BK7 Double-Concave Lenses
Double concave lens(DCV) is similar with plano concave lens. The focus length is negative. It can make parallel light diverge outside. The two sides have same radius of curvature. Double convex lens generally used for expanding beam of light and projection etc. BK7 double concave lens has excellent transmittance from visible to near infrared wavelength (350-2000nm).