Infrared is short for infrared, which is an electromagnetic wave. It enables wireless transmission of data. Since its discovery in 1800, it has been widely used, such as infrared mouse, infrared printer, infrared keyboard and so on. Infrared characteristics: infrared transmission is a point-to-point transmission, wireless, can not be too far away, to align the direction, and there can be no obstacles in the middle that is, can not go through the wall, almost impossible to control the progress of the information transfer; IrDA is already a set of standards, IR receiving / sending components are also standardized products.
Basic introduction Chinese name ：Infrared Foreign name ：Infrared Full name ：Infrared Species ：Electromagnetic waves Time ：1974 Introduction, Introduction to the basic principles of infrared, infrared radiation emission and its laws, the actual object of infrared radiation law, emission rate and its impact on the state of the equipment to monitor the information, between the object of the radiation transfer of the impact of the technical characteristics, features, advantages, disadvantages, interface of the Features,Differences,Infrared Spectrum,Infrared Technology,Infrared Products,Infrared Suites,Emerging Infrared Technologies,From Shutter Glasses for 3D TVs to Sound Systems,Interoperability Challenges of Active Shutter Glasses for 3D TVs,Scholarly Journals,Journal Profiles,Journal Information, Introduction The invention of infrared light in 1974 has brought us a new way of connecting to our devices, and, more importantly, it has brought us new concepts that have made We feel a refreshing sense of wirelessness. Infrared Basic Principles Introduction All objects in nature, as long as its temperature is higher than the absolute temperature (-273 ℃) on the existence of molecules and atoms in the irregular movement of the surface of the infrared radiation is constantly. Infrared is a kind of electromagnetic wave, its wavelength range of 760nm ~ 1mm, not visible to the human eye. Infrared imaging equipment is the detection of this object surface radiation is not visible to the human eye infrared equipment. It reflects the infrared radiation field on the surface of the object, that is, the temperature field.Note: Infrared imaging devices can only reflect the temperature field of the surface of the object.
For power equipment, the basic principle of infrared detection and fault diagnosis is to detect the infrared radiation signal on the surface of the diagnosed equipment, so as to obtain the characteristics of the thermal state of the equipment, and according to this thermal state and the appropriate evidence, to make the equipment with or without faults and fault attributes, the appearance of the location and severity of the diagnosis of the judgment.
In order to better understand the principle of infrared diagnosis of power equipment faults, better detection of equipment faults, the following will be a preliminary discussion of the thermal state of the power equipment and its infrared radiation signals generated by the relationship between the law, the factors affecting the principle of work and DL500E. The emission of infrared radiation and its laws
(a) the black body of the infrared radiation law
The so-called black body, simply put, in any case, for all wavelengths of incident radiation absorption rate is equal to 1 object, that is to say, the full absorption. Obviously, because the actual existence of any object in nature on the different wavelengths of incident radiation have a certain reflection (absorption rate is not equal to 1), so the black body is just an abstraction of an idealized object model. However, the basic law of blackbody thermal radiation is the basis of infrared research and application, which reveals the quantitative relationship between infrared thermal radiation emitted by the blackbody with temperature and wavelength changes.
In the following, I focus on three of these basic laws.
1. Spectral distribution of radiation - Planck's law of radiation
A blackbody with an absolute temperature of T (K), unit surface area in the wavelength λ near the unit wavelength interval to the entire hemispherical space emitted by the radiant power (referred to as the spectral radiance) M λb (T) and the wavelength λ, the temperature T to meet the following relationship:
M λb (T) = C1λ-5 [EXP(C2/λT)-1]-1]
where C1 - the first radiation constant, C1 = 2πhc2 = 3.7415 × 108w-m-2-um4
C2 - the second radiation constant, C2 = hc/k = 1.43879 × 104um-k
Planck's law is the basis of quantitative calculation of infrared radiation. The basis of the introduction of a more abstract, will not go into detail here. 2. The law of change of radiant power with temperature - Stephen Boltzmann law
Stephen Boltzmann law describes the black body unit surface area to the entire hemispherical space emitted by all the wavelengths of the total radiant power Mb (T) (referred to as the full radiance) with the law of change of its temperature. Therefore, the law is Planck's law of radiation to the wavelength integral obtained:
Mb(T)=∫0∞Mλb(T)dλ=σT4
Where σ = π4C1/(15C24)=5.6697×10-8w/(m2-k4), known as the Stefan Boltzmann constant.
