Silicon Material Infrared Window , Ir Cut Filter With Lower Refractive

Basic Information
Place of Origin: Wuhan,China
Brand Name: Wuhan Siwer Optics
Minimum Order Quantity: 5 pieces
Price: 20-98USD/piece
Packaging Details: 1.Tissue paper. 2.Plastic foam packaging film. 3.Hard carton box with quakeproof filler
Delivery Time: 3-5 weeks
Payment Terms: T/T, Western Union
Supply Ability: 3000 pieces/month
Detail Information
Material: Silicon Size Tolerance: +/-0.1mm
Chamfer: 0.2-0.5mm Surface Quality: 40/20
Surface Flatness: Lambda/4 In 25.4mm Parallelism: 0.01mm
Standard Coating: AR/AR@3-5um Size Range: 3-300mm
Usage: Infared System
High Light:

optical window


infrared system protectd window

Product Description

Infrared imaging system Silicon protected windows

Silicon (Si) is one of the hardest minerals and optical materials available for use in the NIR (1µm) to about 6µm. Optical quality Silicon is usually doped (5 to 40 ohm cm) to prevent absorption bands within the transmission waveband. Silicon has a lower refractive index than germanium and has a lower density that makes for less weighty optical designs.

Silicon is ideal for use as windows in the 3 to 5µm (MWIR) waveband and as substrate for optical filters. This waveband (3 to 5µm) is important for the detection of sources radiating at a black body temperature of 700K, such as the muzzle flash from guns, such as sniper rifles and mortar pieces.Its transmission is about 50% within the 1 to 6µm and above 50µm, which will mean that anti-reflection coatings are required to improve the transmission.

The MWIR optical components manufactured from silicon, or other suitable material, can be used to build a unit that can detect the muzzle flash from, for example, a sniper rifle. The detection of snipers is of great importance in, for example, Afghanistan, as many military lives are being lost to snipers. The gun flash from a sniper rifle has a distinct spectral distribution from the hot gases that are emitted. These gasses are, for example, CO and H2 together with CO2, N2 and H2O that produce distinct emissions in the 3 to 5µm band.

Silicon has a high thermal capacity that makes it ideal for laser mirrors.


The MWIR optical components manufactured from silicon, for example, need to be tested to ensure that they meet the design specification. MWIR interferometers are used to determine the surface quality in terms of the number of fringes the surface is from the required. Interferometers can measure the difference relative to flat or spherical surfaces. Additional converging or diverging optics are required to ensure that the interrogation beam is retro-reflected back along the incident path for convex and concave surfaces. As the MWIR interferometer is used to determine the accuracy of surfaces, then its components must be manufactured to a higher specification than that needed for the surface. These reference surfaces must be traceable to a national standard, such as NPL in the UK. Some typical applications where Silicon is used are MWIR Gun Flash Detection, Imaging systems, and MWIR Interferometers.



Silicon window is the best protective window in the imaging system with working wavelength of 3-5um. Compared with other infrared materials, it has the highest cost performance, and its low density can effectively reduce the weight of equipment.


Silicon Material Infrared Window , Ir Cut Filter With Lower Refractive 0 Silicon Material Infrared Window , Ir Cut Filter With Lower Refractive 1

Optical Properties of Silicon Window

Material Single Crystal Germanium
AR Coating Range 3-5um
Reflectance over
AR Coating Range @ 0° AOI

Ravg < 1.5%,3-5um

Transmission over
AR Coating Range @ 0° AOI
Tavg > 97%,3-5um
Diameter Tolerance +0.0/-0.1 mm
Thickness Tolerance ±0.1 mm
Parallelism 3 arc min
Surface Quality 60-40 Scratch-Dig
Surface Flatness
(Plano Side)
λ/2 at 633nm
Surface Irregularity
(Peak to Valley)
λ/2 at 633nm
Clear Aperture >Ø10.16 mm (Ø1/2" Lenses)
>Ø20.32 mm (Ø1" Lenses)
Design Wavelength 10.6 μm


Transmittance of Antireflection coatings:

Silicon Material Infrared Window , Ir Cut Filter With Lower Refractive 2 Silicon Material Infrared Window , Ir Cut Filter With Lower Refractive 3

Silicon properties:

Chemical Formula
Molecular Weight
Crystal Class
Lattice Constant, Å
Density, g/cm3 at 293 K
Dielectric Constant for 9.37 x 109 Hz
Melting Point, K
Thermal Conductivity, W/(m K)
at 125K
at 313K
at 400K

Thermal Expansion, 1/K
at 75K
at 293K
at 1400K

-0.5 x 10-6
2.6 x 10-6
4.6 x 10-6
Specific Heat, cal/(g K)
at 298K
at 1800K

Debye Temperature, K
Bandgap, eV
Solubility in water
Knoop Hardness, kg/mm2
Mohs Hardness
Young's Modulus, GPa
Shear Modulus, GPa
Bulk Modulus, GPa
Poisson's Ratio


Infrared Elements Selection Guide

Silicon Material Infrared Window , Ir Cut Filter With Lower Refractive 4


Silicon Material Infrared Window , Ir Cut Filter With Lower Refractive 5

What's the way of shipping?
We accept DHL, Fedex, TNT, UPS, SF, EMS etc. If you have your own express account, it's great.


How to pay?

(1) T/T, PayPal, West Union,etc

(2) Bank Fee: West Union-USD30.00(≤USD3000.00),

T/T-USD20.00+, PayPal-5%. Please consult the local bank.

What's the deliver time?
For inventory: the delivery time is around 5 workdays.

Customized products: the delivery time is 10 to 30 workdays. According to the quantity and precision.

Can I customize the products based on my need?
Yes, we can customize the material, specifications and optical coating for your optical components based on your needs. OEM is available.

Contact Details