A plano-concave lens is a negative-focal-length optical element characterized by one flat surface and one inwardly curved (concave) spherical surface. As one of the most fundamental diverging components in optics, it spreads incoming collimated light outward—increasing beam diameter and effectively reducing power density. It is frequently employed to counteract excess positive optical power within an optical system.
Manufactured from high-grade optical materials—such as N-BK7 glass or fused silica—these lenses undergo precision grinding and polishing. Available in a wide range of specifications covering ultraviolet through infrared wavelengths, they serve as ideal components for laser systems, imaging correction, and beam shaping applications.
| Parameter | Standard Specification | Precision Specification | Ultra-Precision Specification |
| Diameter Range | 5-150mm | 3-150mm | 2-120mm |
| Focal Length Range | -10mm 至 -1000mm | -5mm 至 -1500mm | -3mm to -2000mm |
| Diameter Tolerance | +0.0/-0.1mm | ±0.05mm | ±0.02mm |
| Center Thickness Tolerance | ±0.1mm | ±0.05mm | ±0.02mm |
| Radius of Curvature Tolerance | ±0.5% | ±0.2% | ±0.1% |
| Flat Surface Figure | λ/4 @ 632.8nm | λ/10 | λ/20 |
| Concave Surface Figure | λ/4 @ 632.8nm | λ/10 | λ/20 |
| Centration Error | <3 arc minutes | <1.5 arc minutes | <0.5 arc minutes |
| Surface Quality | 40-20 scratch-dig | 20-10 | 10-5 |
| Edge Treatment | Protective Chamfer | Precision Chamfer | Stress-Free Chamfer |
| Surface Quality | >90% of Diameter | >95% of Diameter | >98% of Diameter |
