When should sapphire be used in optical components?

A: Sapphire crystal is premium optical substrate material, and it should be chosen for optical components when your application requires extreme mechanical hardness, outstanding scratch resistance, high temperature stability and strong chemical corrosion resistance, which normal optical glass cannot satisfy.

Sapphire ranks 9 on Mohs hardness scale, only softer than diamond. It has superior wear resistance and scratch-proof capability, suitable for optical windows that face continuous friction, particle abrasion or heavy mechanical contact. For example, high-speed equipment observation windows, handheld measurement device front protective windows, or optical parts exposed to sand and dust impact will benefit greatly from sapphire material.

Besides hardness, sapphire features wide spectral transmission range, stable performance under high temperature and excellent resistance against acid, alkali and chemical erosion. It can keep stable optical property in high-temperature working environments and strong chemical corrosive atmosphere, where BK7 or fused silica may degrade. It is widely used for high-end sensor windows, military optical protection windows, high-temperature instrument viewports and medical invasive optical components.

However, sapphire has higher raw material cost and harder machining difficulty, which will increase component price and lead time. Our engineers will evaluate whether sapphire is necessary for your project. If your working condition does not need such extreme hardness, we will recommend fused silica, BK7 or aluminosilicate tempered glass as cost-effective alternatives to balance performance and budget. We supply custom-cut, polished and coated sapphire optical windows. We will compare material pros & cons and help you make the best substrate selection decision for your optical system.