Names of Sapphire Windows in Different Applications
Sapphire is a crystalline form of aluminum oxide characterized by its single-crystal structure. Due to its transparency after polishing, it is commonly referred to as sapphire glass. The term “sapphire window” encompasses both sapphire optical windows and sapphire protective windows.
- Sapphire optical windows
Sapphire optical windows are specifically designed for optical applications such as imaging, detection, and scanning. Given sapphire’s ability to transmit the full spectrum from ultraviolet to near-infrared light wavelength, these optical windows can significantly reduce the amount of glass required in optical instruments, thereby decreasing the overall weight of the device. However, the transmittance of sapphire typically ranges between 82% and 85%. To enhance or restrict the transmittance within specific wavelength, specialized coatings such as anti-reflective (AR) coatings and anti-fouling (AF) films are often applied to sapphire optical windows. High-intensity laser applications, in particular, have stringent requirements for such coatings.
In order to satisfy the elevated specifications of sapphire optical windows, the processing of these windows must also be subject to more exacting standards. In order to ensure the consistency of spectral transmission, it is necessary to ensure the parallelism of the sapphire windows. That is to say, the two sides of sapphire windows must be coordinated in order to solve the optical path problem. Additionally, the flatness (surface shape) of each window must be meticulously controlled at the nanometer level, typically requiring within 1/4 wavelength, as is referred to in optical terms.
- Sapphire protective windows
The utilization of sapphire protection windows, which are characterized by their resistance to pressure, abrasion and high temperatures, serves to provide a robust barrier for safeguarding the user or the contents within the sapphire containers. Sapphire is renowned for its high hardness, which endows it with superior resistance to pressure and abrasion when compared with other glass products. The utilization of protective windows processed with sapphire is frequently observed in a variety of settings, including deep water, oil fields, instances of flammability and explosivity, high pressure vessels, and vacuum vessels, among others. Concurrently, sapphire demonstrates remarkable resistance to high temperatures of up to 2030 degrees Celsius, a property that renders it particularly well-suited for application in high-temperature containers.
As demonstrated above, the term “sapphire windows” is a generic designation, whereas “sapphire optical windows” and “sapphire protection windows” are proprietary names that denote sapphire glass of distinct applications.
