Alfa Chemistry uses potassium bromide (KBr) crystalline materials to customize infrared optical elements. For general-purpose spectrum windows and situations where moisture sensitivity is unimportant, KBr is one of the most practical materials. Due to its broad transmission spectrum, it has optical uses in the MWIR, LWIR, UV, and visible band regions. All custom KBr optics are rigorously tested by skilled experts at cutting-edge metrology facilities, giving customers the peace of mind that their needs will be met. Contact us for your customer service as soon as possible!
Our Services
Alfa Chemistry can provide a variety of KBr infrared optical components custom manufactured to customer specific requirements, including windows, lenses, prisms, etc. We can provide coated and uncoated optical options such as broadband anti-reflective (BBAR) coatings. The table below lists our typical manufacturing requirements. If your needs are not covered here, please get in touch with our technical sales team. We have years of experience in this industry and are always working to improve our skills.
KBr Windows
| Diameter Range | 5 mm ~ 80 mm |
| Diameter Tolerance | ± 0.1 mm |
| Centre Thickness | up to 30 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 80 mm |
| Linear Tolerance | ± 0.1 mm |
| Angular Tolerance | better than 5 arc minutes |
| Edge Finish | ground |
| Chamfer | 0.3x0.3@45° |
| Surface Quality | 40-20 scratch/ dig |
KBr Prisms
| Length of Hypotenuse | up-to 80 ± 0.1 mm |
| Length of Sides | up-to 80 ± 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 | 0.2 fringe from test flat |
| Surface Quality | 40-20 scratch/dig |
KBr Ground Blanks
| Diameter Range | less than 5 mm to 200 mm |
| Diameter Tolerance | better than ± 0.5 mm |
| Centre Thickness | up to 50 mm |
| Centre Thickness Tolerance | better than ± 0.5 mm |
| Clear Aperture | 90% |
| Linear Dimension | up to 200 mm |
| Linear Tolerance | better than ± 0.5 mm |
| Angular Tolerance | better than 10 arc minutes |
| Edge Finish | fine ground N6 |
| Chamfer | 0.3x0.3@45° |
Applications:
- Fourier Transform Infrared (FTIR) Spectroscopy: In FTIR spectroscopy, IR grade KBr is frequently utilized, particularly as a substrate for beam splitters. It permits a wider 4000~400 cm-1 wavelength range.
KBr's Optical Properties
From near-UV to long-wave IR wavelengths (0.25 to 25 µm), KBr is transparent, and its high transmission zone has no noticeable light absorption lines. It is frequently employed as a component in infrared optical windows and in general spectroscopy because of its broad spectral range. Because moisture can harm the polished surface of KBr crystals, which are soluble in water, they must be kept dry. Temperatures as high as 300 °C can be used with optical KBr materials. Under controlled humidity levels, KBr optics can be polished to a high degree. It cannot be chemically polished.
Fig 1. Potassium Bromide transmits light in the visible and infrared ranges down to about 333 cm-1. (Davis A. D, et al. 2007)
Below is a quick description of KBr's optical characteristics.
| Transmission Range | 0.23 to 25 µm |
| Refractive Index | 1.527@10 µm |
| Melting Point | 2.753 g/cm3 |
| Density | 730 ℃ |
| Hardness | Knoop 7<100>with 200g indenter |
| Operating Temperature | < 300 ℃ |
If you need technical advice, please contact our technical team to learn more about our high-quality services.
Reference
- Davis A. D, et al. (2007). "Light-Dark FTIR Absorbance Difference Spectroscopy for the Study of Photosystem I." ABachelor of Science (BSc, Honours, Dept of Physics).