The Stefan-Boltzmann law shows that any object with a temperature above zero degrees Kelvin spontaneously emits infrared thermal radiation outward, and that the total radiant power emitted per unit surface area of a blackbody is proportional to the fourth power of the Kelvin temperature. Moreover, whenever there is a small change in temperature, it will cause a large change in the radiant power emitted by the object.
Can we imagine, then, that if we could detect the total radiant power emitted per unit surface area of a blackbody, wouldn't we be able to determine the temperature of the blackbody? Thus, the Stefan-Boltzmann law is the basis for all infrared thermometry. 3. The spatial division of radiation - Lambert's law of cosines
The so-called Lambert's law of cosines, that is, the black body in any direction of the intensity of the radiation and the direction of observation relative to the cosine of the angle between the normal of the surface of the radiation is directly proportional to the cosine of the figure
Iθ = I0COSθ
This law shows that the black body in the direction of the radiation normal to the surface of the radiation of the strongest radiation. Therefore, when actually doing infrared detection. Should be selected as far as possible in the direction of the surface normal to be measured, if the detection in the direction of the angle of θ with the normal, the received infrared radiation signal will be weakened into the normal direction of the maximum value of the COSθ times. The infrared radiation law of the actual object
1. Kirchhoff's law
The ratio of the radiation out of the object M (T) and the absorption principal α, M / α, is independent of the nature of the object, and is equal to the radiation out of the black body at the same temperature, M0 (T). It suggests that the absorption of large objects, the emission of large objects, if the object can not emit a certain wavelength of radiant energy, but also can never absorb this wavelength of radiant energy. 2. Emissivity
Experiments have shown that the radiance of the actual object is not only dependent on the temperature and wavelength, but also related to the material properties of the object and the surface state and other factors. Here, we introduce a radiation coefficient with the material properties and surface state changes, then the basic law of the black body can be applied to the actual object. This radiation coefficient, is often referred to as the emissivity, or called the specific emissivity, which is defined as the actual object and the same temperature blackbody radiation properties of the ratio.
Here, we do not take into account the effect of wavelength, but only study the full emissivity of the object at a certain temperature:
ε(T) = M(T)/M0(T)
Then, Stefan Boltzmann's law applied to real objects can be expressed as follows:
M(T) = ε(T).σT4 Emissivity and its impact on the monitoring of equipment status information Objects For a given incident radiation, there must be absorption, reflection and transmission, and the sum of the absorbance α, reflectance ρ and transmittance τ must be equal to 1:
α+ρ+τ=1
and the reflectance and transmittance components remain constant. Therefore, under conditions of thermal equilibrium, the radiant energy absorbed by an object must be converted into radiant energy emitted from that object. From this, it can be concluded that in thermal equilibrium, the absorption rate of the object must be equal to the emissivity of the object at the same temperature:
α(T) = ε(T)
In fact, from the Kirchhoff's law, we can also infer the above formula:
M(T) / α(T) = M0(T)
ε(T) = α(T)
ε() = M(T)/ α(T) = M(T)/ α(T) = M(T)/ α(T) = M(T)/ ε(T). T) = M(T)/M0(T) Then for an opaque object ε(T) = 1-ρ(T)
According to the above formula, it is not difficult to understand the following factors affecting the emissivity size:
1. The effect of different material properties
Different materials have different properties of radiation absorption or reflection, so their emission properties should be different. Generally, when the temperature is lower than 300K, the emissivity of metal oxides is generally greater than 0.8. 2. Influence of the surface state
The surface of any actual object is not absolutely smooth, and will always show different surface roughness. Therefore, this different surface morphology, will have an impact on the reflectivity, thus affecting the value of the emissivity. The magnitude of this effect also depends on the type of material.
