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In the environment of infrared radiation, due to the absorption of the atmosphere, infrared radiation will be a certain amount of attenuation. When it is close to the ground, water vapor and carbon dioxide will absorb a certain amount of infrared radiation. Most thermal imaging cameras do not use compensation in the above situations. Therefore, in order to reduce the error, the infrared camera should be selected in an environment where there is no rain, no haze, and a relative humidity of 75% or less. Go on.
Under intense sunlight or intense illumination, due to the emission and diffuse reflection of light, the thermal imaging camera is greatly affected by these reflected rays and cannot make correct measurements. At the same time, the irradiation of strong light causes the temperature of the measured object to rise, and the temperature of the measured object itself is added, and the detected temperature is higher than the correct temperature of the measured object. Therefore, the thermal imaging camera should be protected from strong light to illuminate the object to be measured and the instrument itself, preferably in cloudy or cloudy weather or at night without intense illumination.
If the measured object is continuously blown by the wind, the airflow will take away the heat of the measured object, accelerate the heat dissipation of the surface of the measured object, and lower the surface temperature of the measured object, and the emitted infrared rays are weakened. At this point, the data detected by the thermal imaging camera will be lower than the correct temperature. In order to ensure the accuracy of the measurement, the thermal imaging camera should be operated in a windless or windy environment.
Dust and suspended particles are another factor that affects the operation of thermal imaging cameras. When the infrared rays emitted by the measured object pass through the dust or suspended particles in the atmosphere, the transmitted energy will be weakened, and the obtained data will be less than the normal value, which greatly affects the absorption of the infrared camera. Therefore, the thermal imaging camera should work in a clean and clean environment.
Objects around the object under test will affect the operation of the thermal imaging camera. As long as the object above absolute zero emits infrared rays, the higher the temperature of the object around the object, the larger the infrared rays emitted, the greater the influence. The lower the temperature of the surrounding objects, the smaller the infrared rays emitted, and the influence The smaller it is. Therefore, if the heat source around the object is high or high, the infrared camera should select the appropriate measurement angle or take measures to shield the surrounding environment to eliminate interference and measure the correct temperature.
Infrared camera products have many advantages and performance characteristics, and they play different roles in various fields. Because of the many performance and functional advantages of the products, today we will see if there is a huge breakthrough in the security of thermal imaging products. .
The true “infrared camera” is increasingly used in the non-military sector. The decisive factor is that the actual scene may be completely dark, while the thermal imaging camera records infrared radiation from the object itself. The instrument also penetrates smoke or fog, a unique advantage that helps rescuers on land or on the high seas to conduct personnel search and rescue operations. With the help of thermal imaging cameras, the fire brigade and the marine rescue department have saved countless lives. .
Six advantages of infrared camera:
1. Objects or personnel can be detected under dark conditions.
2, able to “see” the scene without lighting, so you can guard against intruders.
3. Detection through dense fog or smoke on land or at sea.
4. Personnel and on-site monitoring.
5. Security monitoring in key areas.
6, in the dark and dense fog environment, can rescue the victims.
A new generation of security surveillance infrared camera products with different advantages and performance, it is also known as passive infrared imager. Any object emits infrared rays that are invisible to the eye. Infrared cameras use this type of ray to form an image. The principle is similar to that of visible light imaging, but the difference is in the material of the lens and sensor.
Infrared cameras have advantages over ordinary visible light cameras:
1, in the absence of light, can be imaged, the effect is basically not affected by light.
2. In the case of a thick smoke screen, the target can be detected with little impact.
3. The ability to overcome rain, snow and fog is high, and the target can be observed from a distance.
Therefore, the infrared camera in the security field is a very effective device. The application field is very extensive and is often used to:
There are many things that need to be done in security work. Some advanced technology products, such as thermal imaging cameras, are used. The applications include fire monitoring, camouflage and concealed target identification, and security patrols at night and in harsh weather conditions. , key departments, construction, warehouse security, fire monitoring, onshore and port traffic security, airport monitoring, inspection and quarantine body temperature monitoring and other fields.
