Germanium Plano-Convex Lenses

Overview

Germanium plano-convex lenses are positive focal length spherical lenses for infrared imaging, thermal measurement, sensing, monitoring, and spectroscopy systems. One surface is flat and the other surface is convex, allowing the lens to focus collimated infrared radiation or collimate radiation from a point source.

Germanium is widely used in MWIR and LWIR optical systems because it combines high refractive index, useful infrared transmission, good mechanical strength, and practical thermal conductivity. It is not intended for visible transmission optics, so wavelength range and system use should be confirmed before selection.

Why Germanium PCX Geometry Matters

The plano-convex form is often selected when a system needs simple focusing, collimation, or beam collection with a positive focal length element. Germanium supports compact infrared lens designs, but coating, temperature behavior, and mounting stress should be reviewed with the optical layout.

Quick Specifications

Parameter	Guidance
Material	Single-crystal Germanium (Ge)
Lens Type	Plano-convex spherical lens
Typical Transmission Range	Approximately 2-12 µm, depending on material grade, thickness, surface quality, and coating
Common Coating Options	AR coating for 3-5 µm or 8-12 µm infrared bands
Diameter Range	1-200 mm commercial grade; 2-200 mm precision and high-precision grades
Diameter Tolerance	±0.1 mm, ±0.025 mm, or ±0.01 mm depending on grade
Surface Quality	60/40, 40/20, or 20/10 depending on inspection grade
Chamfer	0.1-0.5 mm × 45°

Typical Standard Options

Diameter	Focal Length	Lens Type
6 mm	15 mm	Plano-convex lens
10 mm	3.8 mm	Plano-convex lens
12 mm	50.8 mm	Plano-convex lens
12.7 mm	15 mm, 20 mm, or 25 mm	Plano-convex lens
18.5 mm	40 mm	Plano-convex lens
20 mm	20 mm or 50.8 mm	Germanium PCX lens
22 mm	20 mm	Plano-convex lens
27 mm	27 mm	Plano-convex lens

Typical Applications

• Thermal imaging cameras and LWIR lens assemblies
• Infrared thermometry and non-contact temperature measurement
• IR monitoring, surveillance, and remote sensing systems
• Infrared spectroscopy and analytical optical paths
• CO2 laser-related infrared optics when absorption, coating, thermal load, and power density are reviewed

Engineering Notes

Germanium has a high refractive index, so uncoated surfaces can create significant reflection loss. AR coating is normally recommended for practical MWIR and LWIR systems. Engineers should confirm wavelength band, focal length, diameter, center thickness, surface quality, surface figure, centration, coating type, operating temperature, and environmental conditions.

For adjacent infrared material options, review Germanium material guidance or browse IR optical components. To request drawing review, send the target wavelength, focal length, tolerance level, coating requirement, quantity, and drawings through the contact form.