IR Grade Fused Silica Windows and Lenses

Posted by Steve Rowe on

Esco Optics is pleased to announce the addition of IR grade fused silica lenses and windows to its catalog of stock optical components. Manufactured using IR grade fused silica, these optics allow for exceptional transmission up to 3 microns. Combined with a low coefficient of thermal expansion, superior homogeneity and low birefringence, IR grade fused silica is an outstanding alternative to significantly more expensive IR materials. Fused silica is made by melting highly pure silica through a flame hydrolysis process where it oxidizes and forms an amorphous (crystal-free) structure. Applications of interest include process control and inspection using machine vision, high resolution SWIR imaging, remote sensing and metrology. 

Shop IR Catalog Optics now

IR Fused Silica Window IR Fused Silica Window Round  IR Fused Silica Plano-Convex Lens

This product line includes an extensive selection of plano-convex lenses from 0.5”-3” diameter, as well as, windows ranging from 0.5”- 4.0” diameter and 1.0”- 3.5” square. All items are available online and our sales engineers can assist with any questions or requests for custom configurations and anti-reflective coatings.

UV Fused Silica transmission chart, IR fused silica transmission, Fused Quartz transmission range

Optimum Transmission Range:

Ideal Applications:

 250 nm - 3.6 µm

Superior optical quality and IR transmission

Solar simulation optics, SWIR imaging, remote sensing, metrology, defense optics


Maximum Visible Transmittance
Maximum UV Transmittance
Maximum Infrared Transmittance
Homogeneity: AA,A,C,F (by size)
No Striae in Use-Axis
Homogeneity Certified in Off-Axis: A,C,F (by size)
Minimum Birefringence
Minimum Fluorescene
UV Laser Resistance


Infrared Spectrum

Low Coefficient of Thermal Expansion: A hallmark of fused silica is its thermal stability. Whereas other optical materials will lose their surface accuracy when subjected to large changes in temperature, fused silica is known for its ability to resist thermal shock and expansion. This important property makes it a perfect choice for mirror substrates when considering the application of either a metal or dielectric coating. The low CTE also helps maintain the precision of an optics transmitted wavefront distortion over a range of temperatures.

Minimal/No Fluorescence: In the design of every optical system, the signal-to-noise ratio is an important factor. When exposed to high intensity radiation such as UV light, many materials will absorb the energy and re-emit it, thereby fluorescing. This effect introduces unwanted noise into the system which degrades the overall signal and reduces the effectiveness of the instrument. Fused silica provides extremely low, and in many cases, no fluorescence in the presence of such radiation. This specific characteristic has earned fused silica the reputation as the material of choice for laser applications.

High Chemical Resistance: Fused silica is chemically inert and will not react with a wide array compounds, including most acids in very high concentrations, with the exception of hydrofluoric acid. Such durability is useful when fused silica is employed as a window in harsh environments or when used as a laboratory tool in contact with caustic chemicals. This resistance also protects the integrity of an optic’s surface polish assisting both the flatness and transmitted wavefront distortion.

Esco Optics also provides many custom optics in a variety of materials and tolerances. If you can’t find what you are looking for in IR catalog please contact us for a custom quote.

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