Top 5 Factors to Consider When Choosing Optical Windows

Optical windows need to be compatible with the systems they are being used within. As such, it is important for an optical window to be able to transmit the appropriate wavelength ranges. Different materials have different wavelength transmission capabilities. Therefore, it is very important to choose optical windows with material transmission properties that match those required by your application.

The refractive index of an optical window is a measurement of how quickly light passes through the material in question (or more accurately, how much light slows down as it passes through the optical window). This property can absolutely affect how well an optical window performs in a given role, so it is an important thing to take into account.

Knoop hardness is a measurement of how resistant glass is to indentation. Generally speaking, a material with a higher knoop hardness is less brittle. For applications that involve high pressure differentials, you will want to choose optical windows that have a high knoop hardness; if you do not, your optical windows may not hold up well.

The coefficient of thermal expansion is a number used to describe how much the size of glass changes based on exposure to different temperatures. This is an especially important factor to consider when choosing optical windows for applications that involve extreme temperatures in either direction, or quick and frequent temperature changes.

Surface specifications, like surface quality (the evaluation of a surface’s imperfections caused by manufacturing or handling) and surface flatness (the measurement of how much an optical window deviates from a perfectly flat surface), can affect how well an optical window performs, especially in applications that involve particularly sensitive surfaces. These factors should always be considered during the optical windows purchasing process.