Ghid sisteme de supraveghere - Iluminarea IR pentru sisteme de supraveghere

IR illuminator: Redbeam IR40 (850nm, 60deg)
In order to prevent night-time burglaries and other crimes under cover of darkness, professional monitoring systems have to ensure 24/7 performance. It requires basic understanding of lighting issues.
What exactly is light?
Light is energy in the form of electromagnetic radiation. The human eye can see electromagnetic radiation in the wavelength range from 380 to 780 nm. CCTV cameras, in addition to the visible light, can detect infrared spectrum up to about 970 nm.
Whether we speak of the retina of the eye or the CCD (CMOS) sensor of a camera - the initial step of forming the image is the conversion of the information carried by light into electrical signals. The beams of the light reflected from various objects provide information about their shapes. Different wavelengths of "white" light (containing more or less the whole visible spectrum) are absorbed/reflected in varying degrees by the surfaces of the objects, which is interpreted by the human eye as differing colors.
The amount of the reflected light, and thus the efficiency of lighting, depends largely on the type of the illuminated objects and their surroundings. For example, infrared illuminators provide much better results indoors.
The perceived color of an object is dependent on both the features of the object and the type of lighting. For example, a "green" object reflects wavelengths corresponding to green color, and absorbs other wavelengths. Illuminated with "white" light, it is green, but in red light it seems black.
The physical quantity that is the best measure of light for CCTV applications is its intensity, called illuminance. It measures the brightness of a surface in a given point (luminous flux per unit area). The SI unit of illuminance is lux [lx]. Illumination meters (luxmeters) are well known from applications in professional photography.
The table below shows some values ​​with references to the natural environment.
Examples - surfaces illuminated by:
0.0001 Overcast sky at night
0.002 Moonless clear night sky
0.01 Quarter moon on a clear sky at night
0.27  Full moon on a clear sky at night
1 Full moon overhead in the inter-tropical zone
on a clear sky at night
100 Very dark overcast sky during the day
400 Sunrise or sunset on a clear sky
10000-25000 Clear sky at noon (in a shaded area)
32000-120000 Direct sunlight at noon
How to handle low light conditions?
When the light is insufficient to create a useful image, there must be used additional lighting. It can be provided by:
  • traditional lighting - visible light (lamps, floodlights)
  • infrared lighting - infrared light (IR illuminators)
Traditional lighting. Good traditional lighting based on incandescent or fluorescent lamps allows for capturing clear, color images. However, it is visible, so it may be easy for an intruder to avoid the illuminated zones. It is also expensive, requiring considerable amounts of energy and frequent maintenance.
Infrared lighting is generated by IR illuminators operating in the near infrared range, i.e. 700-1000 nm. With increasing wavelength, the light of a glowing lamp or IR LED is less visible to the human eye. Infrared illuminators have built-in filters: 750 nm (visible glowing), 830 nm (almost invisible glowing), 940 nm (completely invisible to the human eye).
Infrared illuminators allow for the creation of discrete monitoring systems with low operating costs.
What do cameras "see" in infrared?
Infrared radiation does not carry enough information about color, so the CCTV cameras normally switch to black and white mode. An important parameter of cameras operating in IR range is their sensitivity at the wavelengths generated by IR illuminators. An example of the relationship between the wavelength and cameras' sensitivity is shown below:
The graph shows that typical image sensors have poor sensitivity at wavelengths above 700 nm, and it falls dramatically at wavelengths exceeding 900 nm. Modern image sensors provide much better results in the IR range. The example is the Exview line with at least doubled sensitivity, which makes the cooperation with IR illuminators much more effective.
Aside from the suitable sensors, cameras intended for operation at longer wavelengths should be equipped with IR-corrected lenses, e.g. M2315, M23135, M2311, M2136, M2139. The application of IR-corrected lens eliminates focus problems when the camera changes its operation mode from color to black & white and vice versa. As usual, low F numbers will ensure higher sensitivity.
Operating distance of IR illuminators
IR illuminator range (aside from the output power and sensitivity of the camera) depends on the type of illuminated objects/surfaces (their reflectance in the infrared spectrum). It determines the intensity of the reflected light that can be captured by the camera. The table below shows approximate values of this coefficient for various surfaces/materials.

