*Material:BK7 or other materials
*Focal length:+/-1%
*Length tolerance:+0.0 ~ -0.1mm
*Width tolerance:+0.0 ~ -0.1mm
*Center thickness tolerance:+/-0.1mm
*Surface Figure:lambda/2 at 633nm on plano side
*Surface quality:60-40 stratch/dig
*Clear Apenture>90%
*Chamfer:0.25mm at 45 degrees typical
*Coating:optional
Plano-Concave Lens has a negative focal length and is typically used to cause a collimated  beam to divergeas in a Galilean type beam expander or Telescope. Because the spherical aberration of the Plano-Concave is negative, it can be used to balance the aberration of other lenses.This lens is widely use in optical display systems, projection optics systems, imaging and laser measureemnt systerms.