Introduction
The electromagnetic spectrum is composed of electromagnetic radiations that exhibit different characteristics. Some have a longer wavelength than others. In addition, some have a higher penetration power than others. Gamma Rays, X-rays, Ultra Violet (UV), Visible light, Infra Red (IR) and Radio-waves are common examples. The special characteristics possessed by the electromagnetic make each of them unique. For example, the X-rays are widely used in the medical field due to its high penetration power (Bhusan 65). This paper outlines the various sources, characteristics, components and applications of IR.
Origins and Creation of IR
IR is a form of energy that is easily detected by the skin temperature receptors. It is always referred to as thermal radiation. It is characterized by excessive heat that is either naturally produced or artificially propagated by light emitting diodes, lamps or flames (Chu 452). It should be noted that color, electromagnetic waves and heat levels share a common factor. The color spectrum exhibit temperature differences within the constituent colors present. For example, blue color is characterized by differences in the temperature levels as opposed to the red color. Similarly all other colors and temperature levels are correlated. IR is derived from the fact that the radiation falls below the red band within the visible light spectrum. It is possible to visualize the color red but impossible to perceive IR.
Components and Characteristics of IR
The existence of IR is usually between the visible light and the UV bands. Consequently, the wavelength of IR is longer than that of the visible light but shorter than that of UV.IR cannot be perceived by the human eye. However, it can be felt by the human body. Animals and humans generate IR by virtue of generating heat from their bodies. Radiations deemed to have a wavelength of 9.4um are categorized as IR. However the penetration power of IR is low compared to visible light. It is for this reason that the radiation cannot pass through ordinary window glass and plastic. On the contrary, IR passes through opaque objects such as germanium, silicon and polyethylene. The latter is used in the manufacture of Fresnel lenses, used to in IR sensors.
The emission of IR is characterized by the existence of smaller regions within the IR band. The International Commission on Illumination (CIE) considers the IR band to be composed of five bands namely; Near IR (NIR), Short wavelength IR (SWIR), Mid-wavelength IR (MWIR), Long wavelength IR (LWIR) and Far IR. The respective wavelength ranges for these bands are 0.75-1.4 um, 1.4-3 µm, 3-8 µm, 8–15 µm and 15 – 1,000 µm. NIR and SWIR exhibit increased reflection properties and are therefore referred to as reflected IR. MWIR and LWIR are however characterized by increased absorption (Pereira 107). Consequently, they are referred to as thermal IR.
How IR Works
IR performs different tasks depending on the characteristics of the regions mentioned above. Signal transmission over long distances and remote control technology depend on IR pulses. A clear understanding of how IR works can be conceptualized by examining the heat energy produced by heated objects (Siegel 104). In some cases the heat energy may be in form of visible. Otherwise, the heat energy may be produced as invisible light. This phenomenon is however possible in the IR spectrum.
This form of energy has found its application in industries and medical institutions. The heat energy is usually sensed by electronic equipment. Night-vision goggles are sensitive to heat energy within the IR spectrum. The goggles allow for ‘night’ vision. IR technology is applied in the military. Fire fighters make use of the technology in fire rescue missions (Siegel 108).
In addition, astronomers can be able to analyze the light from distance space objects. It is vitally important have an intricate knowledge of IR technology. The choice of building and insulating heating devices such as convection ovens is improved. Higher temperatures are experienced in conditions of short wavelengths. The visible red and invisible red are separated by wavelength variations. Red parts are usually the warmest. Subsequently yellow and other parts of the spectrum show a decreasing trend of thermal energy. Medically, diseased tissues exhibit a red or shaded appearance that differs from the healthy tissues. Thermography makes it possible to measure insignificant temperature differences. Subsequently, the energy is converted to the color spectrum (Pereira 117).
Uses of IR
IR technology has become one of the most important discoveries of modern time. The common uses of the technology are evident in meteorology, medicine, astronomy, communication and security industries. The chemical contents contained in a bioreactor can be detected using near infrared (NIR) technology (Morris 7). Proper control of nutrients can be timed and optimized. The chemical properties of a substance in regards to NIR reflectance are usually determined using the technology. Medical diagnostics employ the technology in blood testing (Stuart 162). The discovery and production of more effective medicine have been made possible courtesy of NIR technology.
Tablets and capsules can effectively be formulated. Spectrometers, spectrophotometers and spectrographs are important instruments that work on the principle of NIR technology (Stuart 174). The fact that these instruments are capable of detecting cell cultures makes them important in anatomy and microbial studies. They are sometimes referred to as NIR analyzers.
The use of NIR technology in the world of astronomy is common. Through it, the age, spectral characteristics, mass and chemical composition of a star can be ascertained (Casoli 165). This application affirms that NIR technology is useful in the examination of distant objects. The atmospheres of cool and warm stars can be examined by NIR rays. The industrial sector also enjoys a great deal of NIR technology. NIR instruments play a role in the recycling of carpet fiber to newer carpets. The sorting of nylon, polyester, cotton and wool is an important process in the textile industry where NIR technology is of use (Morris 9).
The polymerization process is made easier by the technology. The electronics industry also relies heavily on the technology. Remote controls for TVs, video recorders and mobile phones work on this technology. Camcorders and mobile phone cameras depend on the ability of CCD chips to pick IR waves. Sensitive IR detectors ensure that ‘night sight’ is achieved (Chu 500). Passive Infra-Red (PIR) detectors are used in the field of security. Burglar alarm systems are fitted in most houses. The devices detect the IR produced by people and animals. In meteorology; weather forecasters can make weather predictions by use of satellites. The satellites work on the IR technology.
IR Cameras
IR cameras depend on IR radiation as opposed to normal cameras that depend on visible light. Whereas normal cameras work within a wavelength range of 450-750 nanometers, a wavelength of 14000 nanometers is favorable for IR cameras.IR cameras can also be referred to as thermographic cameras. They are classified on basis of whether the detectors are cooled or un-cooled. The cameras do not require ambient light conditions (Sadowski 37).
Hence total darkness does not impair their operation. Rescue operations in smoke filled buildings are usually successful courtesy of these cameras. The cameras are characterized by a single color channel. This is observed because the sensors are unable to differentiate the wavelengths within the IR range (Bhusan 70) Color cameras therefore have a complex structure. The display of images is sometimes in pseudo-color.
In this context, the variations in color rather than the intensity are employed in the display of the signal. Density slicing makes it possible to differentiate images from IR cameras. Temperature measurement is characterized white, yellow and red, and blue colors for the warmest, intermediate and coolest parts respectively. Unlike normal cameras, IR cameras have a lower resolution and are more expensive (Sadowski 39).
Thermal imaging photography is employed by firefighters in the localization of fire hotspots (Siegel 110). Power line technicians also find the imaging important in the location of overheating joints. Consequently, potential hazards are averted. Air conditioning is also improved through enhanced monitoring of heat leaks within buildings. Astronomical telescopes make use of cooled IR cameras.
Conclusion
IR is one of the most important in the electromagnetic spectrum. The radiation is usually referred to as thermal radiation. Animals and human beings are potential sources of the radiation. In addition lamps, diodes and flames emit the radiation. It is divided into five regions; Near IR (NIR), Short wavelength IR (SWIR), Mid-wavelength IR (MWIR), Long wavelength IR (LWIR) and Far IR. Color and temperature levels have usually related a fact that brings about variations within the IR regions. The applications of the IR radiation are diverse. They include medical analysis, astronomical studies, spectroscopy, communication and security tracking. The fact that most industries are adopting IR technologies is encouraging. Technological advancements are likely to see the replacement of MRI scanners by NIR devices.
Works Cited
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