With a distance of several kilometers, it is ideal for border patrols, violent defense, night reconnaissance, industrial security, equipment security, dock port security, commercial security and other fields.
No need to launch any light, with concealed ability, can be installed in airport security monitoring, civil aviation facilities, important administrative centers, bank treasury, confidential rooms, military sites, prisons, cultural relics, guns and ammunition depots, dangerous goods warehouses, etc. place.
Explosion-proof infrared camera installation position to avoid glare (such as sunlight, lighting, etc.), otherwise it will easily cause excessive light or light (not fault), it will also affect the life of CCD; in addition, infrared has the same reflection as visible light Characteristics such as refraction, so there should be a certain distance margin when there is no good reflective environment around the target scene (such as buildings, fences, signs); the transmittance and reflectivity of different media are different, so different protective glasses, especially It is a glass with an automatic defrost coating layer, which will cause certain attenuation of infrared light, and special care must be taken during construction.
Explosion-proof infrared cameras should be protected from humid, dusty, extremely hot, extremely cold, and strong electromagnetic radiation. Rain, fog, dust and other climatic conditions are factors that restrict the distance of infrared light irradiation. In addition, the difference between the on-site environment and the reflectance of the monitored target will also make the night vision effect very different, so it is necessary to install the explosion-proof infrared before installation. The camera is tested.
Thermal imaging monitoring also performs well in other areas. For example, forest fire prevention. In addition to nighttime use as a field monitor, infrared thermal imaging provides preventive work for fire detection by reflecting the surface temperature of the object. Infrared thermal imaging can quickly and effectively detect smoldering fires and accurately determine the location and extent of fires.
There are more and more brands of explosion-proof infrared cameras. However, the conditions for the factory inspection, technology, testing equipment and other related products are not the same. Users should choose more explosion-proof infrared cameras. The explosion-proof infrared cameras on the market mostly use two infrared bands of 850nm and 940nm, and the infrared band of 850nm is more stable. In addition, users should choose an explosion-proof infrared camera with electronic control switching device, and its fuzzy logic ability can effectively control ICR- The working state of the CUT filter can make the infrared fill light more stable. Some manufacturers’ infrared lamps of explosion-proof infrared cameras have no irradiation distance parameters, only the number of powers. This is a very vague concept, because power consumption is not only converted into infrared light energy, but also includes power supply heat loss, circuit heat loss, and light source heat loss. , filter glass sheet infrared light efficiency and so on.
Infrared thermal imaging camera is an infrared thermal imaging instrument. It was mainly used in the military field at the earliest. Nowadays, with the development and progress of society, it has also been widely used in the development of civil industrial enterprises. In the production and work of people so widely, then, the thermal imaging camera must have its own unique advantages,
First, as an instrument for measuring temperature, it can visually display the temperature field on the surface of the object. It can simultaneously measure and display the temperature of each point on the surface of the object. In addition, it will be displayed in the form of an image, which makes us more intuitive and can be seen at a glance. This is the basis of the infrared camera as a high-tech image. Some have the biggest advantage.
Second, the resolution of the temperature is relatively high. Some thermometers are difficult to distinguish a particularly small temperature difference for various reasons, but the infrared camera can simultaneously display the temperature values of two points, so that the temperature can be accurately distinguished. The difference, this device with higher temperature resolution must be loved and trusted by the public.
Third, the collected information can be displayed in different ways. The infrared camera can collect a large amount of information when measuring the target, and display it in different ways. It can also perform some necessary color processing and graph on the information. The conversion of text and sound to achieve various desired effects.
Fourth, the infrared camera can perform data storage and computer processing. When the infrared camera is outputting video information, it can be stored in a digital memory or recorded by a video tape, so that not only can the data be stored for a long time, You can also use the computer to do some of the necessary processing of the stored data. This is undoubtedly a huge improvement over other simple temperature measuring instruments.
