Something for the development, industry or for a smartphone? 320x240pix. or 160x120pix is sufficient? We will give you answers to the most frequently asked questions, parameter specifications, and specific product recommendations by the type of measurement.
This is an archive article published 09.05.2018. Some information may no longer be up to date and in line with the current state. Please contact us in case of interest.
Selecting a new thermal camera is just like buying a new regular camera. They have very similar patterns, technologies and the logic of the whole concept. We use thermal camera to take pictures, make videos – same as with the regular camera. Today, many of us use a smartphone for a fast and relatively high-quality photo, but professionals will appreciate the so-called "reflex camera".
What is a thermal camera and related science, infrared thermography and thermogram?
Infrared thermography It is a new science discipline that deals with the analysis of the distribution of the temperature field on the object surface in a contactless manner. The role of the thermography is the analysis of the infrared energy emitted from an object. The thermographic measurement system can display the temperature field of the measured object, but only on its surface.
Thermal cameras They allow you to see the infrared radiation of the object so that it can be seen (visualization). The output from the thermal camera is the infrared picture. It is called thermogram. Radiometric thermal cameras allow the user to determine the temperature at each point of the thermogram. However, determining the temperature is not easy. It depends on several parameters. One of the main parameters is object emissivity. The ideal black object has emissivity 1, polished objects have a very low emissivity (up to 0.1).
Thermogram Or infrared image is an image created by a thermal camera. Infrared radiation is invisible to the human eye, and therefore thermal images are visualized using the pallets that assign colour to different temperatures (different amount of heat flux). The same image can be thus displayed in different colour pallets to highlight other places.
How to select the best thermal camera?
Time goes forward and it is more than good to have an overview of how to make things easier or even leave it to tools or machines. The thermal camera will help you here for sure. Before we start breaking down the technical parameters, two basic things need to be clarified: 1. What I’m going to use the thermal camera for? Selecting the application is the most important part. Do I work on electronic device installations, on device development, or on PCBs? 2. What it should and can bring to me? If we already know, which purpose the thermal camera will serve, we will share some information thanks to which you can choose the best thermal camera for your needs.
Shape and design ideal for work The standard thermal camera is held in one hand, secured by a strap on the hand or attached to the tripod. The selection is huge. Wallet size model, with fixed base, durable industrial thermal cameras or miniature models combined with a smartphone. Some models bring more transporting practicality, another more stable solution.
Distance from the measured object, resolution and temperature range The most important technical parameters are: - Distance from the measured object (in meters), - sensor resolution (in pixels), - temperature range ( in °C), in which we want to measure.
The most frequently used applications are:
- measurement of air conditioning units or heat loss in buildings,
- measuring on the electrical switchboard,
- measuring on the PCBs with SMD components.
Air-conditioning units or buildings: Most of these are large devices, from the perspective of today's "mini-electronics", so it will be enough to measure a few meters away from the device. The temperature will be around the room temperature and the resolution requirement is lower than in the other applications listed below. Plus, it's easy to handle the device.
Measuring on the electrical switchboards: At first glance, there are larger and smaller elements, parts (hereinafter referred to as objects). It is simply not possible to determine whether large or small objects have to be measured for longer or shorter distances. It will require something universal. From the temperature point of view, it is possible to find destructions of the given objects or shortcuts in the switchboard. We think that in this case we can get 100° C or even more. A very valuable feature is the resistance to eventual fall and resistance of the device as such.
Measuring on the PCBs with SMD components: Detail and sensitivity are parameters number one. Sharp focus of the SMD component of 1x0.5 mm is a difficult task, but it’s not impossible. The measurement will not take place on more than 20cm, unless we want to target the entire PCB. The current values are not in tens of Amps like at the switchboard, so the short circuit will not be so dramatic. But the temperature can reach 100° C even in this case. Again, the large plus is a stable base with the possibility of fixed PCBs and thermal camera.
Simple, basic distribution: Sensor resolution: The resolution determines how many pixels will the given object capture, i.e., the more pixels, the greater the image accuracy and the quality of the measurement. The subject of resolution, pixels, aspect ratios may be known to us from the areas of video quality or TV selection. The resolution is typically from 80x60 pixels to 640x480 pixels in a 4:3 ratio. Good resolution for quality images is from 160x120 pixels.
3 groups of resolutions:
80x60 pix., 120x90 pix. basic class
160x120 pix., 220x165 pix., 240x180 pix. middle class
260x195 pix., 320x240 pix. and 640x480pix. professional class
Common resolution can be improved by Super-resolution. It is a software version for professional thermal cameras. All the listed resolutions can be found on our website.
Temperature range: The range ranges from minus temperatures (-25 ° C) to several positive temperature levels. In our e-shop you will find thermo cameras at a positive level from + 150° C up to + 1200° C. If we divide these temperature ranges into groups, we have again 3 groups:
up to 250° C base class
up to 650° C middle class
up to 1200° C professional grade
Distance from the measured object, fixed or manual focus: Focal length is typically 0.15m or 0.45m in basic thermal cameras with fixed focus. With manual focusing, this distance can be set manually (in the same way as for lenses). For high-end thermal cameras, these lenses can be purchased:
- Macro lens for the measuring on processor, - wide-angle lens for measurement in hard-to-reach places or - 2x or 4x zoom telephoto lens for measuring off-grid electricity distribution (in a distribution system).
