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Fused Silica / Fused Quartz

Fused silica is a high-purity, non-crystalline material manufactured through oxidation of raw silica in a flame hydrolysis process, while fused quartz is fabricated by the melting of naturally occurring quartz.  Each process yields specific characteristics optimized for use within a given range of the UV, Visible and Near-Infrared portions of the spectrum.  While either material may be suitable for use in a given application, the below categories offer additional information on their specific benefits. Esco is pleased to provide links to the manufacturer’s material data sheets for further information.

Ultraviolet (UV) Fused Silica

Optimum Transmission Range:

Ideal Applications:

 180 nm - 2.0 µm

 Deep UV transmission elements

 Minimum scattering systems


UV fused silica provides excellent transmission into the deep UV.  Its outstanding homogeneity, lack of fluorescence and resistance to thermal shock makes it ideal for applications demanding superior wavefront performance when exposed to high-power lasers and challenging environmental conditions.  With the removal of metallic impurities, certain grades of UV fused silica are tailored for use in 248nm and 193nm semiconductor wavelengths and demonstrate superior throughput for these applications.

Manufacturer's Material Data (PDFs)

Infrared (IR) Fused Silica

Optimum Transmission Range:

Ideal Applications:

 250 nm - 3.6 µm

 Superior optical quality and IR transmission


The near infrared portion of the spectrum suffers from absorption bands in the presence of OH- ions.  IR grade fused silica is specifically manufactured to remove these impurities thus offering substantially higher transmission over UV grade fused silica up to 3.5 microns.  This characteristic, along with resistance to thermal shock and high homogeneity, makes it a cost-effective option when compared to other IR materials for applications including NIR process control and inspection for machine vision, high resolution SWIR imaging, as well as, remote sensing and metrology.

Manufacturer's Material Data (PDFs)

Optical Grade Fused Quartz

Optimum Transmission Range: Ideal Applications:
 270 nm - 2.5 µm  Condenser optics not concerned with scatter or distortion
 High temperature and pressure applications
  Optical flats, microscope slides, and sight glasses

Due to metallic impurities and OH- content, optical grade fused quartz does not boast the range of transmission offered by UV and IR grade fused silica.  However, despite this shortcoming, fused quartz still offers superior thermal shock and chemical resistance, as well as, high transmission from 270nm to 2.5 microns.  For applications within this range, fused quartz provides a cost-effective option to the more expensive grades of fused silica.

Manufacturer's Material Data (PDFs)