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Potassium Bromide(KBr) window

Potassium Bromide(KBr) window

Potassium Bromide(KBr) optical window


 Single crystal of Potassium Bromide(KBr),  High Purity >99.99% 

Other Names

Potassium Bromide window, KBr window

Crystal structure


Applicable wave band

0.25μm ~ 25μm

Refractive Index

1.525  at 10μm, Nd=1.49025

Melting Point



2.753g / cc

Absorption coefficient

3×10-6 @ 1064nm;14×10-6cm-1 @ 10.6μm
Thermal Conductivity

4.816 W/mK @ 319K

Thermal expansion coefficient

43×10-6 /°K @ 300K

Knoop hardness

7 in <100>

Dielectric constant

4.9 at 1MHz

Young's modulus

26.8 GPa

Shear modulus

5.08 GPa

Maximum size

 Diameter 100mm (Single crystal)

Material Standard Size Surface quality
Potassium Bromide(KBr) window φ12.7mm x 3.0mm
φ25.4mm x 3.0mm
φ25mm x 5.0mm
φ50mm x 5.0mm
φ50.8mm x 5.0mm
φ100mm x 5.0mm
10 x 10 x 1.0mm
12.7 x 12.7 x 3.0mm
25.4 x 25.4 x 3.0mm
Polishing:             Double side optical-polished or Epi-polished
Roughness:          Ra<30nm or Ra<10nm 
Size Tolerance:          +/-0.1mm
Thickness Tolerance: +/-0.1mm or +/-0.05mm
Parallelism:           1 minute, 30 seconds, 5 seconds or higher
Surface Finish:      80-50, 60-40, (scratch-dig)
Surface Figure:      1/2λ, 1/4λ or higher
Chamfer:                0.25mm × 45°
Coating:                 Upon requirements

Potassium Bromide(KBr) is the most commonly used spectrophotometer for IR spectrophotometers. It is commonly used in FTIR spectroscopy. Potassium Bromide window has a larger spectral band range than Sodium Chloride window, and has excellent transmission between 250nm-26μm. Within this range, its refractive index is between 1.46-1.59. Potassium Bromide is water-soluble, so its surface should not be in contact with moisture. Potassium Bromide windows have good resistance to mechanical shock and can be used at high temperatures of 300 °C. KBr window is one of the most useful materials for general purpose spectral windows and applications that have no significant effect on humidity sensitivity. 
We can customize different size and thickness of Potassium Bromide(KBr) optical window upon requirements, such as Potassium Bromide(KBr) round wafer, Square substrate and Cylinder, or Punch holes and other shapes.

Contact Us

  • Tel: (+86) 1506 0796 451
  • Fax: (+86) 0597 2212602
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  • Main office: A7, No. 501, Denggaoxi Road, Xipi street, Xinluo District, Longyan, Fujian, China