Uncoated, Potassium Bromide (KBr) Window

Description

Shape Optics’ Potassium Bromide (KBr) Windows are high-quality optical components designed to offer exceptional transmission across a broad spectral range. These windows are particularly well-suited for applications in Fourier Transform Infrared (FTIR) spectroscopy, providing superior performance in environments where wide spectral coverage and good resistance to mechanical shock are required.

Properties and Uses

KBr windows are used primarily in FTIR spectroscopy due to their extensive spectral range and high transmission efficiency. They are ideal for applications that require precise and reliable infrared measurements. KBr windows are known for their excellent transmission from the ultraviolet (UV) to the infrared (IR) regions, making them versatile for various optical applications. However, they are water-soluble and must be protected from moisture to prevent surface degradation.

General Specifications

• Material: Potassium Bromide (KBr)
• Coating: Uncoated
• Edges: Fine Ground
• Bevel: Protective as needed
• Type: Protective Window

Physical Properties

• Density: 2.753 g/cm³
• Young’s Modulus: 26.8 GPa
• Coefficient of Thermal Expansion (CTE): 43 x 10⁻⁶/°C

Mechanical Properties

• Knoop Hardness: 7 kg/mm²
• Poisson’s Ratio: 0.203
• Surface Flatness: λ/2

Chemical Properties

Potassium Bromide is water-soluble with a solubility of 53.48 grams in 100 grams of water at 273K. This property necessitates that KBr windows be handled and stored in a dry environment to maintain their optical performance. Exposure to moisture can degrade the surface quality and reduce transmission efficiency.

Optical Properties

• Index of Refraction: 1.56
• Abbe Number (νd): 33.64
• Surface Quality: 60-40 scratch-dig

Transmission Wavelength Range

KBr windows offer an impressive transmission range from 250 nm to 26,000 nm. This broad wavelength range covers both the UV and IR spectra, making KBr windows highly versatile for a variety of optical applications. The index of refraction of KBr varies between 1.46 and 1.59 over this spectral range, ensuring high transmission without the need for anti-reflection coatings.

Conclusion

Shape Optics’ Potassium Bromide Windows are designed to provide excellent performance across a wide spectral range, making them ideal for FTIR spectroscopy and other demanding optical applications. Their high transmission, good resistance to mechanical shock, and ability to cover a broad wavelength range make them a valuable component in advanced optical systems. However, due to their water solubility, proper handling and storage in dry conditions are essential to maintain their performance.