is there an 'out there', out there?
FLIR and you…
James ‘Cap’n Casper’ Presnell: founder
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Lately many paranormal groups have been making wide use of FLIR imaging systems. While quite impressive as a piece of equipment (they start at about 3 or 4 thousand dollars and go up from there), they tend to be a bit misused from what I have seen.
FLIR (Forward Looking InfraRed) systems, sometimes called thermal cameras or thermal scanners are similar in operation to IR thermometers (for more info on IR thermometers, go HERE) in that they measure the amount of emitted IR radiation 
striking the devices sensor. FLIR typically uses a microbolometer, which is similar in operation to a digital camera’s CCD chip. However instead of measuring visible light (wavelengths of about 380 to 750nm), IR camera produce their image in response to emitted heat in the form of infrared radiation (wavelengths from about 750nm up to .03cm). Just like IR thermometers, the heat measured by these devices is emitted heat. Instead of taking one reading, the sensor matrix takes many thousands of readings and presents them as an image so be viewed by the user. The type of image provided by these devices has become familiar to many in recent years. The image is produced by assigning each temperature a color, then using the readings obtained by the sensor to show temperature gradients in the field of view of the lens. Not all images are in color, though. Some thermal cameras display in black and white (think of watching ‘COPS’ and seeing an image from a search helicopter). Special lenses are used in these devices to block out the effects of ambient light on the images.
FLIR devices can be useful if implemented in an appropriate fashion. However, many groups claim that they can see ‘cold spots’. Not true. Because FLIR systems measure emitted heat like IR thermometers, matter that 
is emitting heat is required to obtain a reading. –Remember that by heat, we are talking about anything above absolute zero, or -273 degrees Celsius.– In fact, fire-fighting agencies have been using FLIR systems for a number of years due to their ability to ’see’ through dense smoke inside buildings. Because IR radiation can penetrate dense clouds of particulate matter even in low light conditions, fire rescue personnel may employ the use of a FLIR system to aid in finding trapped people in burning buildings.
I think the primary appeal of FLIR systems is twofold. First, they’re hi-tech. Most people tend to think that hi-tech is good even if it is used improperly. Technology seems to have a knack of adding credence to claims made by someone trying to make a point. Second, thermal cameras allow us to see beyond our senses. We can feel the heat of an object, but seeing that invisible property somehow makes it more real. After all, the human mind runs on images, hence the old adage ’seeing is believing’.
Are FLIR systems useful? Absolutely. Are they sometimes over-used? Absolutely. It all boils down to one invaluable concept: know your equipment. If you are going to spend the money to purchase a FLIR and the time to use it, know why you are using it. Understand how the device works and what it is telling you. Most importantly though, comprehend why that data is useful and what you can learn or infer from it. If we truly want to be scientific and thoughtful in our approaches, we will always endeavor to gain the greatest position of understanding in all that we do.
Thanks for taking the time.
-Cap’n Casper
February 2, 2009 - 12:36 am
I’m a bit confused by your statement that cold spots cannot be “seen”. Your next sentence talk about absolute zero, and depending on the device’ active temperature range it would seem reasonable that a ghost could show even if the temperature is relatively low. It would just show as blue, being in the “colder” part of the spectrum. I would expect that very few objects in nature including spirits if they exist would be colder than absolute zero.
That said it would perhaps be necessary to introduce some heat to the area to make the ghost (blue) stand out from the surroundings.
February 2, 2009 - 10:01 am
That’s a good question. It’s all an issue of emissivity. The operation of such devices depends upon a certain amount of matter that emits a certain amount of heat. Notice that when these devices are used, a person’s breath does not show up. That is beacuse the density of matter in the air is not sufficient to cause the sensor in the device to react. This is the same reason that FLIR systems are used by firefighters. Even though smoke may appear quite dense optically, to a FLIR device, it is mostly transparent because the smoke particles do not have enough density to block the IR radiation coming from, say, a person sitting in the corner of a smoky room.
So, even though there may be temperature gradients in the air, there is not sufficient density to ’see’ them with these devices. Our sense of touch (through the skin and relating to air currents) turns out to be much more fine tuned and sensitive than a FLIR simply due to its method of operation. Remember, the FLIR is not in direct contact with the air molecules and therefore must rely on the emitted IR radiation to function. One possible alternative in the future would be the Schlieren camera. This device actually allows the user to see the air currents and thermal gradients, but for now their size makes them prohibitive to portable use.
Thanks for the question!