The correct name for the filter on the surveillance camera CCD is called “optical low-pass filter”
The filter has two functions: 1. Filter out the infrared light. 2. Trim the incoming light.
1. Filter out the infrared:
The surveillance camera color CCD can also sense infrared light, because it will induce infrared rays, which will cause the DSP to not calculate the correct color. Therefore, a filter must be added to separate the infrared part of the light, so only the color CCD needs to be equipped with a filter. Black and white will not be used.
2. Finishing the light:
Because the CCD is composed of a single photoreceptor (CELL), it is best to direct the light, but in order to avoid interference with the adjacent photoreceptor, the light needs to be trimmed, so the filter is not glass, but quartz. The film, using the physical polarization characteristics of quartz, keeps the incoming light, retains the direct part, and reflects off the oblique part to avoid affecting the photosensitive spot next to it.
So how do the filters do this?
1 Filter out the infrared:
The coating method and the blue glass can be used, and the coating is divided into a vacuum coating method and an electroless plating method. The electroless plating method is to immerse the quartz sheet in a solvent for electroplating, the cost is low, but the coating thickness is uneven and easy to fall off, and the vacuum coating is vacuum evaporation, and the coating is uniform. It is not easy to fall off, but the cost is high. Above we call IR Coating, the purpose is to filter out the infrared rays, and also add the so-called AR-Coating coating, the purpose is to increase the light transmittance, because the light is transmitted through different media (such as From the air into the quartz plate), part of the refraction and reflection will be produced. After AR-Coating, the filter can achieve a penetration rate of 98-99%, otherwise it will only have a transmittance of 90-95. Sensitivity certainly has an effect.
In addition, it uses blue glass. Blue glass filters infrared rays by means of “absorption”. IR-Coating filters out infrared rays by reflection, but reflected light is easy to cause interference. If only infrared rays are filtered out, blue glass is better. The choice. But the above said that the glass can not trim the light, so there is a so-called “two-piece” filter with a piece of blue glass and a piece of quartz. The blue glass is used to filter the infrared rays, and the quartz piece is used to trim the light, so the quartz Just do AR-Coating on the chip.
2. Trimming the light:
As mentioned above, using the physical polarization characteristics of quartz, the incoming light remains in the direct part and reflects off the oblique part, but can only be trimmed in one direction. Usually the camera only considers the horizontal resolution, so only the light is made. Horizontal trimming, so the direction should be correct when the filter is attached, can not be reversed. If the vertical light should also be trimmed, what should I do? Very simple, stick two pieces, turn one of them into 90 degrees, so there is This kind of filter, also called “two-piece”, is used for horizontal trimming, one for vertical trimming, and one for IR-Coating to filter infrared.
Generally, the wavelength of visible light is 0.4 to 0.7 micrometers, which is the light that the eye can see. The section from 0.7 to 400 microns is infrared. Infrared is the invisible light that is beyond the reach of human eyes. In addition, any object emits thermal radiation infrared light above zero, and a heat-generating object such as a human body emits a larger amount than objects such as houses, trees, and stones.
The camera’s sensor CCD or CMOS, also commonly referred to as “Sensor, is a semiconductor device that converts optical images into digital signals. But what is more powerful than the eyes is that it can sense some invisible light, such as infrared light. The sensor has an indicator sensitivity.It is also called the illuminance value, which is the ability to respond to weak light. The higher the sensitivity, the stronger the ability to sense light, and the stronger the ability to sense infrared.
Since the sensor can sense infrared light, infrared rays in the light also enter the sensor during the day, which causes the overall image to be reddish. Therefore, ordinary cameras have filters on the surface of the sensor to filter out the infrared rays in the light. If the infrared camera is also attached with such a filter, the infrared light that is actively emitted by the night camera infrared light will also be filtered out, causing the infrared light to fail. In order to avoid this situation, high-end infrared cameras are generally equipped with dual filters, that is, open the infrared filter during the day, filter out the infrared rays in the light, turn off the infrared filter at night, and let the fill infrared light enter the image through the lens.
