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THINGS
Engineers Should Know About Thermal Imaging
A guide for integrating thermal sensor technology into your next project
CONTENT
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Introduction 1.
Today’s thermal technology and a new world of applications
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What is thermal imaging?
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How do thermal cameras work?
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How do I pick the right thermal imager for my integrated product?
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Do I need radiometry or just imaging capability?
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What should I look for in an IR supplier?
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What is the total cost of ownership?
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Do thermal cameras require export licenses?
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INTRODUCTION Adding thermal imaging sensors to your next project can give your customers the ability to see the unseen, and expand their senses into the unknown. If you’re considering adding thermal sensors to your next design, there are a few things you should consider to make sure you’re getting the capability you need.
Thermal imagers create images from differences in heat energy, so anything that creates heat can be seen with thermal.
Circuit board as seen by a visible camera
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Circuit board as seen by a Thermal Camera
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TODAY’S THERMAL TECHNOLOGY AND A NEW WORLD OF APPLICATIONS. Might thermal imaging have a place in your next product design? It probably does, but first you have to understand what thermal really does – aside from ghost hunting and not finding Bigfoot on TV. Thermal imagers detect and display differences in the relative intensities of the infrared energy being emitted or reflected from an object. This emitted infrared energy is around us all the time, and has nothing to do with the amount of visible light that is available. This is important to remember, because thermal imaging is far more than just another kind of night vision – it sees heat, not light, and it does it 24 hours a day. In the end, thermal imagers create images from differences in heat energy, so anything that creates heat can be seen with thermal. People, animals, electro-mechanical systems, and industrial processes all have individual heat signatures that can be seen with a thermal camera.
Thermal imaging is far more than just another kind of night vision – it sees heat, not light, and it does it 24 hours a day.
The military and law enforcement applications of infrared imaging have been known and proven for decades. But recent technological advances have made them smaller, lighter, and more affordable for commercial and consumer applications as well so it’s a good idea to be familiar with all of the different capabilities thermal brings. Thermal cameras see through smoke, so they’re a proven tool for firefighting and search and rescue operations. This opens up a whole new range of applications, since thermal imagers are perfectly suited to detecting the differences in heat that can give away the presence of people or animals, seeing through smoke, dust or in complete darkness, and detecting electro-mechanical parts that are wearing out or nearing a failure point. For applications where privacy is an important concern, like residential video security, thermal cameras provide the added benefits of not creating an image in which it’s possible to identify facial features, and they don’t see through windows. But thermal technology can also be used as a sensor, not just a camera. It is an orthogonal technology that compliments visible imagers to reduce false alarms in security applications and potentially LIDAR, radar, and visible cameras in new and exciting fields such as ADAS (advanced driver assistance systems) and self-driving cars.
See in Total Darkness See Through Obscurants Measure Temperatures Enhanced Long Range Imaging Accurately Detect People & Animals
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Automotive Diagnostics
Intelligent Transportation
Outdoor Recreation
Industrial Sensing
First Responders
Professional Security
Home Automation
BENEFITS OF THERMAL SENSORS
Smartphones
Since thermal imagers and sensors don’t need any light to create images or detect the presence of people or animals they can be used for everything from home security cameras and person-inroom detectors for home automation, to gesture recognition in game consoles and driver’s vision enhancement in automotive applications
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WHAT IS THERMAL IMAGING? Thermal imagers detect and display differences in infrared energy, using those differences to make greyscale or color images. Infrared energy is part of the electromagnetic spectrum with wavelengths long enough that they can’t be seen by the human eye. Because of this, thermal imagers can create images without using visible light, enabling them to detect very small temperature differences in total darkness, as well as through smoke, dust, and light fog. Everything on earth gives off infrared energy – even ice. In fact, anything above Absolute Zero – the temperature at which all molecular activity stops – theoretically emits some level of infrared and can be detected by a thermal camera given the right conditions. The warmer an object becomes, the more heat energy it emits.
Thermal imagers can create images without using visible light, enabling them to detect very small temperature differences in total darkness, as well as through smoke, dust, and light fog.
