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All Products / Optics / Optical Lenses / Aspheric Lenses / Infrared / Germanium Infrared (IR) Aspheric Lenses
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TECHSPEC® components are designed, specified, or manufactured by Edmund Optics. TECHSPEC® components are designed, specified, or manufactured by Edmund Optics. Learn More

25mm Dia x 20mm FL 8-12μm Coated, Ge Aspheric Lens

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Stock #68-253 Clearance 3-4 days
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€1.534,70
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€1.534,70
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Specifications

General

Type:
Aspheric Lens

Physical & Mechanical Properties

Diameter (mm):
25.00 +0.0/-0.1
Centering (arcmin):
≤5
Clear Aperture CA (mm):
22.5
Edge Thickness ET (mm):
2.5
Center Thickness CT (mm):
3.70 ±0.10
Bevel:
Protective as needed
Edges:
Diamond Turned
Shape of Back Surface:
Plano

Optical Properties

Effective Focal Length EFL (mm):
20.00 @ 4000nm
Numerical Aperture NA:
0.63
Back Focal Length BFL (mm):
19.08
Substrate: Many glass manufacturers offer the same material characteristics under different trade names. Learn More
Germanium (Ge)
Aspheric Design Wavelength (nm):
4000
Asphere Figure Error, RMS @ 632.8nm:
λ/6
Coating:
BBAR (8000-12000nm)
Coating Specification:
Ravg <3.0% @ 8 - 12μm
Surface Quality:
60-40
f/#:
0.79
Wavelength Range (nm):
8000 - 12000
Conjugate Distance:
Infinite

Regulatory Compliance

RoHS 2015:
Compliant
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Certificate of Conformance:
View
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Reach 235:
Compliant
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Product Details

  • Diffraction Limited Performance
  • Variety of Coating Options
  • Full Prescription Data Available
  • Due to material supply chain disruptions with germanium, there may be increased lead times and price changes on our germanium products. For more information, please contact our customer service team.
  • Edmund Optics has limited remaining inventory of this part number and no raw material available to supply more once this is depleted.  Please contact our Product Support Engineers to help with an alternate solution for your needs. Customer Service can provide you the latest price and availability.

TECHSPEC® Germanium Infrared (IR) Aspheric Lenses provide diffraction-limited focusing performance over a broad spectral range in the Mid and Long Wave infrared regions. Ideal for monochromatic light sources, such as quantum cascade lasers, these lenses offer a high-performance alternative to standard plano-convex lenses. 
The lenses are available in a 12.5, 25, or 50mm diameter. TECHSPEC® Germanium Infrared (IR) Aspheric Lenses are available uncoated, or with BBAR coating options. 

Uncoated germanium has transmission of <50%, so custom anti-reflection (AR) coatings should be considered if specifying an uncoated lens. Each BBAR coated lens offers >95% transmission, making it ideal for integration into a variety of OEM applications. For custom design or coating options, please contact our Sales Department.

Technical Information

AR COATED GERMANIUM

Typical transmission of a 3mm thick Ge window with BBAR (3000-5000nm) coating at 0° AOI.

The blue shaded region indicates the coating design wavelengh range, with the following specification: 

Ravg <3% @ 3000 - 5000nm

Data outside this range is not guaranteed and is for reference only.

Click Here to Download Data

Typical transmission of a 3mm thick Ge window with BBAR (3000-12000nm) coating at 0° AOI.

The blue shaded region indicates the coating design wavelengh range, with the following specification: 

Ravg <5.0% @ 3 - 12μm

Data outside this range is not guaranteed and is for reference only.

Click Here to Download Data

Typical transmission of a 3mm thick Ge window with BBAR (8000-12000nm) coating at 0° AOI.

The blue shaded region indicates the coating design wavelengh range, with the following specification: 

Ravg <3.0% @ 8 - 12μm

Data outside this range is not guaranteed and is for reference only.

Click Here to Download Data

Special Handling

Germanium Optics Handling and Cleaning Guidelines

Germanium optics require special handling and cleaning procedures. Always wear gloves during handling to prevent contamination, and wash hands afterward. Avoid contact between Germanium dust and the eyes, skin, or clothing. When not in use, store optics sealed and covered at temperatures between 20°C and 25°C. Do not expose them to temperatures exceeding 100°C when in use.

Handling Guidelines

  • Always wear gloves to prevent damage from skin oils.
  • If Germanium dust is present, take the following precautions:
    • Wear safety glasses to protect eyes.
    • Use a dust mask or face mask to avoid inhalation.
    • Wear gloves to prevent skin contact.
  • Maintain storage temperature between 20°C and 25°C with humidity below 30%.
  • Wrap Germanium optics in a lens cloth or pouch and seal in a container when not in use.
  • Germanium is brittle and heavy — always place it on soft surfaces and avoid dropping it.

Approved Cleaning Solvents

  • Ethanol
  • Isopropyl Alcohol
  • Methanol
  • Reagent-Grade Acetone
  • Liquid CO₂
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