For example, for non-metallic dielectric materials, emissivity is little or no affected by surface roughness. However, for metallic materials, surface roughness will have a large effect on emissivity. For example, for cooked iron, when the surface condition is rough and the temperature is 300K, the emissivity is 0.94; when the surface condition is polished and the temperature is 310K, the emissivity is only 0.28.
In addition, it should be emphasized that, in addition to the surface roughness, some human factors, such as the application of lubricating oils and other deposits (e.g., paints, etc.), can significantly affect the emissivity of the object.
Therefore, it is important to specify the emissivity of the object to be tested. In general, we do not know the emissivity, so we can only use the phase comparison method to identify the fault. For power equipment, its emissivity is generally between 0.85-0.95. 3. 3. Temperature effects
The effect of temperature on different properties of the object is different, it is difficult to make a quantitative analysis,
only in the detection process to pay attention to. The effect of radiation transfer between objects
Above we have discussed the object for a given incident radiation there must be absorption, reflection, and when the thermal equilibrium is reached, the absorbed radiant energy must be converted into radiant energy emitted to the outside. Therefore, when we detect any target in a substation, the detected temperature, there must be other nearby objects.
Therefore, we should pay attention to the direction and time of detection, so that the impact of other objects to minimize.
(E) Atmospheric attenuation of the impact
Atmospheric radiation on the object has absorption, scattering, refraction and other physical processes, the intensity of radiation on the object will have attenuation, we call extinction.
The extinction of the atmosphere is wavelength-dependent and has a clear selectivity. Infrared in the atmosphere there are three wavelength intervals can be basically completely through, we call the atmospheric window, divided into near-infrared (0.76 ~ 1.1um), in the infrared (3 ~ 5um), far-infrared (8 ~ 14).
For power equipment, most of its lower temperature, concentrated in the 300K ~ 600K (27 ℃ ~ 327 ℃) or so, in this temperature range, according to the basic law of infrared can be deduced, the equipment emitted infrared radiation signal, in the far-infrared 8 ~ 14um interval accounted for the largest percentage, and the radiation contrast is also the largest. Therefore, most of the power system infrared detection instruments work within the wavelength of 8 ~ 14um.
Note, however, that even when operating in an atmospheric window, the atmosphere has an extinction effect on the infrared radiation. In particular, water vapor has the greatest effect on IR radiation. Therefore, when detecting, it is better to have the humidity less than 85% or less, and the distance is as close as possible. Technical Characteristics Characteristics Infrared communication technology is suitable for low-cost, cross-platform, point-to-point high-speed data connectivity, especially for embedded systems. Infrared Camera Infrared technology's main application: device interconnection, information gateway. The device interconnection can complete the exchange of files and information in different devices. The information gateway is responsible for connecting information terminals to the Internet. Infrared communication technology has been supported and adopted by many software and hardware vendors around the world, and the current mainstream software and hardware platforms all provide support for it. Infrared technology has been widely applied to mobile computing and mobile communication devices. Infrared transmission is a point-to-point transmission method, wireless, can not be too far away, to align the direction, and there can be no obstacles in the middle, that is, can not go through the wall, almost impossible to control the progress of information transmission; IrDA is already a set of standards, IR receiving / transmitting components are also standardized products. Advantages -It enables wireless data transmission between cell phones and computers; -It allows information exchange between devices that also have infrared interfaces; -At the same time, infrared interfaces can eliminate the need to download or other information exchange costs incurred; -Since the need for docking in order to transmit information, security is strong; Disadvantages -Short communication distance, the communication process can not be moved, the communication is interrupted by the obstacles; -The main purpose of infrared communication technology is to replace the cable to wirelessly transmit