the specification of our achromatic lens as follow:
Material: Bk7,Quartz,Caf2,Crystal
Diameter:5mm-300mm
Diameter tolerance:0.01mm-0.1mm
Edge Thickness:1mm+/-0.10mm
Focal length:0.1%-2%
Surface quantity:80/50 to 20/10
Centration:1-3Arc minutes
Fringes:1-5 Coating:No or AR