Fixed focus - Basic class
Manual focus 0.15-0.45m - Medium class
Interchangeable lens and manual focus on each of them- Professional class
Angle of view: This parameter is closely related to the focal length. The larger the focal length, the smaller the angle of view is. The angle of view is inversely proportional to the distance from the measured object. We are on a scale from 24° up to 55° vertically. We can fundamentally change this value by a series of lenses.
Sensitivity: One of the main parameters for detailed measurements. The theory says: "The temperature sensitivity expresses the smallest temperature differences on the surface of the black body that the thermal camera can record. The higher the sensitivity, the more accurate the measurement is. " This parameter is in proportion to the resolution value chosen by the manufacturer, so it is not necessary to fundamentally deal with it for the initial selection. It is not as decisive as a resolution or temperature range.
Emissivity: Emissivity is the optical feature of a material that describes how much light was emitted from the material in relation to the amount emitted by the black body at the same temperature. The black body is the ideal body that absorbs all the radiation. At the same time, it is also an ideal radiator - the radiation of the black body is maximal and depends only on temperature. The spectral distribution of the intensity of the black body radiation is given by Planck's law. The emissivity is set on the thermal camera manually. In both, basic and professional thermal cameras, there is no difference. (Emissivity table)
Sharing your work and other features: In addition to the high quality result of your measurement, it is necessary to think of the whole application also from the point of view of the "outside the thermal camera". How will the image be processed? Does this result need to be sent to customers? "Do I work in the development and want to see the results in real time on my PC"? All of the above questions can be implemented to achieve effective work. Všetky vyššie uvedené otázky možno realizovať a docieliť tak efektívnu prácu. List of PC software: Fluke Connect Fluke SmartView Flir Tools Flir Tools+ and others
Air-conditioning unit or buildings: A suitable product from our offer is Flir C3. It offers a resolution of 80x60 pixels and a temperature range of -10° C ... + 150° C. The focal length is 1m MSX from the measured object, fixed lens. An advantage is the touch screen, easy control, the size of this device, WiFi for connectivity in combination with FlirTools PC-based image processing software. The competition is Flir One Pro. With smaller structure and parameters it leads over Flir C3, but after saving the thermographic image to a PC, it can no longer be processed. Other application areas: solar panels, storage humidity, heat dissipation, heat distribution for solid fuel boilers and others.
Basic line Temperature range: -10…+150°C Resolution: 80x60 pix. Lens: Fixed, non-replaceable Other: Touch screen, Wi-Fi, Flir Tools
Why do we recommend? - Small size and weight 130g - Resistance - Wi-Fi + Flir Tools
Measuring on the electrical switchboards: It is universal. Golden mean. Fluke TiS 45 is the first thermal camera with manual focus in this category. With this device, you can easily handle, for example, electrical current distribution, mechanical parts heating control, engine control. The lens is non-replaceable.
Middle line Temperature range: -20…+350°C Resolution: 160x120 pix. Lens: Manual, non-replaceable Other: Fluke Connect
Why do we recommend? - Universal for any measurement - Manual setting of focal length - Extensive accessories including factory calibration
Measuring on the PCBs with SMD components: For detailed measurements, you will definitely need solid base or a tripod. The Flir ETS 320 delivers great results at a distance of several millimetres. Because of its stability, there is no blur in the final picture. With this thermal camera, you will also appreciate the real-time tracking along with the record. Therefore, it is suitable for applications where we monitor the temperature of the measuring device at a certain time after it is switched on (temperature changes on the PCB and their interaction with each other).
Middle-professional line Temperature range: -20…+250°C Resolution: 320x240 pix. Lens: Manual, non-changeable Other: Flir Tools, real-time tracking
Why do we recommend? - Fixed base - Image directly on PC in real time, tracking backward - Not dependant on batteries
The biggest mistake when selecting and operating the thermal camera:
It is not a mistake to take a more powerful device for not too specific measurements. The mistake is if you choose a device with basic parameters for more demanding applications. You would surely not use your VGA camera mobile phone at a photo competition. Therefore, we do not recommend you to measure SMD parts with the basic class of thermal cameras as you will not achieve satisfactory results. Another mistake is the measurement of glass or extremely smooth and glossy surfaces. Here, the user can measure himself with the thermal camera in his hand (image reflection). If the thermal camera is intended to be used to measure these surfaces, it is appropriate to blacken or otherwise roughen the object. If this is not possible, we do not recommend such technology (thermo vision).
For the first experience with the thermal camera, we recommend that you invest at most in the middle class of the thermal cameras. Consider a lot more parameters than just the resolution or the temperature range when selecting the right one for you.
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Date of publishing 09.05.2018 When you issue article on your website, please give its source: http://www.soselectronic.com/articles/sos-supplier-of-solution/how-to-properly-select-a-thermal-camera-2148