Bi-Concave lenses have the same radii on both sides of the lens, and the function is similar to plano-convex lenses by causing collimated incident light to diverge. Bi-Concave lenses are often used to expand light or increase focal length, such as beam expanders and projection systems. These lenses are available uncoated or with a variety of antireflection coatings optimized in the VIS (400~700nm)；NIR (650~1050nm) and SWIR(1000~1650nm). Also we can design and produce according to the needs of customers.