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Sodium Chloride(NaCl) window

Sodium Chloride(NaCl) window

Sodium Chloride(NaCl) optical window


 Single crystal of Sodium Chloride(NaCl),  High Purity >99.99% 

Other Names

Sodium Chloride window, NaCl window

Crystal structure


Applicable wave band

0.25μm ~ 16μm

Refractive Index

1.49065 at 10.6μm

Melting Point



2.17g / cc

Absorption coefficient

7×10-6 cm -1 at 1.06μm
Thermal Conductivity

1.25 W m-1 K-1 at 273K

Knoop hardness

18.2 in <100>

Dielectric constant

5.9 at 1MHz

Thermal expansion coefficient

44×10-6 /℃

Maximum size

 Diameter 100mm (Single crystal)


Material Standard Size Surface quality
Sodium Chloride(NaCl) window φ12.7mm x 3.0mm
φ25.4mm x 3.0mm
φ25mm x 5.0mm
φ50mm x 5.0mm
φ50.8mm 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 requirments

Sodium chloride (NaCl) crystal is a material commonly used in FTIR spectroscopy. It is also a relatively low cost cubic crystal material with excellent transmission between 250nm-16μm. In such a large transmission range, the refractive index is between 1.4-1.6. Sodium chloride windows are sensitive to thermal shock, but can be used at temperatures up to 400 °C. Its density is 2.17 g/cm3 and Knoop hardness is 18.2. It is hygroscopic, so the substrate must not contain any moisture. NaCl window is one of the most useful materials in general-purpose spectral windows and applications that have no significant effect on moisture sensitivity.
We can customize different size and thickness of Sodium Chloride(NaCl) optical window upon requirements, such as Sodium Chloride(NaCl) round wafer, Square substrate and Cylinder, or Punch holes and other shapes.

Contact Us

  • Tel: (+86) 1506 0796 451
  • Fax: (+86) 0597 2212602
  • Email:
  • Work Time ( GMT +8 ):
  •    9 AM ~ 6 PM, Monday to Friday
  • Main office: A7, No. 501, Denggaoxi Road, Xipi street, Xinluo District, Longyan, Fujian, China