information. The main purpose of infrared communication technology is to replace the cable for wireless data transmission, single function, poor scalability. Interface features - used to replace the point-to-point cable - the new communication standards compatible with earlier communication standards - small angle (within 30 degrees cone angle), short distance, point-to-point straight-line data transmission, strong confidentiality - higher transmission rate, the current 4M rate of FIR technology has been widely used, 16M rate of VFIR technology has been released Difference between infrared and Bluetooth Infrared Infrared Infrared Infrared Infrared Infrared Infrared Infrared infrared 1. Distance Infrared: aligned, direct, 0-10 meters, single to single Bluetooth: about 10 meters, to strengthen the signal up to 100 meters, you can go around the corner, can not be aligned, can not be in the same room, the link to the maximum number of up to 7, and at the same time, to distinguish between the hard body. 2. industry infrared: nearly out Bluetooth: has been popularized 3. speed infrared: slow Bluetooth: fast 4. security infrared: no difference Bluetooth: encrypted 5. cost infrared: a few dollars - tens of dollars Bluetooth: tens of dollars - hundreds of dollars 6. speed infrared: the serial port speed, 57,600K/bps ~ 19,200K/bps Bluetooth: 1.1Mb/s ~ 2.1Mb/s or even higher (the speed of the serial port is 576,600K/bps to 19,200K/bps). Mb/s or even higher (Bluetooth 2.0) With the progress of science, infrared has been gradually withdrawn from the market, gradually replaced by the USB connection and Bluetooth, infrared invention of the beginning of the purpose of the short-range wireless connection has been less convenient than the direct use of the USB cable and Bluetooth, so the market with infrared transceiver device machines will be gradually out of people's sight. Infrared Spectroscopy Infrared spectroscopy (IR) is a type of absorption spectroscopy that is distinctly characteristic for the identification and structural analysis of organic compounds. Any two different compounds (except for optical isomerism) generally do not have the same infrared spectrum, so the use of infrared spectroscopy can determine whether two compounds are the same. In addition, some functional groups, although different in the molecule, but also can occur in a certain wavelength range of absorption. Based on the infrared spectrum of a compound it is possible to find out which functional groups are contained in the molecule. In making an infrared spectrogram, fewer samples are required and it is faster, thus it is an effective and commonly used analytical method. Generation: A compound molecule absorbs infrared light at a specific wavelength to produce a jump in the molecular vibrational energy levels, resulting in an infrared absorption spectrum. Different kinds of organic compounds, because they have different functional groups, can absorb different wavelengths of infrared light, in the infrared spectral map shows different characteristic absorption peaks. According to the appearance or otherwise of the characteristic absorption peaks in the infrared spectra, the structural characteristics of organic compounds can be determined. Basic principle: The wavelength of infrared light is in the range of 0.75μm to 300μm, and it is customary to further divide the infrared spectrum into the near infrared (λ=0.75∽3.0μm), the mid-infrared (λ=3.0~30μm), and the far-infrared (λ=30~300μm) three regions. The general infrared absorption spectrum, which mainly refers to the mid-infrared range, has a wave number between 400 and 4000 cm-1. When an organic molecule absorbs the infrared spectrum, the energy of the system increases, producing a jump in the vibrational energy level. The vibration of molecules generally includes the telescopic vibration of the bond and the bending vibration of the bond, the telescopic vibration is the vibration along the axis of the bond, and the bending vibration is the vibration in which the bond angle alternately changes. Of these vibrations only those in which the vibration is a change in dipole moment absorb infrared light. This is due to the fact that the electric field generated by the change in charge distribution caused by the vibration *** vibrates with the electromagnetic field of the infrared radiation and causes absorption. In the vibration energy level changes, often accompanied by a series of rotational energy level changes, measuring the infrared spectrum of organic compounds, the absorption bands seen are continuous peaks and valleys, rather than intermittent linear infrared spectrum. Therefore, infrared spectroscopy is a vibration-rotation spectrum of molecules. Qualitative analysis of infrared spectroscopy: generally use three methods: control with known standards, standard spectrogram checking method and direct spectral analysis method. 