Creating high-performance optics relies heavily on the materials used, which must be sourced from an increasingly volatile global market. One such material is germanium, commonly used in lenses for thermal imaging systems. As an expert in optical design, DIOPTIC offers a solution to reduce this dependency: germanium-free lenses.
Optical Design of Thermal Lenses
We specialize in thermographic lenses for industrial applications in a wavelength range from 2.0 to 5.5 µm. Germanium is often used as the material for the lenses. The reason: Germanium has a very good transmission in this wavelength range with a high refractive index of approx. 4. The high refractive index is the dream of every optical designer. In order to achieve a certain refractive power, the lenses must be significantly less curved, which minimizes aberrations and makes production easier. In this way, lenses with high image quality can be produced with just a few lenses – which in turn helps transmission.
Volatile Supply Chain for Germanium
While germanium is ideal for thermal lenses, its availability is tied to global market dynamics. For years, major suppliers included Russia and China. However, sourcing from Russia was halted in early 2022 due to escalating geopolitical tensions. In August 2023, China decided to restrict exports, implementing stringent licensing requirements. These changes have had a significant impact: since May 2024, the price of germanium has doubled, and lead times have stretched to up to 23 weeks, complicating the timely production of thermal lenses.
Cost Savings Through Material Substitution
In response to this situation, we have leveraged our optical and optomechanical expertise to develop germanium-free thermal lenses. This involves replacing germanium in lenses with alternatives such as zinc selenide, zinc sulfide, silicon, or calcium fluoride. These materials also offer attractive refractive indices, but require redesigning lens geometry, quantity, and arrangement to ensure the final optical systems meet the same high-performance standards. This is precisely what DIOPTIC’s experts deliver—whether designing new lenses or retrofitting existing optical systems.
Our germanium-free thermal lenses meet the same stringent customer requirements while offering shorter lead times and more predictable costs.
