Infrared windows are used in camera turrets for aircraft, marine and ground based surveillance systems, sensing applications, IR imaging and other electro optical payloads. IR windows in FLIR instruments, FTIR spectroscopy, and mineral and gas detection systems serve a range of markets including military & defense, medical, industrial, and commercial applications.

Sydor Optics is one of the leading firms polishing flat IR materials. Whether your infrared application is in the NIR (0.75µm – 1µm), the SWIR (1µm – 2.7µm), the MWIR (3µm – 5µm) or the LWIR (8µm – 12µm) spectrum, we are able to shape and polish infrared materials best suited to imaging requirements. Sydor Optics has experience producing IR components in silicon, germanium, sapphire, silica, and zinc sulfide / zinc 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.

Custom Infared Window Fabrication

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.


Based upon customer demand, Sydor Optics offers Optical Windows made from the following optical substrate materials. Of course, if you don’t see a material you need, please contact a Sales Engineer, who will gladly discuss additional options that may be 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
Custom optical filter fabrication
Optical Window Manufacturing Limits
Specifications Measurements
Diameter ≤ 600mm
Length / Width ≤ 450mm x 450mm
Thickness ≤ 100mm
Thickness Tolerance ± 0.010mm [Precision]
± 0.10mm [Standard]
Cosmetics (MIL-PRF-13830B) Down to 10-5 [Precision]
60-40 [Standard]
Surface Roughness ≥ 3 Ǻ rms
Parallelism ≥ 1 arc second
Reflected Wavefront Error (RWE) - before coating ≤ 1/20 wave over clear aperture [Precision]
≤ 1 wave [Standard]
Transmitted Wavefront Error (TWE) - before coating *Interferometric Scale Factor (ISF) of 0.5 – Single-Pass ≤ 1/20 wave over clear aperture [Precision]
≤ 1 wave [Standard]
Clear Aperture ≥ 90% [Precision]
≤ 85% [Standard]

Infrared (IR) Windows

Infrared windows are often used in FLIR, FTIR spectroscopy, medical systems, thermal imaging, or other optics applications within the infrared light spectrum. IR windows can help protect your employees and equipment. Sydor Optics can custom manufacture IR windows in a variety of shapes, sizes, substrates, and coatings for various infrared applications. AR coating is available for one or both surfaces.

Window Shapes

Sydor Optics can manufacture custom optical windows — with various shapes and sizes — using CNC Glass Machining or Laser Machining capabilities to meet your specific needs

Some of the standard optical window shapes that Sydor Optics customers frequently order include:

  • Circular Windows
  • Square Windows
  • Rectangular Windows
  • Elliptical Windows
  • Custom Window Shapes


Production volume – quickly

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

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.
Precisiion optical products

Engineering value into your precision flat optics

We work with optical engineers at the inception of programs to ensure the optics are designed for manufacturability and optical performance in the application's environment.




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

Law Enforcement

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

  • Thermal imaging
  • Night vision
Search & rescue

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

Infrared Window Applications

Thermal Imaging Windows

Sensor/EO Windows

Mineral & Gas Detection Windows

Fourier-transform infrared (FTIR)

Gimbal Windows

Camera Turrets for VIS & IR Imaging

Night Vision

Optical Gas Imaging

Instrument Windows

Forward-Looking Infrared (FLIR) Windows

Threat Warning Instruments