Sapphire is a type of crystal with a single crystal arrangement structure of alumina. Due to the fact that sapphire becomes transparent after polishing, some people also refer to it as sapphire glass. Sapphire window plate is a common name that includes sapphire optical window and sapphire protective window.

1、 Sapphire optical window panel

Sapphire optical window plate refers to sapphire window plate products used for optical purposes, generally including imaging, detection, scanning, etc. Due to the full spectrum transmission capability of sapphire from ultraviolet to near-infrared, sapphire optical windows can reduce the amount of glass used in optical instruments and significantly reduce the weight of equipment. However, the transmittance of sapphire material is only between 82-85%. In order to increase the transmittance of specific bands or prevent the transmittance of specific bands, special coating treatments such as AR coating, AF film, etc. are often required for sapphire optical windows. In high-intensity laser applications, higher requirements are placed on coating.

In order to meet higher requirements for sapphire optical windows, higher demands have also been placed on the processing of sapphire optical windows. In order to ensure the consistency of spectral transmission, it is necessary to ensure the parallelism of the sapphire window (i.e., consistent coordination on both sides to solve the optical path problem); Secondly, there are strict requirements for the flatness (surface shape) of any plane, which is required to be within the nanometer range, known as wavelength in optical terminology, and generally within 1/4 wavelength.

2、 Sapphire protective window

Sapphire protective windows are window products that utilize the pressure resistance, scratch resistance, and high temperature resistance of sapphire to protect users or items inside containers. Due to the high hardness of sapphire, it has stronger pressure resistance and scratch resistance than other glass products. Sapphire processed protective windows are commonly used in deepwater, oil fields, flammable and explosive environments, high-pressure vessels, vacuum vessels, and other fields. Meanwhile, sapphire can withstand temperatures up to 2030 degrees Celsius and is commonly used in high-temperature container applications.

From the above, it can be seen that sapphire window is a generic name, while sapphire optical window and sapphire protective window are proprietary names for different applications of sapphire.