Drum and half-drum lenses are modified spherical lenses with comparable uses as spherical lenses, such as enhancing coupling at the interface of the fiber and the transmitter or detector. Drum lenses are a variant of spherical lenses in which the outermost part of the sphere is removed by grinding a section of the ball to a smaller diameter. The drum lens's cylinder-shaped outer diameter makes it simpler to mount and align with the optical system. The drum lens's two spherical lens shapes still work well for endoscopic and fiber optic coupling applications. As the name suggests, a half drum lense is a drum lens that has been chopped in half. A full drum lense with two spherical surfaces is used to create semi-drum lenses, and one of the spherical surfaces is polished to a planar plane to create a thin plano-convex lense.
Alfa Chemistry can provide drum and semi-drum lenses that are manufactured specifically for each customer and their needs. Our highly skilled professionals test each product in our state-of-the-art metrology lab to ensure it meets standards. For more information about your needs for the custom drum and half-drum lenses, please contact our technical sales team.
Our Capabilities
Standard sizes for our selection of custom drum and half-drum lenses range from 1.0 mm to 5.0 mm, and other custom sizes are also available. There are several materials that can be used to create custom drum and half-drum lenses: N-BK7 is typically used for visible applications; For applications operating at deep UV wavelengths down to 185 nm, quartz and UV fused silica materials are used; These materials are also available for NIR wavelengths up to 2000 nm. High refractive index materials such as Schott and Ohara are available for very short focal lengths and minimal spherical aberration. Custom solutions for full-surface antireflective (AR) coatings are available for all lenses.
Below are examples of our standard manufacturing capabilities.
| Diameter | 2.0 mm |
| Diameter Tolerance | +0/-50 μm |
| Radius | 1.25 mm |
| Radius Tolerance | +0/-1.5 μm |
| Length | 2.50 mm |
| Length Tolerance | ±3 μm |
| Surface Quality | 40-20 |
| Coating Options | Uncoated or AR coating |
| Material Options | Schott glass, N-BK7, Quartz and UV fused silica, etc |
Quality Assurance
Each custom drum or half drum lense is carefully tested to all applicable standards using state-of-the-art metering equipment. We inspect and scrutinize every product before it's shipped to customers, so customers can have complete confidence that the optics they order will be the best fit for their application.
Alfa Chemistry is always looking to expand and work with customers to achieve their specifications, so please feel free to contact our technical sales team for more information and guidance on your enquiry.