Sapphire windows are made from synthetic sapphire, which is a single crystal form of aluminum oxide (Al2O3). Sapphire is highly regarded for its excellent optical properties, including high strength, hardness, and transparency across a broad spectrum of wavelengths from UV to IR. Here are the key optical components and properties of sapphire windows:
- Transparency: Sapphire is transparent from UV (around 200 nm) to IR (up to about 5-6 μm), making it suitable for a wide range of optical applications.
- Refractive Index: The refractive index of sapphire varies slightly with wavelength but is typically around 1.75 in the visible spectrum.
- Dispersion: Sapphire exhibits low dispersion, which means it does not separate different colors of light as much as other materials, leading to minimal chromatic aberration.
- Transmission: Sapphire windows can transmit up to 85-90% of light in the visible spectrum and even higher in the infrared region, depending on the thickness and surface quality.
- Surface Quality: Sapphire windows can be polished to extremely high surface qualities, with typical surface finishes of 10-5 or better.
- Mechanical Properties: Sapphire is extremely hard and scratch-resistant, making it ideal for harsh environments where durability is essential.
Sapphire windows find applications in various industries, including aerospace, military, medical devices, and high-power laser systems, where their optical and mechanical properties are highly beneficial.