The wavelength of infrared radiation exceeds that which human vision is able to register and see.
Infrared radiation (IR) is the name given to a type of electromagnetic radiation that is impossible for the human eye to detect. It should be noted that the wavelength of infrared radiation is shorter than that of microwave waves but longer than that associated with visible light .
Any body with a temperature above 0 degrees Kelvin has the ability to emit infrared radiation , experts in the field say. Both the emission and absorption of this type of radiation occur when the rotational-vibrational movements of molecules vary. Using infrared spectroscopy, it is possible to inspect how photons are absorbed or transmitted within the infrared range.
Given the importance of infrared radiation on a universal scale and its wide and diverse field of applications , we will now review its history , highlight its particularities and mention where and how it is used in practice .
Discovery of infrared radiation
Infrared radiation was detected by William Herschel in 1800. This astronomer, who was also trained in the art of music, wanted to determine, using a glass prism and a mercury thermometer , the heat generated by each of the colours . He observed that the heat was more intense on the reddish side, where no light was detected, being an invisible transmission of heat, a radiation that the scientist defined as a caloric ray .
Around 1878 , at the instigation of an inventor, physicist and astronomer named Samuel Pierpont Langley , the bolometer was born. This extremely sensitive instrument, which marked the emergence of IR detector equipment, was used to analyze the infrared radiation of the sun, but was also tested with other elements. With it, new atomic and molecular absorption lines have been found within the infrared zone that can be seen in the electromagnetic spectrum .
It is constructive to know that, from that time onwards, there were inventions, technological advances and discoveries that contributed to learning more about infrared radiation and appreciating it more accurately. The device known as thermopile , the technique called thermography , the development of infrared telescopes and the consolidation of the field of study identified as infrared astronomy are part of the achievements that favored the analysis of infrared radiation .
The thermal image obtained by infrared thermography enables remote (remote) measurement of the temperature of the body being evaluated.
Characteristics
Thermal radiation , as infrared radiation is sometimes called, can extend through a vacuum and be emitted by an object in all kinds of wavelengths .
In order to understand infrared radiation in more detail, it is also essential to understand what emissivity is and what it implies. This property is based on the deflection of thermal emissions from a surface with respect to a black body . That is, a pair of elements, if they differ in terms of emissivity , do not provide an identical infrared image. When the emissivity is not perfect, the object analyzed shows properties of either transparency or reflectivity .
Examples of infrared radiation
The particularities of infrared radiation are revealed by analyzing numerous phenomena and issues, even from everyday life.
Scientific research has shown, for example, that mosquitoes locate their victims (human beings) because they have the ability to detect the infrared radiation emitted by our bodies.
In recent years, a modern heat-generating system based on infrared heating has also been manufactured and marketed. This is a mechanism designed to imitate the process that occurs in the sun so that it can heat the Earth's surface.
In physiotherapy , on the other hand, the so-called infrared light therapy has been used with the aim of increasing the surface temperature of the body area that is being rehabilitated or treated, achieving good results in terms of relieving pain and reducing inflammation in affected areas.
The infrared remote control is characterized by sending orders in the form of an infrared light signal.
Applications
Infrared radiation has applications in the medical field, the commercial sector , the scientific field , the industrial field and the military environment .
Thermal cameras (also known as infrared cameras ) have been around for years and have been used for various purposes. These devices are ideal for observing the state and behaviour of wildlife in their natural habitat at night, for anti-terrorism actions or strategies, surveillance and daily security on public roads, etc.
Infrared thermometers have been used, especially during the pandemic , to ensure measurement or control of body temperature without the need to come into contact with or touch the organism being evaluated.
Infrared sensors are part of the resources used to detect forest fires in many places, and NASA experts have been studying the universe for decades using infrared-sensitive space telescopes . The first infrared telescope launched into Earth's orbit was named IRAS . Its operation has allowed it to collect data of interest on the evolution of galaxies , dark energy , the movement of asteroids , etc.