The above is why the infrared camera can be clearly imaged at night when the human eye can’t see it. Depending on the infrared camera sensor, it can sense infrared rays. In the environment with poor nighttime light, infrared light or infrared heat radiation of the object itself can be used to realize night vision. At the same time, double filters are used to ensure that the images in the daytime are not color cast.
The imaging principle of video surveillance is to convert the information contained in the light into an image signal that can be judged by the human eye. Thus, light is a “necessity” for video surveillance. If the ambient light is low or no light, the video surveillance system will become a display. In this regard, the current industry mainly uses four imaging technologies to achieve night vision monitoring.
When the illumination is low, the camera receives the near-infrared light field of 0.75-1000 m in the natural illumination environment by switching the infrared filter, and enhances the video processing algorithm to let the camera read the image information carried by the received near-infrared light domain. . A kind of photoresistor is placed on the front end of the camera. When the ambient illumination reaches the switching illuminance value set by the camera, the camera automatically switches the infrared filter; and then relies on the algorithm to process the low-illumination video. The most typical low-illumination image processing algorithm It is the automatic gain function, which automatically increases the brightness of the picture as the ambient illumination decreases.
Application of Infrared Thermal Imager in Forest Fire Prevention:
Fire prevention is an important part of forest protection work. Outlook is the most important task.Initially, the fire brigade will stand on the watchtower look around and if found abnormalities report to the forest fire authorities on time,usually watchers are generally based on the smoke situation and color to determine the type of forest fire and Distance, but there are errors and disadvantages of this initial look.
With the development of technology, thermal imaging monitoring gradually appears in the forest fire prevention departments. This kind monitoring is usually placed on top of the watch tower detect and locate the forest fires with high-precision PTZ .This detection method can quickly capture the real-time image of the scene combine with some automatic camera equipment.
Combining the thermal imaging camera with the computer software management platform can automatically monitor forest areas, automatically identify fireworks, and automatically locate fires locations. Use of these instruments, you can set unmanned observation tower in the forest, watchtower can be connected with the command center, so that any data can be monitored timely transmission to the command center, nowadays, many countries in the world, in the forest fire monitoring tower Are using this automatic infrared monitoring system.
Hope-Wish TTVC series dual channel hot spots intelligent alarm thermal camera is designed based on the latest 5th uncooled infrared technology and continuously infrared optical zoom technology. With 336*256 /640*512 uncooled FPA sensor, advanced digital circuit and image processing technology, the camera can provide users a premium image. Built-in intelligent analysis module, hot spot detection algorithm, and can automatically detect the flame, vehicles, personnel and other heat sources over a long distance goal, supplemented by overloading 360°degree PT, which can realize 6000m within the scope of the fire detection and alarm display. One integral aluminum alloy housing sealed with nitrogen and IP66 ingress protection ensures its proper functioning outdoor.
With special FR2000 fire warning platform software, can realize the video display, control, storage, playback, scanning and automatic control, automatic alarm information processing, automatic alarm record, calculate calibration point position, virtual police district management, GIS map information display, meteorological data access, hierarchical management, specialized functions such as dynamic evolution strategy, fighting the fire, very suitable for forest fire prevention, animal husbandry and grassland, coal mine, large-scale granary fire automatic remote monitoring.
With its ability to operate night or day, “see” through foliage and can be used in various weather conditions, infrared thermal imagers can be used in a variety of surveillance and border control situations.
Cross-border and perimeter surveillance: In manhunt or crisis situations, one of the first operational actions is to set up a perimeter. Handheld or vehicle-mounted thermal imagers can make this perimeter more effective in containing and apprehending suspects or detecting and preventing unwanted intruders from invading a restricted area. Highly restricted facilities, such as correctional institutions or industrial plants, can monitor their perimeters night and day with the aid of a thermal imager.
