Double concave lens usually be used with the other lens. Special application include laser beam expandar, optics character card reader, viewer and projection system.
Item
Specifications
Material
Fused Silica; N-BK7（H-K9L) or others
Diameter tolerance
+0.0/-0.2mm
Thickness tolerance
±0.2mm
Centration
<3min
Focus length tolerance
±2%
Surface quality
60/40
Clear aperture
85%
Bevel(face width×45°)
0.2~0.4mmor specified by
customer
Coating
Specified by
customer