Plano-concave lens, Fused silica, Ø 12.7 mm, f = -20 mm, mounted, ARB2-NIR

Plano-concave singlet in Fused silica, Ø 12.7 mm, focal length -20 mm, in a mount. ARB2-NIR broadband AR coating. Negative focal length: diverges the beam, for beam expanders and to shorten system length.