BK7 Bi Concave Lens is an optical diverging element engineered to spread incoming light beams in a controlled and predictable way. Using BK7 optical glass as the substrate, it ensures excellent transmission in visible and near-infrared ranges while maintaining stable refractive performance. The bi-concave geometry allows symmetrical beam expansion with reduced aberration, making it suitable for imaging calibration, laser alignment systems, and laboratory optical setups. Advanced polishing and interferometric testing ensure surface accuracy and consistency across production batches.