Cesium iodide (CsI), an infrared-transmitting substance that transmits from the ultraviolet all the way to the far infrared, is used by Alfa Chemistry to create customized infrared optics for parts in a range of spectrophotometers. Of all typical infrared materials, it possesses the deepest known infrared transmission. All custom CsI 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 offer premium CsI components made to your exact specifications, including windows, lenses, and prisms. In an atmosphere with airborne particles, CsI materials may degrade. As a result, for material exposure, we highly advise using a protective coating that normally consists of a broadband anti-reflective coating and a moisture resistant anti-reflective coating.
The table below lists our typical manufacturing requirements. Our skills are constantly improving, so if your requirements fall outside of the above, please contact our technical sales team who will be able to assist you as we have many years of experience in this field.
CsI Windows
The most commonly requested specifications for an CsI window are as follows:
| Diameter Range | 5 mm ~ 30 mm |
| Diameter Tolerance | ± 0.1 mm |
| Centre Thickness | up to 10 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 30 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 |
CsI Prisms
The most commonly requested specifications for an CsI prism are as follows:
| Length of Hypotenuse | up-to 30 ± 0.1 mm |
| Length of Sides | up-to 30 ± 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 | 1 fringe from test flat |
| Surface Quality | 40-20 scratch/dig |
CsI Ground Blanks
The most common specifications for CsI ground blanks are as follows.
| Diameter Range | less than 5 mm to 30 mm |
| Diameter Tolerance | better than ± 0.5 mm |
| Centre Thickness | up to 10 mm |
| Centre Thickness Tolerance | better than ± 0.5 mm |
| Clear Aperture | 90% |
| Linear Dimension | up to 30 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:
- Scintillators: CsI can be doped with thallium to produce CsI(Tl), which is one of the brightest scintillators with an emission wavelength tha fits well with silicon photodiodes.
- Secure Imaging Systems: It is possible to employ CsI arrays, which are frequently thallium-doped, in security imaging systems, such as baggage scanners.
- Infrared Spectroscopy: Infrared spectroscopy windows frequently employ CsI because of its broad transmission band. Since the material deteriorates when exposed to moisture, it is frequently covered and kept in desiccators to reduce contact with the environment.
CsI's Optical Properties
Because CsI is such a delicate material, polishing it is challenging. Although it is extremely resilient to mechanical and thermal damage, it deteriorates in some atmospheric situations, particularly when it comes into touch with moisture. Water soluble substance Csl transmits light from the ultraviolet (0.25 µm) to the far infrared (55 µm). CsI has the largest transmission range of any commonly used IR material, with a transmittance of over 80% between 0.40~40 µm.
Fig 1. UV-Vis spectrophotometer showing the optical band-gap energy of CsI:Tl crystals and transmittance (inset). (Saengkaew P, et al. 2016)
Below is a quick description of Csl's optical characteristics. For more information on the properties of Csl materials please click here.
| Transmission Range | 0.25 to 55 µm |
| Refractive Index | 1.73916@10µm |
| Melting Point | 621 ℃ |
| Density | 4.51 g/cm3 |
| Hardness | Knoop 20 with 200g indenter |
If you need technical advice, please contact our technical team to learn more about our high-quality services.
Reference
- Saengkaew P, et al. (2016). "Impact of Precursor Purity on Optical Properties and Radiation Detection of CsI:Tl Scintillators." Applied Physics A 122: 729.