Alfa Chemistry uses the high-purity chemically polycrystalline inert material zinc sulfide (ZnS) to customize infrared optics. Made by a chemical vapor deposition (CVD) process, ZnS has high transmittance and is a widely transmitted infrared material. Alfa Chemistry has two grades of ZnS materials: multispectral (MS) ZnS and forward-looking infrared (FLIR) ZnS. All custom ZnS optics are rigorously tested by skilled experts at cutting-edge metrology facilities so that customer needs will be met. Contact us as soon as possible for your service!
Our Services
Alfa Chemistry offers customization services for high quality ZnS optical components including windows, lenses and prisms that can be manufactured to your custom specifications. Our custom optics options include uncoated and coated. A common optical coating is a broadband anti-reflective coating designed to improve optical performance at certain wavelengths. Our typical manufacturing specifications are listed below, if your requirements are not mentioned below, please contact our technical sales team and they will guide you through your inquiry.
ZnS Windows
| Diameter Range | 5 mm ~ 100 mm |
| Diameter Tolerance | ± 0.1 mm |
| Centre Thickness | up to 50 mm |
| Centre Thickness Tolerance | ± 0.05 mm |
| Clear Aperture | 90% |
| Centration Tolerance | 1 arc minute |
| Form Error | better than λ/4 (633nm) over aperture |
| Surface Radius Tolerance | 1 fringe over aperture |
| Linear Dimension | up to 100 mm |
| Linear Tolerance | ± 0.1 mm |
| Angular Tolerance | 5 arc minutes |
| Edge Finish | ground |
| Chamfer | 0.3x0.3@45° |
| Surface Quality | 40-20 scratch/ dig |
ZnS Prisms
| Length of Hypotenuse | up-to 100 ± 0.1 mm |
| Length of Sides | up-to 100 ± 0.1 mm |
| Thickness | 30 ± 0.05 mm |
| Angle Tolerance | better than 1 arc minute |
| Edge Finish | ground, blacked |
| Clear Aperture | 90% of entrance dimensions |
| Chamfer | 0.3x0.3@45° |
| Form Error | better than λ/4 @633 nm |
| Surface Quality | 20-10 scratch/dig |
ZnS Spherical Surface Lenses
| Focal Length | up-to 5000 ± 0.1mm or 1% whichever largest |
| Back Focal length | up-to 5000 ± 0.1mm or 1% of focal length |
| Radius of curvature, S1/S2 | up-to 5000 ± 1 fringe across surface |
| Form error, S1/S2 | better than λ/4 (633nm) over aperture |
| Centration (Arc Second) | less than 60 |
| Edge Thickness | up-to 50 ± 0.1mm |
| Length of Aperture | minimum 1mm or 1% of centre thickness |
| Width of Aperture | up-to 100 ± 0.1mm |
| Diameter | up-to 100 ± 0.1mm |
| Clear Aperture | 90% of diameter |
| Edge Finish | blacked, ground |
| Chamfer | 0.3x0.3@45° |
| Surface Quality | 20-10 scratch/dig |
Applications:
- Systems with Visible and Infrared Sensors: Due to its wide transmission band and low absorption, MS ZnS is frequently utilized in systems with visible, MWIR, and LWIR sensors.
- Military Systems: In military systems, FLIR ZnS can be utilized as a front optical component. It is harder and more fracture-resistant, more suited for use as a front optical element, and more resistant to chemicals and particles.
ZnS's Optical Properties
FLIR ZnS is tougher than MS ZnS. FLIR ZnS is often used to make front lenses for infrared windows and thermal imaging cameras because of its higher resistance to the harsh environment of the wire beam and its excellent light transmission in the 8 ~ 12 LWIR range. Multispectral ZnS can be used in multi-wavelength applications because of its low stiffness and strong transmission in the visible, MWIR and LWIR wavelength ranges.
Below is a quick description of ZnS's optical characteristics. For more information on the properties of ZnS materials please click here.
| FLIR ZnS | MS ZnS | |
|---|---|---|
| Transmission Range | 1.0 to 13 µm | 0.37 to 13.5 µm |
| Refractive Index | 2.192@10.6 µm | 2.20084@10 µm |
| Melting Point | 1827 ℃ | 1827 ℃ |
| Density | 4.08 g/cm3 | 4.09 g/cm3 |
| Hardness | Knoop 240 with 50g indenter | Knoop 160 with 50g indenter |
If you need technical advice, please contact our technical team to learn more about our high-quality services.