LB1723-B N-BK7 Bi-Convex Lens; Dia:2 in; f=60.0 mm ARC 650-1050nm

The LB1723-B is a high-quality bi-convex lens, designed and manufactured by Thorlabs, a leading global supplier of photonics equipment. This lens boasts a diameter of 2 inches, or 50.8 millimeters, and a focal length of 60 millimeters, making it suitable for a wide range of optical applications.

The lens is crafted from N-BK7, a type of borosilicate glass known for its excellent optical properties. This material is particularly prized for its low coefficient of thermal expansion, high homogeneity, and excellent transmission in the visible and near-infrared regions of the spectrum. The N-BK7 designation refers to the specific composition of the glass, which is a standard in the optical industry.

The lens features a spherical geometry, with both faces curved outward. The first radius of curvature (R1) is 59.3 millimeters, while the second radius of curvature (R2) is -59.3 millimeters. This bi-convex design helps to minimize spherical aberration, ensuring that the lens delivers sharp, clear images.

The lens has an effective focal length (EFL) of 60 millimeters and a back focal length (BFL) of 55 millimeters. The edge thickness of the lens is 3 millimeters, while the center thickness is 14.4 millimeters. The lens is coated with a broadband anti-reflection coating, designed to reduce surface reflections and improve transmission in the 650-1050 nanometer range.