Plano-concave lens, N-BK7, Ø 12.7 mm, f = -50 mm, ARB2-VIS

Plano-concave singlet in N-BK7, Ø 12.7 mm, focal length -50 mm. ARB2-VIS broadband AR coating. Negative focal length: diverges the beam, for beam expanders and to shorten system length.