Home / Custom / Optical Components / Optical Spherical Lens / Double Concave Lens 
A double concave lens/mirror has a negative focal length, thereby causing collimated incident light to diverge. The double concave lens/mirror has an equal radius of curvature on both sides of the lens. They are generally used to expand light or increase focal length in the existing system, such as beam expander and projection systems.
| Items | Parameters |
|---|---|
| Material | Optical glass/ Fused silica/ sapphire etc. |
| Diameter | 2mm~300mm |
| Diameter Tolerance | ±0.05mm(≤50mm) |
| ±0.1mm(＞50mm) | |
| Focal Length | -50mm~-2000mm |
| Focal Length Tolerance | ±0.2%（＜10mm） |
| ±0.5%（＜10mm-1000mm） | |
| ±1%（＞1000mm） | |
| Center Thickness | 2mm~20mm |
| Surface Quality | 60/40, 40/20, 20/10 |
| Surface Accuracy | λ/2~λ/10@632.8nm, 532nm |
| Clear Aperture | >85% |
| Center Deviation | <3arc min~ 30arc sec |
| Coating | According to customer requirements. |
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