I. Overview <br> <br> in TV monitoring systems engineering, in the past few applications of infrared light, but because today's society not only increase the crime rate, infrared night vision surveillance played a more prominent role, not only the treasury, oil depots, armories It is adopted by important departments such as library, library of books, cultural relics, and prisons, and is also used in general surveillance systems. Even the residential area television monitoring project also uses infrared cameras. This shows that people's requirements for television monitoring system engineering become more and more standard and more and more. More and more important sites require 24-hour continuous monitoring.
The method of realizing night vision can use conventional visible light illumination, but this method not only cannot conceal, but also exposes the monitoring target even more. Covert night vision surveillance is currently using infrared camera technology. Infrared camera technology is divided into passive infrared camera technology and active infrared camera technology. PIR technology uses the principle of infrared emission from any object above absolute zero (-273°C). Since the human body and heat emitting objects emit strong infrared light, other non-heating objects emit weak red light. Therefore, night surveillance can be achieved using a special infrared camera. The passive infrared camera technology is not adopted in night vision systems due to high equipment cost and failure to reflect the surrounding environment. The active infrared camera technology uses specially designed "infrared lamps" to artificially generate infrared radiation, produce infrared light that is invisible to the human eye and can be captured by ordinary cameras, radiate "illumination" scenes and environments, use ordinary low-light-rate CCD black-and-white cameras or use "daylight The color nighttime camera that automatically turns black and white, or the "infrared low-illumination color camera," feels infrared light reflected from the surrounding environment to achieve night vision.
Second, the principle characteristic of the infrared camera <br> <br> light is an electromagnetic wave whose wavelength interval from a few nanometers (1nm = 10-9m) to 1 millimeter (mm) or so. What the human eye can see is only part of it. We call it visible light. The wavelength of visible light ranges from 380nm to 780nm. The wavelength of visible light is divided into red, orange, yellow, green, cyan, blue, and violet, and its wavelength is shorter than that of violet. Ultraviolet light is called infrared light, and its wavelength is longer than infrared light.
Infrared light according to its infrared light radiation mechanism is divided into semiconductor solid light (infrared emission diode) infrared light and heat radiation infrared light two. The infrared light of the infrared emitting diode is mainly used in the general market. Its principle and characteristics are described as follows: The light emitting body is composed of an infrared light emitting diode matrix. The infrared emitter diode is made of a material with high infrared radiation efficiency (usually gallium arsenide GaAs) made of PN junction, plus a forward bias to inject infrared current into the PN junction to stimulate infrared light. The spectral power distribution is center wavelength of 830-950 nm, and the half-peak bandwidth is about 40 nm. It is a narrow-band distribution, which is a range that a common CCD black-and-white camera can sense. Its greatest advantage is that it can be completely free of red storms (using infrared tubes at 940 to 950 nm wavelengths) or only weak red storms (red storms have visible red light) and long life. The emission power of infrared light emitting diodes is expressed in terms of irradiance μW/m2. In general, the infrared radiation power is proportional to the forward operating current, but near the maximum rated value of the forward current, the temperature of the device rises due to the heat dissipation of the current, and the optical emission power decreases. Infrared diode current is too small, it will affect the radiated power to play, but the operating current is too large will affect its life, and even make the infrared diode burned. To address this situation, Fujifilm Computer Co., Ltd. FI-930C and FI-970C have taken this issue into full consideration in designing. Using high-efficiency light-emitting diodes, a built-in heat-dissipation system is built into the camera to achieve a stable working time of 25,000 hours!
Third, selection and use of an infrared lamp <br> <br>
infrared camera selection
of the most important issue is the complete set of infrared light and the camera, lens, protective cover, the power supply and the like. At present, most cameras on the market are separate from infrared projectors. In this way, we must consider all equipment in the design of the project. Is it the choice of a black and white camera with an infrared lamp or a black and white camera with color? There are also considerations for installation and waterproofing. In general, the CCD sensor used in black-and-white cameras has a wide range of light-sensing spectrum. The light-sensing spectrum not only includes the visible light region, but also extends to the infrared region. Using the auxiliary infrared light illumination can clearly image the CCD sensor, and the ordinary color The camera's light-sensing spectrum is only in the visible light region, so it cannot be used for infrared light bulbs to illuminate the camera; day and night type cameras use two CCDs to switch or use a CCD sensor, and the switching of the digital circuit can also achieve infrared light bulb irradiation, but there is Black and white illuminance is high or there are disadvantages such as bad influence on color. In addition, there is an integrated infrared camera, which is a camera, lens, protective cover, infrared light, etc., together with typical products such as FU-Kang's FI-930C and FI-970C. High-quality aluminum shell, through a molding process, the product's waterproof rating to IP55 level, can be used in indoor and outdoor common, due to the use of integrated design, it naturally reduces the difficulty of construction and debugging.
With the rapid development of infrared night vision systems, infrared lamp production and supply manufacturers will also increase, but infrared products are not as easy as some people think, but also have different conditions in terms of technology, detection equipment, and so on. We hope that users will make more comparisons. Choose carefully.
Users should first read the instruction manual carefully when using the infrared light, especially the precautions for ensuring personal equipment safety. Check whether the supporting aspects mentioned in the previous section meet the requirements. Whether the influencing factors that should be taken into consideration should be taken into consideration, if not meet the requirements, the equipment used can be adjusted in time.
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