H-K9L Plano-concave Lenses, Uncoated/AR400-1650nm
H-K9L plano-concave lenses convert collimated parallel light into diverging rays. The diverging light converges backward at the virtual focal point of the lens, delivering a negative focal length. The lens is configured with one plano surface and one concave surface.
A plano-concave lens can diverge collimated beams from a virtual focal point and is widely used in Galilean beam expanders. For installation, align the concave surface towards the incident light and the plano surface toward the target focal plane. With negative focal length and negative spherical aberration, plano-concave lenses can compensate for aberration generated by other lenses in the optical system.
When choosing between plano-concave and biconcave lenses for diverging collimated incident light, plano-concave lenses are generally selected if the required magnification is less than 0.2 or greater than 5; biconcave lenses are preferred for magnification between the two values.
K9L is one of the most commonly used optical glasses for manufacturing high-quality optical components. When the superior properties of UV fused silica — such as high transmittance in the ultraviolet range and low thermal expansion coefficient — are not required, H-K9L is the preferred material.
Parameters
| Material | H-K9L optical glass |
| Irregularity (P-V) | λ/4@632.8 nm |
| Design Wavelength | 587.6 nm |
| Surface Quality | 60-40 |
| Diameter Tolerance | + 0.0/- 0.1 mm |
| Center Thickness Tolerance | ± 0.2 mm |
| Focal Length Tolerance | ± 2 % |
| Centering Tolerance | < 3 arcmin |
| Refractive Index | 1.5168 |
| Clear aperture | > 90% |
| Abbe | v = 64.17 |
| Bevel | 0.2 mm X 45° |
| Coating | Uncoated, Ravg < 0.5%@400~700 nm, Ravg < 0.5%@650~1050 nm, Ravg < 0.5%@1000~1650 nm |
Model
| Dia.*, mm | Focal Length, mm | Coating |
| Φ25 | -25.4/-31.5/-40/-50/-63/-80/-100/-125/ -160/-200/-250/-400/-500/-1000 | Uncoated, Ravg < 0.5%@400~700 nm, Ravg < 0.5%@650~1050 nm, Ravg < 0.5%@1000~1650 nm |
| Φ40 | -50/-63/-80/-100/-125/-160/-200/-250/-500 | |
| Φ50 | -63/-80/-100/-160/-250/-500 |
* Other Dia. Upon request.