Blog Date: 10/21/2013
Author: Ray Coulombe
In the last several years, thermal imaging cameras have become mainstream, finding their way into several front-line manufacturers’ IP camera offerings.
Thermal imaging is based on heat sensing from a surveillance target, where feature discrimination is based on temperature differences and does not rely on external source lighting. This is known as passive IR, in contrast to those situations which employ IR illuminators to enhance the low light performance of standard monochrome or day/night cameras. The technology has its roots in military applications, where IR seekers and imagers have been used in weapons and reconnaissance systems. Most passive IR systems, including PIR intrusion sensors, work in the long wavelength IR (LWIR) range of 8 - 14 μm, far out of the visible range. A significant advantage of passive IR in this range is that elements in the atmosphere, such as fog or smoke, which obscure or block visibility in the visible and the near IR bands, are almost transparent to LWIR.
The increasing commercialization of thermal imagers has been made possible by developments in a device with an odd-sounding name. The microbolometer, a detector based on micro-electromechanical (MEMS) technology, detects changes in temperature caused by the incoming 8 – 12 μm heat radiation which affects its electrical resistance. Importantly, the device requires no external cooling to create useful sensitivity. In January 2011, I wrote that the increasing use of silicon in these imagers, coupled with advancements in packaging, would lead to less expensive, more compact optics and cameras. We are now seeing this in the market in a now familiar pattern - military-based technology and consumer driven costs. New families of lower cost camera cores are opening the door to new products and affordable applications.
At the Association for Unmanned Vehicle Systems International Conference in August, FLIR Corporation revealed a prototype camera small enough to fit into a smartphone. FLIR has been a major supplier of infrared equipment to the military and security market for years, so it’s interesting that they’ve revealed a smartphone application. But, as CEO Andy Teich explained, FLIR sees a parallel between IR and GPS, following a cost and adoption curve beginning with military, proceeding through dual military-commercial use, followed by broad commercial use, and, eventually commoditization. He maintains that we have now entered the broad commercial use phase and expects continuing adoption of thermal imaging. 'Our mantra is ‘Infrared Everywhere’', Teich said, 'and we really view infrared becoming the sixth sense for human activity to ‘see’ what’s out there in ways the human eye can’t.' This adoption will continue in Unmanned Aerial Vehicle (UAV), battlefield, and other defense and security applications, while broader commercial applications become more apparent. As Teich admits, the technology is ‘not yet cheap enough to become ubiquitous, but it will get there.’
Speaking of getting there, passive IR technology is becoming available for the masses, as we are beginning to see in various blog pages and early-stage company offerings. MikroSens (www.mikrosens.com.tr) has developed a QCIF (160x120) infrared sensor with NETD <280 mK and USB output. Mμ Optics (www.muoptics.com) started in January with plans to sell a similar imaging device. RH Workshop (www.rhworkshop.com) has developed an open source hardware device known as IR Blue, an accessory for Android and Apple IOS devices. It uses a non-contact InfraRed sensor array by Melexis to superimpose a thermal signature over what’s being viewed on the phone’s camera. At 64 pixels and ~250 mK NETD, this is a far different animal than what I’ve described earlier. However, these devices open up a potential new set of sensing possibilities, raise awareness, and, perhaps most importantly, put low power thermal imaging into the hands of gadgeteers and tinkerers around the world to conceive new interesting applications. At some point, we should expect to reach a tipping point where devices exhibit the right combination of performance and cost to be widely deployed.
Current main stream applications include thermal views for control and PSIM systems, intrusion sensing, cargo security, passenger screening, counter-terrorism operations, rescue applications as well as enhanced video analytics and recording. With thermal technology continuing to evolve, we’ll no doubt see more.
Link to Complete Article as it appeared in Security Technology Executive Magazine