The type of electromagnetic energy we’re all the most familiar with is visible light. Visible light is actually a very narrow waveband, only encompassing the range of 0.39 to 0.75 micrometers (µm). The infrared waveband is much larger by comparison, beginning near 1.0 µm and ending at 1,000 µm. As far as our discussion of imaging with infrared energy is concerned, however, we’re talking about these specific subsets of energy: • Shortwave infrared (SWIR) waveband from approximately 0.9-1.7 µm • Midwave infrared (MWIR) waveband from 3-5 µm • Longwave infrared (LWIR) waveband from 8-14 µm
ELECTROMAGNETIC SPECTRUM Visible Spectrum Increasing Frequency Gamma Rays
X - Rays UV
Near Infrared Shortwave (NIR) (SWIR)
Infrared (IR)
Microwave FM AM
Midwave (MWIR)
Long Radio Waves
Radio Waves
Longwave Infrared (LWIR)
Increasing Wavelength www.flir.com
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HOW DO THERMAL CAMERAS WORK? Thermal cameras capture the infrared energy that is all around us and use that energy to create images or data points through digital or analog video outputs. A thermal camera is typically only sensitive to one of the wavebands we discussed earlier: either MWIR from 3-5 µm or LWIR from 8-14 µm. Although there are exceptions, for the most part MWIR cameras require the infrared detector to be chilled to roughly 77 Kelvin with an on-board cryogenic cooler in order to create an image. These coolers add size, weight, complexity, cost, and require periodic maintenance. Uncooled LWIR imagers – like Lepton and Boson – can create images at ambient temperatures, so they’re smaller, lighter, less complex, and less costly than their cooled counterparts. The camera itself is made up of a lens, a thermal sensor, processing electronics, and a mechanical housing. The lens focuses infrared energy onto the sensor (also called a detector). LWIR detectors from FLIR are made of Vanadium Oxide (VOx), which is the most sensitive material for detecting longwave radiation and doesn’t produce the image artifacts typically produced by detector materials like Amorphous Silicone. These detectors are actually an array of detector elements, and can come in a variety of pixel configurations, the most common of which are 320x256 and 640x512. This is the resolution of the detector.
Thermal detectors have to be able to sense energy that has much larger wavelengths compared to visible light, requiring each sensor element to be significantly larger.
While these resolutions seem quite low in comparison to visible light imagers, there’s a reason for that. The individual detector elements themselves are much larger in thermal cameras than they are in visible cameras – visible cameras have pixels that are only 1-2 µm, while thermal camera detector elements are 12-17 µm each! This is because thermal detectors have to be able to sense energy that has much larger wavelengths compared to visible light, requiring each sensor element to be significantly larger. As a result, a thermal camera usually has much lower resolution (fewer pixels) when compared to visible sensors of the same mechanical size. After the thermal energy hits the detector, the readout electronics convert it into a signal that can either be passed out of the camera, or – with cutting edge cameras like the FLIR Boson – go directly into systemon-a-chip circuitry. This SOC gives the camera built-in capabilities like image processing, analytics, and other advanced capabilities that used to require back-end electronics developed by the integrator. Lenses used in thermal cameras from FLIR are made of Germanium or Chalcogenide, because those materials are highly transparent to longwave radiation. Thermal cameras can’t use the same lens materials as visible light cameras because those materials effectively block all of the infrared energy from getting to the detector. This also explains why thermal cameras can’t be used to see through windows.
BASIC PARTS OF A THERMAL SENSOR Detector
Lens
System-on-a-Chip (SOC)
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Lens Flange
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HOW DO I PICK THE RIGHT THERMAL IMAGER FOR MY INTEGRATED PRODUCT? Selecting the right thermal camera will be largely dependent upon what you want the camera to do, and a number of factors play into this determination. WHAT RESOLUTION AND LENS DO I NEED? The answer to this question will be determined by what you need to image, how far away you need to see it, and the level of detail you need in the images. There is a range of thermal cameras from lower-cost imagers that go into smart phones to highperformance cameras that are used for critical, life-saving missions. FLIR cameras like Boson are available in qVGA (320x256) resolution, and VGA (640x512) resolution, and have horizontal fields of view (FOV) ranging from 4° to 92°. Lower-cost solutions like Lepton are available in lower resolutions like 80x60 and 160x120.
There is a range of thermal cameras from lower-cost imagers that go into smart phones to highperformance cameras that are used for critical, life-saving missions.
The camera’s resolution will relate directly to image detail and potential detection range. If you just need to detect an object, a single pixel may be enough to do the job. If you need to recognize what an object is, say, a person, an animal, or a vehicle you’ll need a larger group of pixels. Even more pixels still may be necessary to identify the nature of an object, such as if it’s an armed person, a dog rather than a deer, or a truck instead of a car. Dividing the width of the scene in that FOV by the horizontal number of pixels will tell you the smallest feature that can be detected at that distance. You can also use a specification called the “instantaneous field of view” (iFOV) to get the angular size of a single pixel and calculate its size at a given range as well.
