Thermal Imaging Cameras:

 

There is much talk about thermal imaging in the paranormal but the only thing I hear is that it is the piece of equipment to have. A couple of sites have some information on the subject but not much. I happened to run across some really good information while scanning the different websites and found a great deal of information on the SPI (The Society for Paranormal Investigation) website.

The first thing you need to have is a definition of thermal imaging or thermography. Thermal Imaging is the conversion of radiated or reflected heat into real-time video or images. A thermal image is an analogue pictorial representation or visualization of temperature differences. All objects above absolute zero (-273 K) emit radiation, some of which is infra-red. Depending on temperature and emissivity, most objects in the world can be thermally imaged.

Now let's take a look at the infrared spectrum, the area that the camera is sensitive. Infrared covers four regions of the spectrum, Near infrared, 0.7 -1 micron, this is nearest to the visible wavelength, Short wave, 1.0 - 2.5 microns, both of these wavelengths regions rely on reflected solar radiation and can only be used in daylight or illuminated conditions. Medium or short wave infrared, 3 to 5 microns, is radiation emitted from objects and can be used in total darkness or daylight. Far infrared, 8 -14 microns, is most commonly used in industry since the detectors are efficient at environmental temperatures and can also be used for high temperature operations with appropriate filtering.

Most thermal imaging optic materials are opaque to medium and long wave infrared including glass and water. Optical materials such as germanium and some other exotic materials such as zinc sulphide, zinc selenide, magnesium fluoride and sapphire are used since they are mostly transparent to the thermal wavelength. These materials are very expensive. Some low grade commercial thermal imagers utilize composite materials to lower the costs but there is no compromise where quality is required. Most military specification thermal imager's use coated germanium and optical magnification rather than digital magnification. The ICI camera utilizes diamond coated optics.

Over the past few years there has been an incredible advancement in thermal imaging technology. Miniature electronics has allowed for cameras to become much smaller and far more efficient however the optics and detectors are still very expensive. Industrial applications can be broken down into two basic categories; Ground and Aerial. Although it is not quite this simple, most ground applications can be accommodated using good quality hand-held equipment. Aerial surveys however require high thermal and spatial resolution to provide quality data at long range. The most common types of thermal imaging equipment used in industry are: Pyro-Electric Vidicon, (PEV), Focal Plane Array (FPA) and the SPRITE (Signal Processing In The Element). The PEV is the lower end of the price scale and image quality but is perfectly acceptable for Electrical Condition Monitoring and close proximity surveys. The FPA is usually of mid range and is used for general survey applications. The SRITE detector is generally used in top grade military equipment.

Aerial or Ground infrared, also known as Thermal Imaging or Thermography, is best suited to give qualitative rather than quantitative data. Infrared non-contact quantitative systems need accurate information of surface emissivities if radiant energy is to accurately relate to surface temperature. Thermal images recorded in 8 -14 micron wavelengths (Long Wave) have no visible content and no natural color. Because of the long wavelength, thermal or infrared images cannot compare in spatial resolution to visible photographs that are recorded in 0.4 -0.8 micron band. Thermal resolution and spatial resolution are inter-dependant to produce good quality thermal images, therefore if a house roof is close to or the same temperature as the nearby road, for example, the image will appear dull grey with little detail. Temperature contrast will produce picture or image contrast and high detail. Thermal imagers detect and record Infra-red radiation emitted from the surface of any subject being viewed. The imager does not have the ability to see below the surface. However, the radiation from the surface is often influenced by sub-surface detail, which affects the thermal characteristics of adjoining material(s).

