The camera housing is designed to prevent dust from falling directly onto the sensor's protective glass surface. This is achieved by placing a piece of clear glass (monochrome camera models) or an IR cut-off filter (color models) that sits above the surface of the sensor's glass. A removable plastic retainer keeps this glass/filter system in place. By increasing the distance between the imaging surface and the location of the potential dust particles, the likelihood of interference from the dust (assuming non-collimated light) and the possibility of damage to the sensor during cleaning is reduced.

Warning! Cameras are sealed when they are shipped. To avoid contamination, seals should not be broken until cameras are ready for assembly on site.
Warning! Use caution when removing the protective glass or filter. Damage to any component of the optical path voids the Hardware Warranty. Removing the protective glass or filter alters the optical path of the camera, and may result in problems obtaining proper focus with your lens.
Related Knowledge Base Articles
Removing the IR filter from a color camera
Selecting a lens for your camera