WHAT SENSITIVITY DO I NEED? A camera’s sensitivity is specified as the Noise Equivalent Differential Temperature (NEDT). It’s a signal-to-noise metric that tells you the temperature difference required to produce a signal equal to the camera’s temporal noise, and – by extension – the minimum temperature difference the camera can resolve. NEDT is usually expressed in milliKelvin (mK), with lower numbers indicating superior performance than higher numbers. The FLIR Boson has industry-leading sensitivity of less than 50 mK. Once you’ve thought these factors through, contact our Applications Engineering team; they’ll help you explore your options a little deeper and get the solution you need.
[email protected]
RESOLUTION COMPARISON
10 X 10 PIXELS
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25 X 25 PIXELS
50 X 50 PIXELS
160x120
100 X 100 PIXELS
200 X 200 PIXELS
640x512
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DO I NEED RADIOMETRY OR JUST IMAGING CAPABILITY? All thermal cameras can provide an image of the relative intensities of thermal energy within their fields of view, but some cameras take that a step further and provide calibrated, non-contact temperature measurements of those objects. This is a process called radiometry. In order to do this, the camera needs to compensate for other sources of radiation (reflections, lens materials), atmospheric effects (humidity, weather conditions, and distance to target), and the material properties of the objects being viewed (in particular their emissivity). Once these elements are known, the amount of radiation received by the camera can be converted to a temperature value with accuracy approaching +/-2°C.
Some thermal cameras take imaging a step further providing calibrated, non-contact temperature measurements of objects.
FLIR cameras are available with varying degrees of radiometric capability and accuracy – from imaging only, to a simple center spot meter function, to advanced radiometry and improved accuracy – and many FLIR cameras can be ordered as either imaging or radiometric.
Radiometric images allow you to capture non-contact temperature measurements of every pixel in the image. FLIR Tools Software lets you harness the power of Radiotmetic Images.
Be able to thermally tune a Radiometric image as well
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Change color palettes giving yourself better visibilty depending on temperature variances
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WHAT SHOULD I LOOK FOR IN AN IR SUPPLIER? When you design in thermal imaging, you’re making a commitment to the technology; you need a company that is making a commitment to you as well. Make sure your infrared supplier has a demonstrated commitment in these important areas: • The quality and reliability to ensure your cameras “just work” throughout your product’s designed life cycle • A proven track record of making their OEM partners successful • Dedicated product technical support staff to answer your questions • Local after-sales service
FLIR's commitment to being the world leader in infrared technology makes us the best choice to be your complete and total infrared supplier.
• Quick and easy access to product specs, drawings, and interface documents on the company website or by email • A stable company that will be around for the long haul • A commitment to continuous product development and improvement that will keep them always at the leading edge of technology shifts before they occur • Industry-specific domain knowledge in rapidly-developing areas like security, IoT, and automotive with their specific interfaces, regulations, and controls
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WHAT IS THE TOTAL COST OF OWNERSHIP? There are many important considerations to take into account beyond simple acquisition cost that determine whether or not an OEM thermal camera is a good value. Certainly the unit cost is important, but your total build cost can keep your system from being competitive in the market. Hidden costs like difficult integration, extra engineering development time, and expanded time-to-market can ruin even the best plans to introduce a new product to the market. Make sure you choose a supplier that:
• Has competitive pricing • Provides professional technical support to ease integration • Has readily-available documentation, SDKs, solution accelerators, and access to applications engineers
From longwave to midwave to shortwave IR, FLIR's thermal camera cores are designed for easy and efficient integration into higher level assemblies and platforms.
