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Ge Optics

Ge (Germanium) in the range of 2-12μm is the most commonly used material for the production of spherical lenses and windows for high efficiency infrared in the imaging system operating in both 3-5 and 8-12μm.

Due to the wide transmission range and visible opacity, Ge (Germanium) is very suitable for the manufacture of optical components of infrared lasers and optical systems. The high refractive index and minimal surface curvature of Ge (Germanium) make it ideal for making low-power imaging systems. Honour Optics is the professional high quality Chinese infrared Germanium lenses and custom infrared spherical/aspherical/cylindrical Germanium lenses manufacturer, Welcome to consult the price of wholesale infrared Germanium lenses.

Ge (Germanium) is a kind of material that is relatively hard and has high density. The Knoop Hardness of Germanium is approximately twice that of MgF2 (Magnesium Fluoride), making it ideal for IR applications requiring rugged optics. Germanium’s high density (5.33 g/cm^3) should be considered when designing for weight-sensitive systems.

Ge (Germanium) is non-hygroscopic, non-toxic, and has low optical dispersion, excellent surface hardness, and good strength. Ge (Germanium) also has a minimal chromatic aberration due to low dispersion. This material is somewhat brittle and tends to chip and spall.

Ge (Germanium) has the highest refractive index; mostly coatings will be needed, Honour Optics provides Anti-reflection coatings at 2-14µm, 3-5µm, 8-12µm, BBAR coating or DLC/AR depending on your custom application.

Ge (Germanium) is severely affected by temperature, the transmission rate decreases with the increase of temperature. This means Ge (Germanium) has good thermal conductivity. It is subject to thermal runaway. Germanium transmits over 45% between 2-14μm up to 45⁰C but transmission degrades slowly at 100⁰C then more rapidly above 200⁰C. As such, Germanium window should be better to use at temperatures below 100°C.

Customizable Infrared and Broadband Germanium optics blocks UV and visible light, as well as IR up to about 2μm.
Its high index is desirable for the design of lenses that might not otherwise be possible.
It has nearly the highest density of the IR-transmitting materials, a consideration when designing for weight restricted systems.

It is subject to thermal runaway; the hotter it gets, the more the absorption increases. Pronounced transmission degradation starts at about 100°C and begins rapidly degrading between 200°C and 300°C, resulting in possible catastrophic failure of the optic.
Ge is generally less expensive than ZnSe and Cleartran.
Ge is diamond turnable.

Products manufactured: Lenses, Aspheric Lenses, Binary (Diffractive) Lenses, Windows, Optical Beamsplitters, Optical Filters, Wedges. Welcome everyone to wholesale infrared large size Germanium optics.

Surface finish: Typical specifications for surface quality in the infrared are 40-20 or 60-40 scratch-dig in the 2 to the 7μm spectral region and 60-40 scratch-dig for the 7-14μm area, depending upon system performance requirements. Diamond turned surface finishes of 120 Angstroms RMS or better are typical.

Surface figure: Surface figure: In the infrared, typical surface figure ranges from 1/2 wave to 2 waves @0.6328μm depending on the system performance requirements.

AR coating options: Typically available coatings for Germanium include BBAR for 3 to 5μm, 8 to 12μm, and the 3 to 12μm spectral regions. Many application specialized bands are possible between the 2 and 14μm.

Tab. 1. Main Properties of Ge (Germanium)

Atom number 32
Atom weight 72.6
Crystal structure diamond cubic
Lattice constant at 25°C, A 5.657
Density (298 K), g/cm3 5.323
Atomic density, atoms/cm3 4.42 x 1022
Surface tension, liquid at melting point, mN/m 650
Modulus of rupture, MPa 72.4
PSI 1.05 x 104
Mohs hardness 6
Vickers hardness, 25 gm load, kg/mm2 746 (52 Ohm x cm)
Fracture toughness, MPa1/2 1.004 (110 fracture plane)
Thermal shock resistance 125°C
Poisson's ratio, 125-375 K 0.278
Melting temperature, °C 937
Boiling temperature, °C 2830
Specific thermal capacity (0-100°C), kal/g x degree 0.074
Latent heat of fusion:
kal/mol 8100
J/g 466.5
Latent heat of vaporization, J/g 4602
Coefficient of linear thermal expansion (293 K), cm/degree 6.1 x 10-6
Heat capacity, 25°C, J/(kg x K) 322
In water at 20°C, g/100cm3 insoluble
In acids soluble

Tab. 2. Refractive index Ge (Germanium)

µm No µm No µm No
2.058 4.102 2.153 4.0919 2.313 4.0786
2.437 4.0708 2.577 4.0609 2.714 4.0562
2.998 4.0452 3.303 4.0369 4.258 4.0216
4.866 4.017 6.238 4.0094 8.660 4.0043
9.720 4.0034 11.04 4.0026 12.00 4.0023
13.02 4.0021

Tab. 3. Specification of Ge optics

Specification Typical Level High precision
Sizes 2mm-400mm 2mm-500mm
Diameter tolerance +/-0.1mm +/-0.05mm
Thickness tolerance +/-0.1mm +/-0.05mm
Surface quality, scr/dig 60/40 20/10
Surface flatness(lambda) L/4 L/10
Parallelism 3 arc min 30 arc sec
Clear Aperture 80% 90%
Chamfer 0.25mm at 45 deg 0.15mm at 45 deg
Coating As requested As requested

Transmission Spectrum

high quality Chinese infrared germanium lenses transmission spectrum

Customizable Infrared and Broadband Germanium optics is a most widely used infrared material for windows and optical elements in thermal imaging systems. Germanium has excellent transmission across 2-14μm waveband and can be used in both mid-wave infrared and long-wave infrared systems. Honour Optics is the professional high quality Chinese infrared Germanium lenses and custom infrared spherical/aspherical/cylindrical Germanium lenses manufacturer, Welcome to consult the price of wholesale infrared Germanium lenses.

Ge (Germanium) is a high index material that is useful for ATR prisms for spectroscopy. Its refractive index is such that Ge (Germanium) makes an effective natural 50% beamsplitter without the need for coatings. It is also used extensively as a substrate for production of optical filters, CO 2 laser optics, optical coatings for beam splitters and other IR optical applications. Germanium covers the whole of the 8-14 micron thermal band and is used in lens systems for thermal imaging. It can be AR coated with diamond producing an extremely tough front optic. Welcome everyone to wholesale infrared large size Germanium optics.

Honour Optics produces high-quality Germanium with theoretical transmission and excellent homogeneity. Both monocrystalline and polycrystalline are available. Blanks, windows, lenses, and prisms can be made according to your specifications, with the diameter up to about 500mm.