Thermal Imaging Camera
Detection of Radiation in the Infrared Range of the Electromagnetic Spectrum



 
Ghost Hunting Equipment: Thermal Imaging Camera
Detection of Radiation in the Infrared Range of the Electromagnetic Spectrum


Thermal Imaging Cameras are used to help provide evidence of the paranormal field by detecting energy (heat) which the human eye may not be able to see. Another theory of spirits is that since they may contain energy that they will in return have heat. Cold spots is another theory that suggests that these spirits absorb energy around them to manifest themselves which in turn they create a cold spot.




Infrared thermography, thermal imaging, and thermal video, are examples of infrared imaging science. Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 µm) and produce images of that radiation, called thermograms.

Since infrared radiation is emitted by all objects near room temperature, according to the black body radiation law, thermography makes it possible to see one's environment with or without visible illumination.

The amount of radiation emitted by an object increases with temperature; therefore, thermography allows one to see variations in temperature.

When viewed through a thermal imaging camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded  animals become easily visible against the environment, day or night. As a result, thermography is particularly useful to the military and to security services.

Thermography has a long history, although its use has increased dramatically with the commercial and industrial applications of the past fifty years. Government and airport personnel used thermography to detect suspected swine flu cases during the 2009 pandemic. Firefighters use thermography to see through smoke, to find persons, and to localize the base of a fire.


FLIR ThermoVision Scout Thermal Imaging Scope

This is a FLIR ThermoVision Scout, a high end thermal imaging camera.

These cameras are used in many different Military and Law Enforcement operations and also have been used in many other fields such as in the ventilation industry to detect airflow and leaks. These scopes have even been used in Ghost Hunting.


Maintenance technicians use thermography to locate overheating joints and sections of power lines, which are a tell-tale sign of impending failure.

Building construction technicians can see thermal signatures that indicate heat leaks in faulty thermal insulation and can use the results to improve the efficiency of heating and air-conditioning units.

Some physiological changes in human beings and other warm-blooded animals can also be monitored with thermal imaging during clinical diagnostics.

The appearance and operation of a modern thermographic camera is often similar to a camcorder. Often the live thermogram reveals temperature variations so clearly that a photograph is not necessary for analysis. A recording module is therefore not always built-in.


Thermography

Thermal images, or thermograms, are actually visual displays of the amount of infrared energy emitted, transmitted, and reflected by an object. Because there are multiple sources of the infrared energy, it is difficult to get an accurate temperature of an object using this method.

A thermal imaging camera is capable of performing algorithms to interpret that data and build an image. Although the image shows the viewer an approximation of the temperature at which the object is operating, the camera is actually using multiple sources of data based on the areas surrounding the object to determine that value rather than detecting the actual temperature.

This phenomenon may become clearer upon consideration of the formula Incident Energy = Emitted Energy + Transmitted Energy + Reflected Energy where Incident Energy is the energy profile when viewed through a thermal imaging camera. Emitted Energy is generally what is intended to be measured.

Transmitted Energy is the energy that passes through the subject from a remote thermal source. Reflected Energy is the amount of energy that reflects off the surface of the object from a remote thermal source. If the object is radiating at a higher temperature than its surroundings, then power transfer will be taking place and power will be radiating from warm to cold following the principle stated in the Second Law of Thermodynamics.

So if there is a cool area in the thermogram, that object will be absorbing the radiation emitted by the warm object. The ability of both objects to emit or absorb this radiation is called emissivity.

Under outdoor environments, convective cooling from wind may also need to be considered when trying to get an accurate temperature reading. The thermal imaging camera would next employ a series of mathematical algorithms.

Since the camera is only able to see the electromagnetic radiation that is impossible to detect with the human eye, it will build a picture in the viewer and record a visible picture, usually in a JPG format. In order to perform the role of noncontact temperature recorder, the camera will change the temperature of the object being viewed with its emissivity setting.

Other algorithms can be used to affect the measurement, including the transmission ability of the transmitting medium (usually air) and the temperature of that transmitting medium. All these settings will affect the ultimate output for the temperature of the object being viewed.



FLIR Thermal Imaging Camera

A full body apparition is captured with the FLIR Thermal Imaging Camera.

Garden State Ghost Hunter Investigators Boni Bates and Rob Reid along with cameraman Dave Goldstein witness this Thermal anomaly in this hallway of an Undisclosed Location.


The CCD and CMOS sensors used for visible light cameras are sensitive only to the nonthermal part of the infrared spectrum called near-infrared (NIR).

Thermal imaging cameras use specialized focal plane arrays (FPAs) that respond to longer wavelengths (mid- and long-wavelength infrared).

The most common types are InSb, InGaAs, HgCdTe and QWIP FPA. The newest technologies use low-cost, uncooled microbolometers as FPA sensors. Their resolution is considerably lower than that of optical cameras, mostly 160x120 or 320x240 pixels, up to 640x512 for the most expensive models.

Thermal imaging cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often export-restricted due to the military uses for this technology. Older bolometers or more sensitive models such as InSb require cryogenic cooling, usually by a miniature Stirling cycle refrigerator or liquid nitrogen.



Advantages of Thermography
  • It shows a visual picture so temperatures over a large area can be compared
  • It is capable of catching moving targets in real time
  • It can be used to measure or observe in areas inaccessible or hazardous for other methods
  • It is a non-destructive test method
  • It can be used to detect objects in dark areas

Disadvantages of Thermography
  • Due to the low volume of thermal cameras, quality cameras often have a high price range (often US$6,000 or more)
  • Images can be difficult to interpret accurately when based upon certain objects, specifically objects with erratic temperatures, although this problem is reduced in active thermal imaging
  • Accurate temperature measurements are hindered by differing emissivities and reflections from other surfaces
  • Most cameras have ±2% accuracy or worse and are not as accurate as contact methods
  • Only able to directly detect surface temperatures