• Backs their products with industry-leading warranties • Get you to market at a price point that enables you to be successful
Intelligent devices for sensor networks
Software Developers Kit (SDK) Easy discovery, monitoring and command & control of FLIR Systems thermal imaging cameras in new or existing networks. The Software Developers Kit (SDK) is a tool that helps systems integrators to deploy FLIR Systems thermal imaging cameras in large, existing or new, security networks. The SDK will accelerate any application programming with FLIR Systems thermal imaging cameras. If you are a systems integrator that wants to build its own system utilizing thermal imaging cameras for a security application, then the SDK together with FLIR Systems’ thermal imaging cameras will give you a jump start in your task. The SDK will allow you to fully exploit the possibilities that FLIR’s unique infrared camera connectivity technology offers and combine camera functionality with other sensors and detection devices. More and more, TCP/IP networks are being used as a base to build security & surveillance command and control applications. Developed by system integrators, the SDK toolkit allows for “plug & play” installation of FLIR Systems thermal imaging cameras into today’s TCP/IP infrastructures. Drivers for FLIR Systems thermal imaging cameras Thanks to their embedded connectivity technology and the SDK toolkit, FLIR Systems thermal imaging cameras become manageable network nodes for your application. Most of FLIR Systems’ thermal imaging cameras offer Ethernet based plug & play connectivity. The SDK toolkit allows integrators to discover and control multiple cameras and use them from multiple operator workstations on a Commercial of the Shelf (COTS) network. Optional Developer Tools allow integration of active map displays, video monitoring, and VMD or target detection with intelligent video alarms. The SDK libraries are offered for Windows Visual Studio (C, VC++ or VB) and .NET development platforms as well as for different Linux/Unix environments.
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Connectivity to other sensors A security network consists of various types of sensors that need to work together in order to offer maximum coverage. Radar, perimeter and ground sensors, CCTV cameras, thermal imaging cameras and other sensors need to be connected in “slew to cue” configurations. The SDK allows integrators to easily command FLIR thermal imaging cameras to be a slave to other sensors like radars and fences. The SDK toolkit allows for easy integration of all these systems into turnkey applications. New Drivers can be easily built by FLIR Systems to support new customer furnished devices, making them new plug & play elements in their sensor networks. The SDK toolkit allows you to discover and control FLIR Systems thermal imaging cameras, but also many other legacy devices into this network. These devices are controlled by sensor server nodes using serial ports, analog video, TASS or Pelco-D.
Network administration The SDK toolkit allows multiple users to monitor and adjust multiple sensors throughout the security network. Users can remotely position sensors on an IP network and, in real-time, monitor camera video and configure camera field of view, camera tilt angle, focus, sensitivity and contrast. Rules, with variable authority, can be set up to define which user has access to configure or control certain sensors. Thanks to the SDK toolkit the user can mix and match sensors and controllers to the particular application without spending undue effort designing for different scenarios. It also helps with obsolescence management. The SDK is part of a Development Platform that is continuously being updated. Customizable User Interfaces By using the SDK toolkit you can focus on the design of your own user interface to control multiple security sensors or integrate FLIR Systems thermal imaging cameras into existing command and control applications. A sample console is available to demonstrate the SDK capabilities, and use it as reference or test point for your own development. Image post-processing options An optional Windows DirectShow Based Video Player ActiveX grants integrators access to embed advanced image post-processing functions like electronic stabilization. Long range cameras for border protection are often installed on a mast or tower which is susceptible to extreme climatic conditions. Using the electronic stabilization option, the thermal image on your monitor will be stable even when the tower or mast is slightly moving. Other filters, like histogram or look-up tables, can also be inserted to enhance or tune the image on each operator workstation.
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DO THERMAL CAMERAS REQUIRE EXPORT LICENSES? Some do and some don’t. FLIR employs a team of trade compliance professionals that understand the export rules and regulations, and can assist our customers with their export questions and issues. In circumstances where FLIR delivers a camera to a customer in the U.S. who intends to export or re-export the FLIR camera outside of the United States, whether or not the camera is integrated into another product, it is the customer’s responsibility to apply for the required export license from the appropriate department of the U.S. government. To learn more about export regulations surrounding thermal cameras, visit www.flir.com/export.
FLIR is committed to following all export regulations and to making sure we support our customers is doing so as well.
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HEADQUARTERS FLIR Systems, Inc. 27700 SW Parkway Ave Wilsonville, OR 97070 SANTA BARBARA FLIR Systems, Inc. 6769 Hollister Ave. Goleta, CA 93117 PH: 1 805.964.9797 EUROPE FLIR Systems, Inc. Luxemburgstraat 2 2321 Meer Belgium PH: +32 (0) 3665 5100 CHINA - BEIJING FLIR Systems, Co., Ltd. Room 502, West Wing, Hanwei Building No. 7 Guanghua Ave Chaoyang District, Beijing 100004, China PH: +86 10-59797755 www.flir.com/oem NASDAQ: FLIR
Equipment described herein is subject to US export regulations and may require a license prior to export. Diversion contrary to US law is prohibited. Imagery for illustration purposes only. Specifications are subject to change without notice. ©2016 FLIR Systems, Inc. All rights reserved. 09/26/2016 16-0392-OEM-COR
