Imager do it yourself. Thermal camera from the camera. Principle of operation of the imager
About such a device as a thermal imager, today, probably, everyone has heard. The exception, perhaps, will be only small children. Another thing is that those who saw this device “alive” are not so many, those who held it in their hands - and even more so. But there are those who not only kept, but created their own "home" version of the thermal imager. However, whatever category you consider yourself, our article will be interesting to you anyway. The uninitiated will be able to understand the principle of operation of the imager, and the experienced and aces will discover new opportunities for themselves. But let's get everything in order.
The device thermal imager, being a device for measuring the temperature of surfaces by a contactless method, can significantly make life easier for representatives of many professions. Originally invented for military purposes, this rather complex and expensive device today is successfully used in most fields of human activity.For example, in industry - to monitor thermal changes during technological processes; in medicine - for the diagnosis of diseases; when hunting for birds and animals; in construction - to identify areas of heat leakage or, conversely, places for laying pipes. And this is not a complete track record of this device.
Types of devices
Thermal imager is so demanded and multifunctional device that it has two technological design options:
- Stationary. Devices in this category are designed for use in industrial plants to control technological processes. The nitrogen cooling system is a fairly frequent fixture with which a similar thermal imager is equipped. The characteristics of its working temperatures are quite impressive: from −40 to +2000 ° C. The basis of these systems are, as a rule, devices assembled on matrices of semiconductor photodetectors.
- Portable (portable). Innovative developments have allowed to move away from the use of bulky cooling equipment, moving to the production of thermal imagers based on uncooled silicon microbolometers.Such devices are inherent in all the advantages of their predecessors, which include, for example, a small temperature step in the measurement (0.1 ° C). It is also possible to use a thermal imager of this class for complex evaluation work, requiring both ease of use and portability of the device. Many portable thermal imagers have the ability to connect to a PC for the rapid processing of data from them.
The use of a thermal imager in a particular area imposes certain prints on the required performance characteristics of this device. Therefore, before purchasing this device, you must evaluate its conditions of use. Will help in this instruction. Thermal imager,acquired without proper familiarization with the rules of operation, it may not fit your needs at all.For example, thermal imagers used in hunting should have a shockproof light alloy body with a degree of protection not lower than IP54.
It is desirable that this was a monoblock design with display on the viewfinder and LCD screen. And the visible range of hunting thermal imagers should reach 1500 m, while in the construction field such requirements are not imposed on thermal imagers.
Principle of operation of the imager
The operation of the imager is based on the ability of any object to generate thermal radiation (IR radiation), the intensity of which directly depends on the temperature of the object. The imager captures infrared rays at large distances, transforming them into a human-readable form. The difference in thermal radiation of various objects and allows you to see the reliefs in the dark, as well as cold or hot streams. In this case, the red color indicates the highest-temperature areas, and black or blue - low-temperature areas.
The fundamental difference between devices such as a thermal imager and a night vision device should be understood. The difference lies in their ability to see in the dark. The imager transmits its own infrared radiation of objects, while the night-vision device reflects and amplified radiation from other objects. That is, it is possible to perform the functions of a night vision device with a thermal imager, but building a heat map using a night vision device does not.
The algorithm of the imager consists of three stages:
- Fixation of infrared radiation.
- Convert it to temperature values.
- Forming a thermogram - a thermal image of an object that displays the temperature distribution on the surfaces of objects.
Moreover, these actions occur instantly.
Despite the rather complicated principle of operation of the thermal imager, the scheme of a portable device is not too cumbersome.
However, it should be borne in mind that for sufficient clarity of the image on the screen requires the presence of special optics, with an admixture of germanium. This is what dictates the high cost of professional devices. Their cost is calculated in thousands, and sometimes tens of thousands of dollars. Agree, rather big amount.
The enormous capabilities of thermal imagers have long inspired many young people to take the idea to assemble this device with their own hands. And, fortunately, there are ways to make a thermal imager with your own hands and avoid such impressive expenses. Of course, if you do not intend to use the device for professional purposes.
Three options for the implementation of the imager at home, we give below - choose which one you like more. And sensors for thermal imagers and other elements of the device can be purchased off-the-shelf.
Option number 1.Thermal camera do it yourself from camera
This method is based on the fact that initially the matrices of all cameras perfectly capture infrared radiation, which, in fact, is necessary for the operation of the thermal imager. Another thing is that photo equipment manufacturers make devices see the same thing as the human eye. To do this, a special filter is placed in front of the matrix, which absorbs or reflects almost all IR radiation - the “thermal mirror” or hot mirror. Thanks to this filter, the matrix sensitivity curve becomes similar to that of the human eye. Therefore, it’s easy to make a thermal imager with your own hands from a camera, you just need to perform two actions - remove the heat filters from the camera and install a visible spectrum filter instead. However, as practice shows, the latter is not always necessary.
