Optical Sapphire Windows

Swiss Jewel Co. offers online purchasing of a wide selection of competitively priced, standard optical windows from our online catalog. If you require a customization, coating or large volume pricing contact us at 800-922-0118.

Optical sapphire windows are precision components made from synthetic sapphire (Al₂O₃), known for their exceptional optical, mechanical, and thermal properties. These windows transmit light over a broad range of wavelengths, making them a popular choice for demanding environments and high-performance applications. They are highly valued for their unique combination of durability, thermal resistance, and broad optical transmission. These properties make them ideal for challenging applications across a range of industries, including aerospace, medical, industrial, and scientific fields. Additionally, the use of various optical coatings such as anti-reflection, infrared, hard carbon, laser-specific, and hydrophobic coatings further enhances their performance, making sapphire a top choice for optical systems in demanding environments.

Key Properties of Sapphire:

Optical Clarity: Sapphire windows have excellent optical transmission from the ultraviolet (UV) to mid-infrared (IR) wavelengths, typically from around 150 nm to 5.5 µm, providing clarity over a wide spectral range.

Hardness and Durability: Ranking 9 on the Mohs hardness scale, sapphire is second only to diamond. Its resistance to scratches, wear, and damage makes it ideal for harsh environments where durability is key.

Thermal Stability: Sapphire can withstand extreme temperatures, remaining stable and maintaining its optical integrity up to around 1800°C (3272°F).

Chemical Resistance: Sapphire is chemically inert, resistant to most acids and alkalis, making it suitable for corrosive environments without degradation.

Ideal Conditions for Sapphire Windows:

Sapphire is the ideal material for optical windows in conditions that require:

High temperature resistance: Suitable for high-temperature furnaces, aerospace environments, or any applications where thermal expansion and stability are critical.

Durability under mechanical stress: Ideal for high-wear environments, sapphire’s toughness ensures long-lasting performance.

Optical clarity across a wide spectrum: The ability to transmit UV, visible, and IR light makes sapphire optimal for optical instruments that require performance across multiple wavelengths.

Optical Coatings:

To enhance the performance of sapphire windows in specific applications, various optical coatings are applied. These coatings optimize transmission, reduce reflections, and protect the surface for extended use.

1. Anti-Reflection (AR) Coatings:

   AR coatings are applied to reduce surface reflections, increasing the efficiency of light transmission through the window. This is particularly important for applications requiring high levels of light transmission across a wide spectrum.

   AR coatings can achieve reflectance values of less than 0.50% over a typical wavelength range of 400-700 nm, making them essential for improving performance in visible-light applications.

2. Infrared (IR) Coatings:

   For IR-specific applications, coatings tailored to infrared wavelengths (e.g., 2-5 µm) can be applied, enhancing the sapphire window’s performance in mid-IR systems such as thermal imaging devices and IR spectroscopy.

Optical Sapphire Window Applications

Here are seven current and popular applications of optical, sapphire windows:

1. Military Applications: Sapphire windows are extensively used in military applications due to their robustness and optical clarity. They are integrated into military weapon systems, guidance systems, and for protection of sensors and imaging devices. The U.S. Air Force is funding projects to develop large-area sapphire windows for infrared (IR) sensing applications, highlighting the material’s importance in defense technology.
2. Aerospace: Sapphire windows are utilized in aerospace for their ability to withstand extreme temperatures, high pressures, and harsh environmental conditions. They are used in commercial and military aircraft to protect sensors and optical systems from fast-moving particulates and chemical exposure. Sapphire’s hardness and wide transmission range make it ideal for use in aircraft and drones.
3. Underwater Vehicles: High-pressure environments, such as those encountered by Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs), benefit from the durability and optical clarity of sapphire windows. These windows can withstand pressures up to 10,000 psi and resist algae growth, ensuring clear visibility and protection for imaging systems in underwater explorations
4. Medical Devices: In the medical field, sapphire windows are used in endoscopes and other diagnostic equipment due to their biocompatibility, scratch resistance, and ability to endure sterilization processes. Their optical clarity ensures precise imaging, which is critical for medical diagnostics and procedures.
5. Industrial and Environmental Monitoring: Sapphire windows are also used in industrial and environmental monitoring equipment. Their resistance to chemical corrosion, high temperatures, and abrasive environments makes them suitable for use in furnaces, gas and oil analysis devices, and other harsh industrial applications. They ensure long-term durability and accurate measurements in demanding conditions.
6. Consumer Electronics: Sapphire windows are used in consumer electronics, particularly in high-end watches, smartphones, and camera lenses. Their scratch resistance and optical clarity make them ideal for protecting screens and lenses, providing durability and improved user experience in everyday use.
7. Semiconductor: In the semiconductor industry, sapphire windows are used as substrates for growing high-quality epitaxial layers for LEDs, lasers, and other optoelectronic devices. The material’s excellent thermal and chemical stability, as well as its ability to be polished to an extremely smooth finish, make it suitable for these high-precision applications. Sapphire’s transparency across a wide wavelength range also makes it valuable for photolithography and inspection processes in semiconductor fabrication.