Plano-concave lens, N-BK7, Ø 25.4 mm, f = -1000 mm, ARB2-VIS

Plano-concave singlet in N-BK7, Ø 25.4 mm, focal length -1000 mm. ARB2-VIS broadband AR coating. Negative focal length: diverges the beam, for beam expanders and to shorten system length.