Domes and Infrared Illumination
Infrared illumination is an essential requirement for effective nighttime surveillance. The traditional pan and tilt approach to mounting infrared illuminators offers the distinct advantage of permitting the infrared beams to follow the movement of the camera. Despite their flexibility and aesthetic appeal this is not possible with fully functional dome cameras.
Basic Solution: Fixed Domes
Dome cameras can be divided into two categories, fixed domes and fully functional domes. Fixed domes are often vandal resistant and used for short-range surveillance purposes. Because the unit is fixed the low light issues are similar to those of other standard cameras. In low light, or zero lux conditions, fixed domes will require additional lighting. Typically, infrared provides the best, most practical and cost effective solution.
To ensure full coverage of the scene, the infrared illumination must be matched to the field of view of the camera/lens combination. Narrow beam illumination should be used to match a narrow field of camera view and wide beam illumination should be selected to match a wide field of view. Failure o match the camera field of view and the infrared beam can dramatically reduce system performance.
Many dome systems have optional “smoked” domes that can reduce the infrared illumination that reaches the camera by as much as 70%. When smoked domes are employed increased infrared illumination levels may be required to compensate for the infrared attenuation of the dome.
Advanced Solutions: Fully Functional Domes
The main challenge with a fully functional dome is the inability to mount infrared illuminators on the moving part of the dome. To overcome these problem mounting bracketry has been developed which fits around the dome pole and makes it simple to install infrared illuminators.
Wide Angle Lighting
Achieving 360° degree lighting for Domes has traditionally been very expensive, requiring multiple illuminators. However, Raytec have recently launched a series of wide angle illuminators purpose designed for fully functional Domes. The new wide angle illuminators are available in Raymax (Infra-Red) and Raylux (White-Light) variations and are fitted with Adaptive Illumination providing vari-focal lighting. Adaptive Illumination is a new concept introduced and patented by Raytec allowing the installer to adjust the horizontal beam angle on site to match the specific needs of the installation.
Specialist wide angle illuminators provide 120 to 180° degree illumination meaning it is now possible to illuminate up to 360 degrees at significantly less cost and with less installation effort than ever before using only 2 illuminators.
Wide angle illumination is technically the best solution to Dome illumination providing purpose designed, even illumination fitted at the camera.