Sapphire Optical Shapes: Domes, Lens, and their Uses

Synthetic sapphire is the hardest of all known oxide crystals, with a Mohs hardness of 9. The hardness of man-made sapphire is second only to diamond, and it still maintains its robust mechanical properties and integrity at high temperatures.

The synthetic process of sapphire creation, though is a bit complex, nevertheless, several optical shapes such as thin sheets, sapphire domes, and lenses are produced today. Synthetic sapphire has many robust mechanical, chemical, and optical properties that make it an ideal choice for several situations. Sapphire can be thus used in cases where there is a need to protect delicate instruments from severe environmental conditions.

Properties of Sapphire

The synthetic sapphire crystal has good thermal properties and excellent electrical and dielectric properties. In addition, synthetic sapphire combines zero porosity with almost total resistance to acids and alkalis. It is insoluble in watches and can only react with hydrofluoric acid, phosphoric acid, and potassium hydroxide at high temperatures above 300 degrees Celsius.

Synthetic sapphire is an anisotropic hexagonal crystal. Its properties depend on the crystallographic direction (relative to the optical axis C).

Monocrystalline Sapphire Al2O3, as mentioned, has a unique combination of excellent optical, physical and chemical properties. Sapphire Al2O3 is the hardest oxide crystal, it still maintains its high resistance to high temperatures, has good thermal properties and excellent transparency.

Sapphire Al2O3 optical elements are chemically resistant to a variety of acids and alkalis at temperatures up to 1000 degrees Celsius and HF below 300 degrees Celsius. These characteristics make it widely use Al2O3 sapphire optical elements in harsh environments. Its optical transmission range is spread out from the visible light range to near-infrared, so it can be sued in situations where it is required to have a material with a good transmission range.

How is Sapphire Produced?

Today, most crystals are grown from molten liquids. The most suitable substance for growing crystals from a melt must be melted without decomposition, where there is no polymorphic transformation, and the chemical activity is low. The melt crystallization process is applied to the most widely used monocrystalline sapphire growth methods: the horizontally oriented crystallization (HDC) method and the Stepanov method.

The Stepanov method is used to cultivate monocrystalline sapphire of various structures, such as sapphire domes, lens, and the horizontally oriented crystallization method is widely used to synthesize largely sapphire single crystals.

The crystal grows in a local melting zone with a furnace and moves slowly along the vessel, and is shaped like a boat. The horizontally oriented crystallization method can accommodate sapphire single crystals with small cross-sections and sparse sizes, and allows sapphire single crystals to grow into record size plates, which cannot be achieved with other methods.

Sapphire is used in large aperture windows, viewfinder and illuminator, and in general aperture optical systems (visible light + infrared).

Sapphire products are used as optical components in many fields (windows, flat plates, light guide plates and lenses). Sapphire and other materials can easily be used together to make sapphire domes of any shape and size.

Features & Applications of Sapphire Domes

Sapphire domes are superior to other types of substrate materials and products. In harsh environments where wide viewing angles are needed, sapphire domes allow placing sensors or cameras inside to view and monitor the activities going around. It offers a durable and strong protective environment for housing other optical applications or components.

If you compare sapphire domes with any glass domes having the same thickness, the former excels in terms of incredible strength and excellent scratch resistance properties.

Sapphire domes possess high transmittance, hardness, resistance to abrasion, thermal shock resistance, etc., which makes them ideal for several industrial applications. They are used in high-pressure systems, semiconductors, oil platform inspection, marine products, plasma & chemical processing, and many other applications.