The choice of the laser source is the most important question is systematic and integrity, the laser source and the camera, lens, protective cover, such as power supply complete sets of sex; And if the variable Angle laser source, the laser source variable Angle at night with the camera, the camera Angle changes automatically following the consistency. At the design of all equipment comprehensive consideration design, use it as an infrared low illumination night vision surveillance systems engineering to consider design. Many engineering, procurement of cameras, lenses, guard, even after the installation after the power supply to consider buying laser source, this is not correct, when considering systematic and integrity, paying special attention to the following questions.
1. The use of black and white video camera or special color video camera
CCD image sensor with photosensitive spectral range is very wide, not only including the visible light region, the photosensitive spectra has also extended to infrared area, using this feature, you can at night without visible light illumination, infrared light source with auxiliary lighting also can make the imaging of CCD image sensor is clear. And ordinary color video camera to transmit the color signals, isolated from CCD output signal of the device in green and blue and red three color video signal, and then synthetic colour TV signal, only the light spectra in the visible region. With the progress of technology in black and white color during the day/night cameras, it USES two CCD to switch or using a CCD digital circuit switch is used to implement, but there are black and white and high intensity of illumination, shortcomings and so on some adverse impacts on the chromatic colors. And infrared infrared sensitivity low illumination color video camera is a more than four times higher than average camera, with the reduction of the cost will be the development trend.
2. Request to choose low illumination cameras
The camera when your subject is the minimum illumination of scenery brightness low to a certain extent and make the camera output video signal level low brightness value to a specified value of things. The determination of the parameters, should also be noted the aperture of the lens the size of the F. Pro series of lenses, for example, when photography scene illumination value as low as 0.02 Lx, camera output video signal amplitude to a standard of value of 700 mv 50% – 50%, says the lowest illuminance of the camera is 0.02 Lx/pro series. Some different camera manufacturers give an F in minimum illumination. When choosing cameras minimum illumination than laser source, what is the range of laser source will be some impact. Should remind users is sold on the market of camera technical performance marked the lowest illuminance has two kinds of abnormal situation, one is the lowest illuminance is the so-called marked camera manufacturers target surface illumination, namely illuminance on the CCD image sensor, it is about 10 times lower than the scene illumination; Another kind is a few camera manufacturers or sellers about minimum illumination. Comparison on the market at present the economy (black and white camera price in 700 yuan or so, some minimum illuminance standard is 0.01 ~ 0.05 Lx) their actual minimum illuminance only 0.1 ~ 0.2 Lx, if, low intensity of illumination of laser source for the camera to the use of the 0.05 Lx, inevitably affect available irradiation range of laser source, and buy 0.05 Lux minimum illumination cameras, the price may be about 0.1 ~ 0.2 Lx cameras at least twice as high. There are two options at this moment, the camera photographic technology grasp strictly, on the laser source for optical imaging can save budget, also can achieve the best effect of night vision; Cost savings on the camera, waste cost on laser source, also not achieve expected effect of night vision. Experience suggests that outdoor especially distance is far, the former is more economical and practical.
3. Ask the size of the camera
Increasingly miniaturized camera nominal size, cameras on the market at present the dimensions with 1/2 “1/3” 1/4 “, the camera size is big, accept the luminous flux is big, the camera size, accept less luminous flux, such as laser source nominal effective distance is in 1/2 “under the condition of experiment, such as using a third” or 1/4 “camera, effective distance will also be affected by a certain, and a third” camera flux only 1/2 “camera luminous flux of 44%.
4. The functions of the camera and lens
Cameras have automatic electronic shutter function, AGC automatic gain control function, has automatic aperture lens, day and night to adapt to the great changes of illuminance.
5. The power supply
TV front-end equipment of the power supply to monitoring systems into consideration. The power supply of laser source, considering the working current of LD was highly sensitive to the power supply voltage, cable length and different attenuation of dc voltage. In multiple laser light when the distance from the control room is large, using DC12V power supply may be away from the control room near clustering of laser source high voltage, low voltage power supply from the control room far laser sources. Combined with the power supply voltage deviation on the adjustment, may cause high voltage source of the laser light the effect not beautiful or cause equipment damage. So as far as possible use AC220V power supply or one-to-one dc regulated power supply, the dc regulated power supply some in power grid voltage fluctuation in AC180V – 245 – v output dc voltage is stable, ensure the laser source radiation power is stable and reliable.
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