LBTEK Double-Concave Lenses feature two concave surfaces with equal radii of curvature, providing a negative focal length. They are commonly used for beam collimation, focal length adjustment, and image reduction or magnification. To meet different application requirements, LBTEK offers double-concave lenses made from both N-SF11 and N-BK7 glass. N-SF11 lenses, with a lower Abbe number, exhibit higher dispersion than N-BK7, making them ideal for shorter focal length designs and for use in harsh environments such as acidic or alkaline conditions. N-BK7 lenses, by contrast, are among the most widely used materials for high-quality optics, offering excellent transmission in the visible and near-infrared regions and making them suitable for a broad range of general-purpose applications. LBTEK provides both uncoated double-concave lenses and AR-coated versions optimized for 400–700 nm, 700–1100 nm, and 1100–1650 nm. All lenses are manufactured with precision and undergo strict quality control, ensuring that LBTEK delivers high-performance optical components at competitive prices.