Combatting the global shortage of Germanium for IR lenses

Historically the most common material utilised for Long Wave InfraRed (LWIR) lenses for imaging in the 8-14um waveband, is Germanium.

The reasons for this are simple. Germanium is a unique semiconductor material known for its exceptional optical properties arising from its high refractive index and excellent transparency in the LWIR spectral region. It is an ideal material for detecting heat signatures because it allows IR radiation to pass through while blocking visible light. Unlike conventional optical glass, which blocks infrared radiation, Germanium allows high throughput transmission to the sensor with minimal distortion. This enables high contrast, sharp focus imaging, and the ability to detect even the smallest temperature differences.

In recent years, Germanium has become scarce and expensive primarily due to China’s export restrictions (implemented in August 2023), highly concentrated supply chains, and fast growing demand for use in both optical and electronics applications.

With the aim to secure their supply chain and stabilise costs, we are seeing a significant rise in customer enquiries for LWIR lenses which do not use any Germanium within the optical system. The choice of materials offering suitable properties for LWIR wavelengths is limited but there are other options. The problem is that a lot of these alternative materials come with their own set of problems.

One of our preferred material types to turn to is Chalcogenide glasses, however these glass types are extremely soft and scratch very easy. To produce a lens that will last any meaningful amount of time, particularly in any kind of rough environment, it is important that hard protective coatings are applied to all external facing surfaces. While hard protective coatings can increase the cost of Chalcogenide lenses, the critical thing is that the materials are readily available and the costs consistent which can give the customer peace of mind that their supply chain will not fall apart due to a lack of optical material.

To learn more about our custom IR lens design service please visit https://www.resolveoptics.com/oem-design-manufacture/