Scope of the self-made thermal imager
Is it possible to use a thermal imager made in this way for domestic needs? Is complete. Will such a thermal imager be suitable for construction or, for example, when hunting? Quite possibly.In any case, lovers of outdoor recreation will definitely like such a device. With it, you can control the approach of animals to your camp at night, as well as in fog or clouds of dust to search for the lost members of the group.
If you have an unnecessary SLR at your disposal, about $ 40 for an IR filter, the desire and the ability to disassemble the camera, then you should try this option.
Option number 2. Do-it-yourself thermal imager using an infrared thermometer and Arduino board
The idea of this method is very simple. To create a thermal imager with your own hands, you need an inexpensive infrared thermometer - this is a device that can measure the temperature of a specific point in space at a short distance, and an Arduino board, through which we connect it to RGB-LEDs from a lamp.
The Arduino board is a software and hardware tool designed for non-professional users to build simple systems in the field of automation and robotics.
Let's program the system so that the lamp light is painted in different colors depending on the thermometer readings.We traditionally make the heat match the red color, and the low blue. Thus, directing the flashlight with a built-in thermometer to any object, we automatically highlight this object with the appropriate color, depending on its temperature. If you add a camera to this set, you will not only be able to see the temperature of the surfaces of the objects around you in color, but also get images that are no worse than those that even the most expensive thermal imagers allow you to see.
Where can I use such a thermal imager?
Of course, such devices are not the same as thermal imagers for hunting. It’s hard to make a powerful device with your own hands. But the presented option can be quite useful for domestic needs, especially since the cost of this homemade design does not exceed $ 50.
Option number 3. Improved home-made thermal imager for shooting static objects
The development was born to two German students Max Ritter and Mark Cole. These young inhabitants of the city of Mindelheim invented a rather simple device to manufacture and received an award for it in 2010 at a scientific and technical forum.
The device consists of two servo drives (for horizontal and vertical movement), an Arduino controller (responsible for processing signals and transferring data to a PC), a non-contact temperature sensor module (for example, MLX90614-BCI), a laser module, or a laser pointer (indicating the scanning zone ), enclosures and webcams. You will also need two 4.7 kΩ resistors and a tripod.
The camera plays the role of a peculiar viewfinder of the scanning area, as well as the source of the original image, any cheap webcam can handle this role (the smaller it is, the better).
Data generated by the sensor can be read using SMBus and PWM buses. Our case also allows the use of a sensor with BCI indices. 3V power supply. The BCI index indicates the type of form factor with a nozzle that provides a narrow angle of view of 5 °.
- We place the Arduino board in the case with the battery compartment.
- Fasten the servomotor using superglue or epoxy in the front empty space of the board.
- We place the second servomotor in a rotary device and fasten the entire structure.
- Connect an infrared thermometer to Arduino, connecting for this Ground to GND, SDA to PIN4 VIN to 3.3V and SCL to PIN5. Also install a 4.7 kΩ resistor by connecting SDA to 3.3V and SCL to 3.3V.
- We make a connection to a laser card or laser pointer. This is to keep track of where the scan is currently taking place.
- Install the webcam so that its direction exactly coincides with the direction of the IR sensor and laser.
And that's all. You made a thermal imager with your own hands!
For what will fit
The process of scanning an object and issuing a heat map takes about a minute, because the sensor scans the future image point by point. This, of course, is absolutely useless for the hunting process. However, this self-made thermal imager for construction and other repairs will be a great help. For example, it can be used as a test method for heating electrical connections or power assemblies. The device allows not only to see the thermogram, but also the quantitative values of temperatures.
In addition to the slow operation of the imager has another drawback - a tight binding to the PC, which makes it weakly mobile. But in some cases, the capabilities of the device and its cost are completely justified - for all components you will have to pay no more than 200 y. e.
From the variants of assembly of improvised thermal imagers described by us, two conclusions are suggested:
- It is quite possible to make a thermal imager by yourself.
- The self-made thermal imager has a very narrow scope.
Therefore, if you need a thermal imager for global purposes, it is worthwhile to postpone experiments and spend money on high-quality equipment. Anyone who just loves to design and who is completely satisfied with the possibilities of home-made, you can give advice - collect, experiment, and it may well be that you will be able to outdo the achievements of the self-made options described by us and create much more advanced thermal imagers for hunting with your own hands. Dare!
Those who are not particularly friendly with a soldering iron and a screwdriver, but love to spend time in nature, as well as those who, for professional purposes, can use the visualization of the temperature properties of objects in the range from 0 to 100 ° C, it is recommended to pay attention to the finished semi-professional equipment. For example, on smartphones with a thermal imager Flir One.
These devices may well serve the service of hunters and extreme travelers, as they are convenient, mobile, able to work at temperatures from 0 to 45 ° C and high atmospheric humidity.And at the same time the cost of such a device is not much different from the cost of all sorts of homemade.