Germanium (Ge)

Overview

Germanium (Ge) is a standard high-index substrate for LWIR imaging, compact infrared optical layouts, and protective windows that need strong refractive power in the 8-12 µm region. Because the index is high and the substrate is dense, engineers usually review both optical performance and mount design together rather than selecting the material on wavelength alone.

Key Material Reference

Selected Refractive Index Reference

The refractive-index points below are taken from the local RII dataset at 293 K. They are suitable for page-level comparison, but final optical modeling should use the exact temperature and coating condition of the released design.

Typical Applications

• LWIR thermal imaging lenses
• Germanium windows with protective coatings
• Compact high-index IR systems
• Infrared camera and sensor optics

Engineering Notes

Germanium is usually selected when compact optical power matters, but the high index also raises reflection and coating sensitivity. Engineers should confirm band, coating stack, mount preload, and thermal behavior before releasing a drawing. Review alternative substrates from the materials index and downstream part options under products if the system may also fit ZnSe or Si.

Procurement Checklist

• Specify the working band and whether the part is for an imaging path or a protective window only.
• Include diameter, clear aperture, thickness, quantity, and coating target in the RFQ.
• State whether DLC or other protective coatings are required for field use.
• Call out any thermal cycling, shock, or packaging constraint that affects mount design or inspection scope.

Request Engineering Review

Send wavelength band, dimensions, coating target, quantity, and application notes through the contact page for a practical Germanium review.