The importance of choicing Infrared Illuminator is the compatibility
of the camera and illuminator, lens, cover, power supply etc. In the
design of programmes for the integrated system, the engineer should
considered to design the whole sets of equipment as a low intensity
infrared night vision surveillance systems. It is incorret for people who
first buy cameras, lens, covers, power supply and even install them before
purchase the infrared illuminator, People should pay attention to the
1.Use black and white cameras, color cameras or special transformed
ordinary colour cameras
CCD image sensors have very wide spectral range photosensitive, the
photosensitive spectrum includes not only the visible area, but also
extended to the infrared area. To use this feature, the camera could be
use under invisible conditions at night, and the infrared illuminator
will support the CCD image sensor to get clear image. Ordinary colour
cameras can transmit colour signal from the CCD output signal devices
separate from the three green-blue-red base color video signals, and then
synthetic colour television signals. The photosensitive can only be
installed in the visible spectral region, if it is possible to achieve the
transformation of its infrared light region sensory functions through its
CCD infrared filtering glass, the front infrared can penetrate into the
850nm infrared filtering glass or without infrared filtering glass.
(attention! Without infrared filtering glass color change may lead to
With the advances of technology, the current market colour day and
night conversion camera is used a cut-over two CCD or a CCD digital
circuits used for the cut over, but the existence of black and white
illumination is higher, some of the shortcomings effects of colour will
gradually be eliminated. The infrared sensitive of Low intensity colour
and infrared camera is four times higher than normal camera. With the
tend of lower costs, it will become the trend.
2. To select an 850nm infrared camera with low intensity respondent
Low intensity means that the optical brightness degree when the light
of sence and the video signal output electricity balance of the camera
reach a special low range. To measure the parameters should specified the
size of the camera's aperture F. For example, using a F1.2 lens when the
illumination is 0.02Lux, the scope of the video camera output signal is
50%-33% of the standard scope 700mv, we say that the camera with the low
illuminance of 0.02Lx/F1.2. Some camera manufacturers give different
aperture F, the lowest illuminance. When the low illuminance of the camera
is higher than infrared illuminator requested, the effective distance
infrared lights will be affected. Users should be reminded that the sale
of camera technology in market marked the low illuminance with two
unnormal ways, one is that the camera manufacturers marked the low
illuminance target surface, which is the illuminance of CCD image sensor,
and it features with low illumination more than 10 times more than the
scenery; Another one is the false illuminance quoted by some camera
manufacturers or distributor. Currently, some economical black and white
video cameras have the low illuminance of 0.01~0.02Lx, but in fact
0.1~0.2Lx only. If the infrared illuminator require a camera with 0.02Lx,
it will affect the effective irradiation distance, and purchase a 0.02Lux
camera will need twice cost of a 0.1~0.2Lx cameras. In this case there are
two options, to spend more money in camera, but less in infrared
illuminator; or on the contrary. Experimental verification that the former
option is more economical for outdoor long distance.
3.The size and specifications of CCD camera
The size of a CCD camera is becoming smaller, and in the current
market there are 1/2 ", 1/3 ", 1/4 " CCD cameras. The bigger size of the
camera, the more transmition of light. For example, the effective infrared
lights distance is tested with the 1/2 " CCD camera, if you use 1/3 " CCD
or 1/4 " CCD camera, the distance will be effective. The light transmition
of 1/3 " CCD camera is only 44% of the 1/2 "CCD camera. Choose colour
black and white clock automatic conversion should particular paying
attention to the selection of the camera with 1/3 " CCD, because tmost
camera in the market is with 1/4" CCD.
4. Selection of lens
The smaller of the aperture F of the lens, the greater the effects
footage - ray hole.
5. The required functions of cameras and lens
With automatic electronic shutter function, AGC functions, and
automatic aperture of the lens, the cameras can accommodate large range of
illuminance changes in day and night.
6. Power supply
Fronter video survaliance system equipment should be integrated into
the power supply design. The working current of the infrared illuminator
is sensitive with the power supply voltage and different length of cables
determined different decay of DC voltage. When you are using a number of
infrared light with various distance between the control room, a focus
power supply of DC12V may cause a high voltage of the infrared illuminator
whichi is near the control room and low voltage which is far away from the
control room. In addtion, the deviation of adjusting supply voltage will
cause over high voltage and the life time of infrared illuminator will
shorten or burn off; low voltage infrared illuminator will find power
shortage. It is proposed that adapt a AC22V supply or a one to one DC
voltage power supply. This kind of DC supply has stable output of current
in some DC voltage power net or voltage fluctuations with a voltage
stabiization of AC100V-245V to assure the reliable and stable power of
the radiation of infrared illuminator.
In addition, please take into account the following factors, to choice
a good distance of radiation of infrared illuminator.
1.The low intensity of the cameras. What is the lowest intensity mean
here? The video signal value of camera is 1V, the standard value is 0.7V ,
and the video signal value of lowest intensity is 1/3-1/2 of the standards
for planting. In this case, camera cannot see as in bright day light under
a lowest intensity situation.
2.The image horizontal of Camera under the lowest intensity situation
is examed by the measure cark of video signal, the black and white
alternate with the code for black reflectivity is near 0%, 89.9% more than
the rate of white reflection. But in fact we do not have such conditions,
such as : the reflection rate and contrast of leaves and grass is low, we
cannot have a clear image.
3.Low intensity is given by the camera while also providing relative
value of F requirements. The zoon lens generally be with a maximum
photography 1:F only, which is the minimum at aperture F (f actual size of
the apetrure), F=f/D, if D for the constant vatio, when f focal length
widen 10 times, F is becoming big (f actual size becomes small).
Transmition of light will be greatly affected.
4.In the use of automatic aperture lens, AGC or automatic electronic
shutter camera, the aperture F of lens will be changed. For example, there
are features near the camera, reflecting llight back to the camera glare,
or light exposures the cameras, this camera's sensitivity will be reduced
at that time and the automatic aperture size will become small,
transmition of light will be greatly affected. Therefore, the application
shall be automatically fitted accurately adjust its automatic current
balance, DC automatic control mode in the camera's lens aperture scale
resistance video automatic control mode, aperture lens adjustment.
5.Defensive cover also have an impact on the effectiveness of infrared
illuminator. Infrared light transmit through different media,
transmissivity and reflectivity are also different. Different window
glass, especially automatic defrost coated glass, will attenuate the
infrared radiation, so they should choose the Windows layer glass.
6.Some manufacturer and distributor giving power only without infrared
lights irradiated distance which is a very vague concept. Beside the power
consumption that transfer into the infrared light energy, there are losses
of heat and power, circuit, light source, infrared light filtering glass
efficiency, and so on. The same power infrared illuminator, the radiation
distance may be great different.
With the rapid development of infrared night vision systems, the
number of infrared illuminator suppliers will increase, but this kind of
products are not be produced as easy as people imaging. The technology,
instrumentation of facilities conditions are vary from them, so I hope the
buyer and user can compare these, choose your need and want professinally.
To use infrared illuminator firstly is to read the user mannual
carefully, especially to ensure the personal safety equipment attention
matters. Inspection the point I told previously such as the compatibility
and the interfering impact of factors.
Users should not arbitrarily increase supply voltage, Infrared
illuminator is designed to considered the full play of their irradiance
and its security reliability. Increase supply voltage, may burn out the
it. Also arbitrarily break up is not allow. If so, the manufacturers may
not be responsible for maintenance. If infrared light problems you should
contact with the manufacturers or supplier first.