IR Window Capabilities

Sydor Optics manufactures windows using materials that can transmit into the IR spectrum, 0.750μm – 15μm

IR windows

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Our IR windows are used in camera turrets for aircraft, marine and ground based vehicles, sensing applications, IR imaging and other Electro Optical payloads. We service defense, law enforcement, imaging and other industries.

Silicon, germanium, sapphire and zinc sulfide/selenide are IR materials that are currently available at Sydor.

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Sydor IR Materials Capabilities

Sydor Optics is one of the leading firms polishing flat IR materials. We have experience producing IR components in silicon, germanium, sapphire, and zinc sulfide/selenide. We have manufacturing processes and metrology tools to produce and accurately measure coated or uncoated components. Our capabilities include:

  • Double-sided polishing for exceptional transmitted wavefront and parallelism.
  • Metrology to measure transmitted wavefront of IR windows, as the parts are used, and taking into account the two surfaces and material homogeneity.
  • Ability to measure windows up to 14”, ~350mm.
  • High-volume production of IR products.

Demonstrating Transmitted Wavefront with an IR Interferometer

IR InterferometerOur IR Interferometer allows Sydor to ensure that the IR windows we produce will perform as designed at specified transmitted wavefront. The IR Interferometer allows us to test and measure the window’s performance at 3.39μm and calculate the transmitted wavefront for other IR wavelengths, allowing us to precisely qualify the IR window.

Our IR Interferometer can measure windows up to 14”, ~350mm, which allows us to ensure we meet specification on even the largest IR window requests.

Superior Transmitted Wavefront and Parallelism, from Prototype to Production

Sydor is home to the largest collection of double-sided polishing machines in North America. Our expert technicians and double-sided polishing process ensures we produce parts with fractional transmitted wavefront and exceptional parallelism. Our tight process control further ensures our results are repeatable batch to batch and order to order.

Benefits of Double-Sided Grinding and Polishing at Sydor

Production Volume – Quickly

Sydor uses batch-type processing that facilitates economy of scale. This enables us to produce IR windows in the quantity you need, in the most efficient way possible, saving time and money.

Excellent Transmitted Wavefront

Paired with our IR Interferometer, our double-sided grinding and polishing process achieves excellent transmitted wavefront, creating IR windows that meet or exceed specification.

Reduced Processing Cost

We have the ability to produce high quality windows in large volumes with our collection of double-sided grinding and polishing machines. This further reduces unit costs by controlling processing costs.

IR Material Applications


For handheld, ground-based vehicles and aircraft & marine-mounted vehicles:

  • Thermal imaging
  • Night vision
  • Targeting sights
  • Camera turrets for VIS & IR imaging
  • EO/IR surveillance systems
  • Threat warning instruments

Law Enforcement

For handheld, ground-based vehicles and aircraft & marine-mounted vehicles:

  • Thermal imaging
  • Night vision

Search & Rescue

For handheld, ground-based vehicles and aircraft & marine-mounted vehicles:

  • Thermal imaging for firefighting
  • Night vision


  • Power line maintenance
  • Process control
  • Mineral & gas detection
  • Agriculture

About the IR Materials Available

Silicon Characteristics

  • Cubic in nature and will not exhibit birefringence
  • High environmental durability
  • Silicon is lower in density making it ideal for weight-sensitive applications when compared to other popular IR materials such as germanium and zinc selenide
  • Thermal stability
  • More cost-effective for mid-wave applications than other IR materials

Germanium Characteristics

  • Highest refractive index and lowest optical dispersion of commonly available IR-transmitting materials
  • Germanium is relatively hard with high-density, making it ideal for IR applications requiring rugged optics
  • Generally, an anti-reflection coating is recommended on germanium windows for sufficient transmission in the region of interest
  • Subject to decreases in transmission as temperature increases, therefore, it must be used at temperatures below 100°C
  • Germanium makes an effective 50:50 beamsplitter without the need for coatings

Sapphire Characteristics

  • Not reactive with air, water, heat, oxidizers, corrosives, or non-corrosives
  • Extremely hard and durable
  • High melting point of 2,040°C
  • Very low transmitted wave distortion
  • Wide optical transmission range

IR-Grade Fused Silica Characteristics

  • A very low coefficient of thermal expansion
  • Outstanding transmittance in the UV, DUV, visible, and Infrared spectrums
  • Refractive index from 1.440791 – 1.588999
  • Excellent performance in applications that use the 2µm wavelength spectrum

Zinc Sulfide Characteristics

  • Reduces scatter and offers low absorption
  • Excellent transmission from 0.36 to 12µm
  • Generally a lower cost compared to other IR materials
  • The multispectral version is especially appropriate for applications in multiple spectrums that require a single aperture for beam path for several wavebands

Zinc Selenide Characteristics

  • Appropriate choice for CO2 lasers and thermometry and spectroscopy
  • Extremely low coefficient of thermal expansion
  • Excellent homogeneity and uniformity in a wide range of spectrums

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