Plano-concave lenses diverge a collimated beam from a virtual focus and are commonly used in Galilean-type beam expanders. Given their negative focal length and negative spherical aberration, plano-concave lenses can be used to balance out aberrations of other lenses in the system.

Negative Focal Length Used to Diverge Collimated Beams
Zemax Files Available
Uncoated Wavelength Range: 350 nm - 2.0 µm
A AR Coated Wavelength Range 400~700nm
B AR Coated Wavelength Range 650~1050nm
C AR Coated Wavelength Range 1000 - 1650 nm