Understanding Infra Red Lamps
The range that your camera will see in the dark will depend on the sensitivity and spectral response of the camera and lens combination. Some cameras have a better IR performance than others. For maximum performance choose IR sensitive cameras.
The human eye cannot see infra-red light, however most mono CCTV cameras can. As such the invisible light can be used to illuminate a scene, this allows night time surveillance without the need for additional artificial lighting. Infra-red also provides many other benefits above conventional lighting. The infra-red beam shape can be designed to optimise CCTV camera performance, as such it is important to remember to design illumination for the CCTV camera and scheme.
Infra-red lamps cannot work with colour cameras. Normal artificial light e.g. sodium light, causes problems to the quality of the picture, not producing accurate colour quality. There are two options: It is possible to use a mirrored shift filter lamp that produces good colour rendition with a good quality low-light colour camera or to use a dual technology camera (colour by day, monochrome at night) together with IR lamps.
Bulb life is dependent on filament ruggedness, design and power management and control. Standard IR lamps claim average life between 2,000 to 5,000 hours. Choose lamps with long average bulb life to reduce maintenance costs. For short-range, low power applications consider LED products with a greater than 5-year life.
Infra-red lamps come in varying wavelengths from approx. 730nm to 950nm. 730nm filters are overt and give a red glow - like a traffic light. 830nm filters are semi-discreet and produce a dull red glow. 950nm filters are effectively totally covert - giving off no visible illumination. Viewing distances are reduced with 830nm and 950nm lamps. A 950nm will require a highly sensitive night time camera.
This article was supplied by Norbain and used with permission. Norbain are manufacturers of the Vista Protos range of state-of-the-art products designed for leading edge and performance critical applications - where extensive features and functionality are key.