When looking at a large area, the emissivity of various surfaces must be considered. Most materials found on the surface of buildings will have a relatively high emissivity but there will still be noticeable differences in the perceived image due to a change in surface material. This can be overcome by a detailed knowledge of the building under investigation. Some metals and glass can reflect infra-red radiation and apparent 'hot spots' can be a reflection from a hot object nearby. Infra-red aerial surveys provide a 'global' visualization of heat radiation from building surfaces. It is useful data for determining areas of concern or for determining work priority. We can also provide detailed ground level thermal imaging surveys in support of aerial data. Infra-red surveys of heated buildings are always conducted during the evenings of the Winter/Autumn months of the year. Aerial thermal Imaging for surveying buildings for heat loss and moisture operate in 8-14 micron wavelength and detect heat only, visible light is not detected at all. Heat energy from daytime sunshine can be absorbed in brickwork and therefore a survey is conducted well after sunset to ensure that all effects of solar energy have dissipated. Infra-red - just like visible light - absorbs, reflects and re-radiates from materials in amounts depending upon their color and structure. Brown building bricks for example absorb and retain heat energy more readily than lighter colored building materials; this must be considered when analyzing data since they may effectively appear at different temperatures simply due to their emissivity. Water bodies such as rivers or lakes retain heat and are slow to change with ambient temperature changes, whereas ground surface temperatures can change rapidly. This is why water often appears warmer than its surroundings. A thermal Imager detects and displays surface temperatures only. The surface temperature under normal conditions is the result of heat energy conduction through the walls from a heated internal room. Moisture is an excellent conductor of heat and when insulation is damp it can become a conductor rather than an insulator. When analyzing thermal data, monochrome images are normally preferred because of the wide range of grey tones of temperature that can be differentiated by computer. There are of course no natural colors in the long wave infra-red wavelength so we apply a palette of colors to the grey tones. Color images are much easier for the naked eye to interpret so both color and monochrome are supplied. To assist in analyzing your aerial data a temperature palette is provided for assessing temperature differences. The preceeding article on Thermal Cameras can be located on the SPI website (SPI) at www.spi.com.

Now the question's are, can I afford one of these little joules? How much training should I get in the field of thermography? And how can this help me in my quest to gather information in my paranormal investigation? My suggestion would be to take a class on basic thermography or take a course in remote sensing at your local university. If you are willing to spend $5000.00 to $40,000.00 on a thermal camera, the small fee of a course would benefit you. The course will not only help you to understand the concepts of thermography but can also guide you in a purchase. Remember, the local Fire Station is not the place to look for a thermal camera. They may have one they don't use but you will need to go to a city auction to acquire it if they are selling them. The last one I looked at from a city auction was a dome type thermal that sat on top of a squad car at the police department. It was too big and bulky to be of any use, unless you wanted to mount it on your car and drive around the cemetery at night looking for ghost. I would suggest not spending the money unless you have a good understanding of the concepts.

We purchased the ICI ToughCan EL. The new ToughCam EL portable thermal imager has outstanding image quality and radiometric temperature measurement performance in a rugged and easy to use infrared camera. The Toughcam EL camera is equipped with single point temperature measurement. The camera has a resolution of 160 x 120 and a temperature measurement range of -20° to 250° C (-4° to 482° F). Its lithium ion battery supplies 3 hours of continuous operations per charge. ICIReporter software provides quick accessibility to a full range of tools for analyzing Toughcam images.

The perfect add on to this camera is the PV-800 body worn DVR. Here are some of the PV-800's features, Super high resolution, able to record 720 x 480 super high resolution quality picture into SD memory card slot for from 1 to 16 GB Memory, 30 GB hard drive built in, output power supply, true time and date stamping, high capacity battery, motion activated option, 1000 mA/3.6V high capacity mini standard cell-phone type rechargeable "quick swap" battery, small pocket size: 5 inches long x 3 inches wide x 3/4th of an inch deep, one touch record button. Easy playback using IR remote control.

Hopefully I have supplied you with enough information to help you if you do decide to purchase a thermal imaging camera. I would suggest looking on the ICI website to follow up on a purchase. Don't be caught up in the Flir name just because you see it on TV's Ghost Hunters. www.infraredcamerasinc.com, the folks at ICI are great and are more than willing to help. I can't say enough good things about them, they are the best.

Lance Brooks (TSS Co-founder, Tech Manager and Lead Investigator)