... : optical glass 3), Light transmittance: 85% Concave-convex Lens1), Material: various optical glass.2), Shape: concave, convex, flat, etc.3),Type: Flat ... -convex lens, flat-concave lens, double-convex lens, double-concave lens, etc4), Usage: optical achromatic.5), Structure ... : concave-convex.6), Accuracy (the highest): N=2/ N=0.5 ...