The biconcave lens, also named double concave lens, is usually made of flint glass and used for beam divergence. It’s focal length is negative but the parallel incident ray diverges outward. The two sides of the biconcave lens curvature radius can be equal or not. Combined with plano-convex lens, it is generally used in beam expanders, projection optical systems and optical viewers, etc.
Oplens can not only customize the common plano-concave lens of N-BK7 or fused quartz, but also customize the biconcave lens of any glass material.