The “window” or transparent covering of an enclosure is usually made of high-quality glass or durable, polycarbonate plastic. As windows act like optical lenses, they should be of high quality to minimize its effect on image quality. When there are built-in imperfections in the clear material, clarity is compromised.
Higher demands are placed on the windows of housings for PTZ cameras and PTZ dome cameras. Not only do the windows have to be specially shaped in the form of a bubble, but they must also have high clarity since imperfections such as dirt particles can be magnified, particularly when cameras with high zoom factors are installed.
In addition, if the thickness of the window is uneven, a straight line may appear curved in the resulting image. A high-quality bubble should have very little impact on image quality, irrespective of the camera’s zoom level and lens position.
The thickness of a bubble can be increased to withstand heavy blows, but the thicker a covering is, the higher the chances of imperfections. Increased thickness may also create unwanted reflections and refraction of light. Therefore, thicker coverings should meet higher requirements if the effect on image quality is to be minimized.
A variety of dome coverings or bubbles are available, such as clear or smoked versions. While smoked versions enable a more discreet installation, they also act much like sunglasses do in reducing the amount of light available to the camera. It will, therefore, have an affect on the camera’s light sensitivity.