1. Known objects should be controlled by the standard and the examined material in the exact same conditions, respectively, infrared spectral mapping for comparison, the spectrum is the same as the same compounds are sure. 2, Reliable method. In checking the standard spectra with the unknowns, it must be noted that: the determination of the instrument used to draw the standard spectra and the differences in resolution and accuracy, may lead to differences in the structure of some of the peaks of the microstructure; unknowns and the standard spectra of the determination of the conditions must be consistent, otherwise the spectra will be a big difference; attention must be paid to the introduction of the effect of the absorption bands of the impurities. For example, KBr pressed tablets may absorb water and introduce water absorption bands, etc. 3. For unknown compounds, the spectra can be analyzed in accordance with the following steps: starting from the characteristic frequency region to find out the main functional groups contained in the compounds; fingerprint region analysis, to further find out the basis for the existence of functional groups; careful analysis of the fingerprint region spectral band position, intensity and shape, to determine the possible structure of the compounds; compared with the standard spectra, together with other means of identification. Further validation. Quantitative analysis of infrared spectroscopy: Select the appropriate quantitative absorption peaks, determine the absorbance of the peaks, and calculate the content of the components to be measured according to the Langbauer-Beer law. Infrared technology The infrared interface is a standard feature of new generation cellular phones, which supports the exchange of data between cellular phones and computers as well as other digital devices. Infrared communication is characterized by low cost, easy connectivity, simplicity and compactness, and is therefore widely used in small mobile devices. Through an infrared interface, various types of mobile devices can freely exchange data. Infrared Laser Infrared is an electromagnetic wave with a wavelength of 750nm to 1mm, which is higher than microwave and lower than visible light, and is a kind of light invisible to human eyes. Because of its shorter wavelength and poorer diffraction capability, infrared is better suited for point-to-point linear data transmission in applications requiring short range wireless communication. The Infrared Data Association (IRDA) limits the wavelength of light used for infrared data communication to 850nm to 900nm. Wireless Internet access on cell phones equipped with an infrared interface is very simple, no wires or PCCARDs are required, just set up the infrared connection protocol and you can access the Internet directly. Infrared interface is currently in the world is widely used in a wireless connection technology, is supported by many hardware and software platforms; through the data of electrical pulses and infrared light pulses between the mutual conversion of data to achieve wireless data sending and receiving. Infrared products 1, infrared intelligent high-speed ball. 2、Infrared camera. 3、Night vision device. 4, Infrared lamp. 5, Infrared light wave oven. 6, Infrared laser. 7, Infrared camera. Scope of infrared set 1, security monitoring field. 2, Automobile night vision system. 3, Medical equipment industry. 4, home electronics industry. 5, communication field. Emerging infrared technology From the shutter glasses of 3D TVs to audio systems New home theater sets rely more and more on infrared. Infrared has been used in home appliances for remote control for over 30 years. Many of us use infrared to control a wide variety of devices every day, including set-top boxes, DVD and Blu-ray players, air conditioners, projectors, laptops and many more. in 2010, more than 700 million infrared receivers were manufactured worldwide, with the majority of these receivers being used in these applications. However, a number of new home theater applications are emerging that broaden the scope of infrared technology in the home. For example, infrared signals are used to synchronize active shutter glasses to 3D TVs. Infrared is also being used as a platform for a new protocol released by Universal Electronics that enables two-way communication between devices and handheld controls. To simplify the installation of a home theater sound system, reduce cluttered wires, and give the room a cleaner look, infrared is even being used to transmit audio signals to the side surround speakers and rear speakers.