Surface/material Relative reflectance
Snow/white paper sheet
Window pane
Concrete 50%
Light color wood 45%
Packed parking lot
Park, trees 20%
Empty parking lot (asphalt)/black paper sheet 5%
Considering the power of IR illuminators needed for sufficient lighting of the monitored area, one needs to remember that the light intensity decreases inversely to the square of the distance from the source.
For example, it means that if an object at a distance of 10 m from the light source shows 90 lx , after moving it to a distance of 30 m it will show only 10 lx (tripled distance means nine times lower illuminance).
Cameras with lenses with a wide angle of view need adequate IR illuminators with similar or wider angle of radiation, such as Redbeam IR40 M1640 (total operational angle of 60o, range of 30 m).
In accordance with the described above relation, the range can be doubled by using 4 such illuminators (preserving the same direction/angle).
Modern IR illuminators with IR LED arrays - RedBeam series
Redbeam IR illuminators awarded Gold Medal at Securex 2010!
The advantage of the Redbeam series is application of specially designed LED array (instead of a conventional set of diodes) which, together with optical lens/es, ensures desired operational angle and distance.
The LED array used in Redbeam illuminators
View of the lens assembly in IR80 illuminator
Comparison of the IR LED array with standard IR LEDs
To make an IR illuminator of the same power, one would have to use a large number of typical IR LEDs and its size would be much greater. For example, an 1500 mW illuminator should consist of 100 LEDs of 15 mW output power. Of course, such a solution is feasible, but the illuminator would be much bigger than a similar Redbeam device.

Redbeam illuminators light the scene uniformly
The array of small size makes it easy to shape the beam with lenses. In the case of a traditional IR LED illuminator, the angle of the beam depends on the arrangement of LEDs, which is not a flexible solution. Using this LED array, virtually any angle can be achieved. The examples are the dome models M1642 and M1643, with beams of 180o.
Another advantage of the arrays is the lifetime of the materials used. Standard heavy-duty IR diodes operate around 6000 hours. In the case of the arrays, the expected lifetime is about 50000 hours. It means that they can work for over 10 years (12/24 cycle)!
Depending on the installation point and area of operation, one can distinguish two types of illuminators: directional (spot) and omnidirectional (180-degree in vertical plane and 360-degree in horizontal plane). The both types are available in 1800 mW and 3000 mW versions. The first type is mounted next to the camera and features a narrow beam, so the range of operation is 40 m and 80 m respectively. The second type (360-degree infrared LED dome illuminator) is mounted on a ceiling. Instead of the range, it is better to describe its capacity by the maximum surface that can be effectively illuminated - 60 m2 or 120 m2.
An IR illuminator installed next to the camera (not integrated with it) has the advantage over compact solutions that it does not overexpose objects appearing directly in front of the camera lens. It does not create problems with snow, rain, insects etc. in close foreground.
Redbeam - IR illuminators
A practical test of RedBeam illuminators
Test of Redbeam illuminators cooperating with CCTV cameras with 0.3 lx and 0.03 lx sensitivity. The following devices were used:
  • BOX camera Sunell SN-BXC5930CDN (day/night, 650 TVL, Sony Effio-E, 0.03 lx, WDR) - M11209,
  • BOX camera Sunell SN-BXC0483 (day/night, 450 TVL, Sony CCD, 0.3 lx) - M11212,
  • IR illuminator Redbeam IR40 M1640 with range of 30 m
  • IR illuminator Redbeam IR100 M1647 with range of 90 m
Click on a picture to enlarge it
SN-BXC0483 (the image on the left) was 10 times less sensitive and did not provide usable results
The range of the IR40 illuminator exceeded the rated 30 meters
The IR100 illuminator efficiently illuminated the whole scene,
the man's figure became visible from a distance of about 60 m
The tests show that the actual range of an IR illuminator is highly dependent on the sensitivity of the camera used. The visual observations were confirmed by the video motion detection of ULTIMAX-104 M71040 DVR that, with the more sensitive camera, detected the moving man at a distance of 60 meters, while in the case of the second camera it was only possible at a distance of 20 meters. Generally, more powerful lighting of the scene and application of a less sensitive camera may provide similar results to those with a weaker illuminator and a more sensitive camera.
Illuminators integrated with cameras (IR LEDs in compact cameras)
Besides typical IR illuminators, there are also many combined solutions. It can be an integral part of a camera or lens. Such solutions are very practical, because they reduce the number of additional elements and, additionally, lower the installation costs. The range of such an illuminator depends on its power, the number of IR LEDs and their arrangement (directivity).
Ceiling Dome Camera: CAM 622 (600 TVL, Sony Super HAD II CCD, 0.1 lx, 3.6mm) - CLEARANCE SALE!
Color CCTV Camera n-cam 225 with IR Illuminator
Color CCTV Camera n-cam 225 with IR Illuminator
Color CCTV Camera: U-cam 110 (box, 420 TVL, Sony Super HAD CCD, 0.8 lx)
Color CCTV Camera: U-cam 110 (box, 420 TVL, Sony Super HAD CCD, 0.8 lx)
Compact cameras can be divided into cameras without IR cut filters and cameras with removable IR cut filters (ICR). The cameras of the second type are more expensive because of the cost of the servo, but the image quality is much better, especially more accurate color reproduction and white balance (most noticeable at dawn and dusk).