 100.1 mm for the first surface and 279.1 mm for the second surface.
This lens is a Convex-Concave design, also known as a Meniscus lens, which is characterized by a center thickness greater than the edge thickness. This design provides a gradual transition between the two surfaces, reducing optical aberrations and improving image quality.