There are two types of infrared transmission technologies: direct line-of-sight transmission and scatter transmission. Direct infrared transmission is characterized by the requirement that there be no obstruction in the line of sight between the transmitting and receiving devices. Scattered infrared transmission is non-line-of-sight transmission and is not directional. The infrared light from this type of transmission is much like the light coming from a light bulb. The light reflects back off the walls and ceiling and spills throughout the room. In this article, we'll discuss applying these two principles in some of the emerging infrared sets. The Interoperability Challenge of Active Shutter Glasses for 3D TVs
Active 3D shutter glasses for home theater systems produce a stereoscopic 3D effect by opening and closing the left and right apertures in sync with the image displayed on the TV screen. Infrared light is used to transmit a synchronized signal from the television to the glasses. When the first such glasses were introduced, the industry had to set up a physical layer or dedicated communication protocol standard specifically for these glasses, resulting in a variety of solutions. Some first-generation 3D synchronization systems used the 850 nm wavelength, others used 940 nm. Some first-generation systems used carriers for their transmission protocols, others used unmodulated signals. Different and incompatible data signaling protocols were used in these systems. Some protocols require synchronization over the entire time period, others use phase-locked loops (PLLs). Some systems use one or two transmitter tubes to transmit the synchronization signal, and some will use up to 10 transmitter tubes. Some systems have the transmitter tubes and the remote receiver isolated to avoid crosstalk; others place the transmitter tubes and receiver right next to each other behind the same viewport. These systems are not compatible with each other, so the glasses are customized and expensive.
Because some 3D TVs use the same 940nm infrared wavelength as the IR remote receiver, they interfere with each other. When watching a 3D movie, the sync signal is emitted continuously on and off like a blink of an eye. If the user wants to pause the movie, turn up the volume, or turn on the subtitles, the TV remote control signal has to squeeze through the mass of infrared signals. The TV remote receiver automatically adjusts its gain due to the 3D synchronized IR signals, which reduces the receiver's sensitivity or simply stops it from working, and the reception distance is adversely affected. Users must get closer to the TV to execute commands, or press command buttons repeatedly. This not only affects communication with the set-top box or TV, but also interrupts the remote control signals for DVDs and air conditioners. Unmodulated 3D systems are particularly sensitive to noise pulses from small fluorescent lamps. Some designs use a large number of transmitters because the receiver sensitivity has to be minimized to avoid interference from fluorescent lights and other sources. Unfortunately, 3D systems using such high emitter power can themselves become a primary "noise source", messing up other infrared systems such as remote controls. Academic Journals Journal Description Infrared is a monthly scientific and technical journal approved by the State Press and Publication Administration of the People's Republic of China, supervised by the Chinese Academy of Sciences, and sponsored by the Shanghai Institute of Physics and Technology of the Chinese Academy of Sciences, and was founded in 1980. Infrared magazine mainly reports the latest achievements and development trends in the field of modern infrared optoelectronics and high technology, focusing on the new progress, new trends and new tendencies in infrared optoelectronic detection technology hardware and application. The scope of the report involves infrared materials and devices, infrared remote sensing, infrared imaging, infrared alarm, micro-light and night vision, early warning and guidance, infrared optical communication, infrared medical detection and medical technology, industrial temperature measurement, humidity, width, speed, infrared spectroscopic analysis. In addition to the publication of reviews and research papers, the journal also features news and information on related academic conferences. The purpose of this journal is to transmit and reflect the important information in the field of infrared and optoelectronics science and technology at home and abroad to the readers in a timely manner, and to provide a garden for the majority of scientific researchers to study and exchange, in order to promote the development and improvement of infrared and optoelectronics high and new technology in China, and to serve for the construction of China's national economy. Infrared magazine has been Wipu "Chinese scientific and technical journals database", Wanfang "Chinese core journals (selection) database", China's periodical network of Chinese academic journals (CD-ROM version) of the full-text database and the China Academic Journals Comprehensive Evaluation Database (CNKI), and other important databases included. Infrared" magazine is mainly issued by: engaged in infrared and optoelectronics technology production, research and development, as well as the use of the majority of scientific researchers, scientific research managers at all levels, engineering and technical personnel, as well as teachers and students of colleges and universities. Journal Information Journal Name: Infrared Host: Shanghai Institute of Physics, Chinese Academy of Sciences Publication Period: Monthly Publication Place: Shanghai Language: Chinese Size: Large 16 International Issue No.: 1672-8785 Domestic Issue No.: 31-1304/TN Postal Code: 4-290 Founding Time: 1980 The journal is included in the following databases: CA Chemical Abstracts (USA) ( 2011)