Alfa Chemistry uses thallium bromide iodide (KRS5) material for custom infrared optics. It is made with the intention of transmitting into the deep infrared. It is most frequently employed as a spectrum infrared material because of its wide transmission band and low absorption. All custom KRS5 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 as soon as possible for your customer service!
Our Services
Alfa Chemistry has an excellent selection of made-to-order KRS5 optics, including ATR prisms, windows, and ground blanks, that can be produced to meet your precise needs. We can provide coated and uncoated options, including diamond-like carbon (DLC) coating or broadband transmission-enhancing (BBAR) coating. The table below lists our typical manufacturing requirements. If your needs are not covered by the aforementioned list, get in touch with our technical sales team. We can help you since we have a lot of experience in this area.
KRS5 Windows
The most commonly requested specifications for an KRS5 window are as follows:
| Diameter Range | 5 mm ~ 50 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 50 mm |
| Linear Tolerance | ± 0.1 mm |
| Angular Tolerance | 5 arc minutes |
| Edge Finish | ground, blacked |
| Chamfer | 0.3x0.3@45° |
| Surface Quality | 40-20 scratch/ dig |
KRS5 Prisms
The most commonly requested specifications for an KRS5 prism are as follows:
| Length of Hypotenuse | up-to 50 ± 0.1 mm |
| Length of Sides | up-to 50 ± 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 over aperture |
| Surface Quality | 40-20 scratch/dig |
KRS5 Ground Blanks
The most common specifications for KRS5 ground blanks are as follows.
| Diameter Range | less than 5 mm to 50 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 50 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: As a result of its broad transmission band, low absorption, and high refractive index, KRS5 is frequently utilized as a substrate for ATR prisms. Additionally, it serves as a transmission window for gaseous and liquid samples.
- Line Grid IR Polarizers: Wire-grid IR polarizers can be constructed using KRS5 as their substrate. Numerous applications, such as FTIR spectroscopy, medical imaging, and aerospace, make use of these polarizers.
- Non-Thermal Imaging Systems: To adjust for thermal defocus inside a system, KRS5 and germanium can be employed. It is often used as a triplet with another infrared material, zinc sulfide, to correct for chromatic aberrations that may be introduced by KRS5.
KRS5's Optical Properties
KRS5 is a deep infrared material with a high refractive index that transmits in the infrared wavelength range of 0.5 to 40 µm. In addition, it can transmit up to 70% or more. The KRS-5 material is transparent over a wide spectral range from the red visible spectrum to the far infrared spectrum. When used in combination with germanium, KRS5 can also be used in non-thermal infrared imaging systems. KRS5 is non-hygroscopic and has high chemical resistance to strong acids. KRS5 is toxic and must be handled with extreme care. Gloves should be worn and hands should be thoroughly washed after handling the optical components.
Fig 1. Spectral transparency range of selected materials used for waveguiding applications in the infrared. (Hlavatsch M, et al. 2022)
Below is a quick description of KRS5's optical characteristics. For more information on the properties of KRS5 materials please click here.
| Transmission Range | 0.6 to 40 µm |
| Refractive Index | 2.371@10 µm |
| Melting Point | 414.5 °C |
| Density | 7.371 g/cm3 |
| Hardness | Knoop 750 |
If you need technical advice, please contact our technical team to learn more about our high-quality services.
Reference
- Hlavatsch M, et al. (2022). "Infrared Spectroscopy-Quo Vadis?" Appl. Sci. 12(15): 7598.