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American COP Jan/Feb 2011 Digital Edition - Page 48
Thermograms & NaNo-secoNds? Why Thermal The StalkIR is only a little larger than the SkeetIR but has twice the resolution. It too can be mounted on a flip-away base or used as a handheld observation devise. Robbie Barrkman Imaging is HOT! magine seeing when there’s apparently nothing to see. That’s quite a trick, right? Not necessarily — not when you have the right equipment. Thermal Imaging (TI) is a technology helping you see the unseeable. Everything has a certain temperature and emits what is known as Infrared Radiation (IR). Hot objects emit more infrared radiation than cold objects, and TI has the ability to detect these variations in infrared radiation between surfaces, which it then displays on a miniature screen. American COP reviewed two TI products from OASYS Technology, the SkeetIR and the StalkIR, both of which are only slightly bigger than the footprint of a credit card. They serve as both a weapon sight and surveillance tool. So how does something literally fitting into the palm of your hand take infrared radiation and turn it into something your eyes can see? It all starts at the front lens. The front lens, made of a material called Germanium, first focuses on the infrared radiation emitted by all the objects in the scene being viewed. Infrared detectors then scan this focused energy and create a very detailed temperature-based mapping called a thermogram. The thermogram represents thousands of temperature readings taken at one time from various points in the “scene” — in about onethirtieth of a second. Next, the thermogram is converted into electronic impulses, which are then processed and sent to the display. Differing grey-scale values are used to represent differing levels of thermal intensity (temperature) found in the scene. The resulting real-time image you see is similar to a black and white negative. I One small powerhouse — The OASYS SkeetIR has a footprint only slightly larger than a credit card and packs all the power of larger units. Running Hot & Cold My first experience with OASYS Technology’s SkeetIR and StalkIR thermal image units was not long ago on a hot desert night. I was inside a building and watched someone turn on a hallway light. How much time would you say that takes, a fraction of a second? Continued on page 64 48 WWW.AMERICANCOPMAGAZINE.COM • JANUARY/FEBRUARY 2011