Biconcave lens, N-BK7, Ø 12.7 mm, f = -50 mm, mounted, ARB2-NIR

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