| Added | Wed, 15/02/2017 |
| Источники |
The thermal imager detects heat (infrared) radiation and does not require illumination of the objects to create pictures. They allow us to estimate the temperature difference between the small objects at any time of the day, even in the complicated meteorological situation, partial visibility, and in the far distance.
Infrared radiation is electromagnetic radiation occupy the spectral domain between the red end of visible light (with a wavelength of λ = 0,74 µm and a frequency of 430 THz) and microwave radiation (λ ~ 1-2 mm, frequency 300 GHz).
The whole range of infrared radiation is conventionally divided into three areas:
- near: λ = 0,74—2,5 µm
- medium: λ = 2,5—50 µm
- far: λ = 50-2000 µm
Emit infrared radiation of excited atoms or ions. It is also called "heat radiation", since infrared radiation from hot objects is perceived by human skin as the sensation of heat. The wavelengths emitted by a body depends on the heating temperature: the higher the temperature, the shorter the wavelength and higher radiation intensity. Infrared radiation is emitted by all objects with temperature.
Infrared thermography, thermal imaging or thermal video is a scientific method of obtaining the thermograms (images in infrared light, showing the pattern of distribution of temperature fields). Thermographic camera or thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum (approximately 900-14000 nanometers or 0.9-14 µm) and on the basis of this radiation and create images, allowing to identify overheated or overcooled places.
The principle of operation of modern thermal imagers is based on the ability of certain materials to record radiation in the infrared range.
The imager consists of:
- lens
- delicate matrix
- electronic signal-processing block
By means of an optical instrument composed of lenses manufactured using rare materials transparent to infrared radiation (such as germanium), the thermal radiation of objects is projected on a matrix of sensors sensitive to the infrared radiation. Further, complicated circuits read the information from these sensors, and generate the video signal where the different temperatures of the observed object corresponding to different color image.
Scale matching color dots on the image to the absolute temperature of the observed object can be displayed on top of the frame. You can also specify the temperatures are the hottest and the coldest points in the image.
Depending on the model imagers differ in the step size of the measured temperature. Modern technologies allow to distinguish temperature of objects with an accuracy of 0.05-0.1 degree.
Features a spectral range of 8-14 µm and 3-5. 5 µm, which employs the imagers, such that surface layers of the atmosphere is most transparent for this wavelength, this provides a maximum range of observation of objects emitting in the temperature range from -50 to +500 degrees. Besides, in this range the least interference making atmospheric metaoffline fog, rain, snow, smoke, although the sensitivity of the instruments and reduced.
The sensitive element of the thermal imager is a matrix of CCD-elements chip with a two-dimensional set of light-sensitive photo diodes (charge coupled devices), and modern microelectronics production allows to produce very compact devices with low power consumption and high image quality. To reduce digital noise from the CCD needs to be cooled, that the imaging takes place.
The study of the paranormal often use thermal imagers to identify the Ghost or poltergeist, because it is believed that they tend to locally change the temperature in your presence, as well as when tracking a UFO and determining its shape (or formation, if you track a group of objects), by analogy with otslaivanie aircraft for military purposes, although the expected performance of the UFO is not clearly defined.
Translated by «Yandex.Translator»
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