Fugitive Searches: Thermal imagers are excellent at finding people hiding in foliage, regardless of the time of day. By locating a fugitive with a thermal imager, officers can approach and apprehend a suspect without giving away their own location or risking dangerous confrontations. Blind sweeps involving many officers are not needed.
Routine Patrols: The greatest benefit of a thermal imager is the ability to see in darkness. This provides a tremendous advantage during routine patrols and special surveillance missions. Thermal imagers are effective tools in locating discarded contraband or evidence, during undercover stakeout operations or during narcotics interdiction. On the water, thermal imagers are used for nighttime navigation, to locate and track vessels and for search and rescue operations. The passive nature of thermal imaging allows investigators to conduct surveillance undetected and without violating citizens’ rights of privacy.
1. Can thermal imaging cameras really see through walls?
No. The cameras only “see” heat as it radiates off an object. It may see the heat coming from a house, but it can’t see into the house because the camera picks up the house’s exterior thermal profile first. The thermal imager doesn’t even see through glass, because glass has its own thermal profile.
2. Can it see through clothes?
Not really. If a suspect had a gun under his/her coat, the exterior area of the coat would appear “cooler” to the camera and indicate to the police the person may be carrying a gun.
3. How is law enforcement using this technology?
o Officer Safety: locates threats such as hidden suspects, guard dogs and dangerous obstacles;
o Search and Rescue: vision at night; covers large areas quickly and with less manpower;
o Vehicle Pursuits: see vehicles driving without headlights from the air; detects heat of recently-driven vehicles in crowded parking lot or remote area.
Infrared thermal imagers have become more and more familiar in recent years, and more industries are beginning to use and reuse infrared thermal imagers.So, what kinds of infrared thermal imagers are there?Today we will sort it out according to the form of use.
1. Online thermal imager
The online thermal imager is generally fixedly installed during use, and realizes real-time monitoring, alarm and post-data analysis functions through the supporting online software. When selecting this type of thermal imager, the distribution installation scheme is generally determined according to the size of the lens field of view combined with the area of the scene being measured. Currently widely used in industrial automation, petrochemical metallurgy, machine room, warehouse.
2. Handheld thermal imager
Compared with the traditional thermal imager, the general instrument is equipped with a TF card, and the data can be exported through offline software for analysis. The user can move as needed and is easy to carry, suitable for outdoor work. Handheld thermal imaging cameras are equipped with batteries and are widely used in hunting, navigation, search and rescue, military operations, police, fire, petrochemical and other fields.
3. Integrated thermal imager
Due to the increasingly compact design of thermal imagers, more intelligent industries have chosen and integrated technology. The most widely used are: 1). Unmanned aerial vehicle thermal imager: data transmission through the network for analysis, wide range of uses Such as search and rescue, large-scale power station inspection, high-altitude cable fault detection, forest fire prevention, etc., greatly reducing personnel and operating costs; 2), robot integrated thermal imager: when the robot is integrated into the thermal imager, whether it is for fire, smart tour Inspection, night vision armed, etc., have an irreplaceable role; 3), visible light / infrared dual-sensor thermal imaging camera: the use of the cloud platform, the perfect combination of visible light camera and infrared thermal imaging camera, infrared thermal imaging camera temperature imaging / night vision The function is completely combined with the clear recognition/positioning of visible light, and is widely used in industries such as coastal defense, forest fire prevention, and aquaculture.
4. Consumer thermal imager
At present, there are two types of consumer thermal imagers that are most common: 1）. Thermal imaging night vision: Traditional night vision devices require low light assistance to image, while thermal imaging technology can still be clearly imaged without being affected by visible light. Such characteristics just make up for this deficiency, do not actively emit light, good concealment, to protect your night safety; 2）, mobile phone thermal imager: as the name suggests is inserted in the phone, so that the phone has infrared thermal imaging function, generally small size It is easy to carry and widely used in daily homes (floor heating, property construction, self-inspection of inflammation, etc.) and simple replacement of traditional hand-held.