When and by whom the Thermal Imaging camera was invented

August 11, 2022

The world we live in is not perfect. And a man in this world is constantly trying to improve it and define his place in it. A place, the top of which only exists in the virtual world. Studying the problem, scientists went to its solution for centuries and, having reached the top, realized that this is only an intermediate point, not a victory. A man without wings always dreamed of flying like a bird. And he flew, having designed an airplane. As he took off into the air, he was horrified - it was only the foot of Olympus. After all, from the plane, he was closer to dreaming about the stars, and the ocean from a height was immense and as unexplored. This only added to the desire to move forward, including to see further, clearer, and better. Seeing, like a cat, in the dark and using someone else's warmth of a living warm-blooded organism to discover a third, virtually real "cat's vision." A vision has opened and is opening up a host of new and unexpected solutions in the development of almost every field of scientific activity. This is just the beginning of a long and endless journey. The path of the study and implementation of infrared, in common parlance, thermal technology, began two centuries ago. In science, there is a complicated-simple designation for radiated thermal energy, defined as the "heat signature." In principle, it's because even if ice emits thermal energy as an object heats in proportion, the release of thermal energy in infrared waves increases, which a snake can sense unmistakably. This is the best example of how this animal, discerning the temperature difference of rodents, successfully attacks its prey in complete darkness. How does it work?

When and who invented thermal imaging
In the early nineteenth century, astronomer William Herschel, while searching for a solution to the problem of reducing the brightness of the sun's image in telescopes, discovered the release of a large amount of heat when using a red filter. When measured, the heat increased in the dark region beyond the red end of the spectrum. When the point of maximum was established, it was found to be far beyond the red end of the spectrum, now known as the "infrared wave range." This discovery he called the thermometric scope. Further research showed that beyond this spectrum, there is an invisible form of light, called "invisible rays," which only seventy years later received the now-familiar name of "infrared." Incidentally, he also obtained the first recording of a thermal image on paper, which he called a thermograph. At the end of the nineteenth century, the American scientist Langley, invented a device - a bolometer, to measure thermal radiation. It was the prototype of today's very sensitive thermometer, which focused infrared radiation onto plates and measured electric current with a galvanometer. At the beginning of the twentieth century, in 1934, the Hungarian physicist Tihanyi invented the electronic television camera sensitive to infrared radiation. This was the starting point for the active development of night vision. Since that time, night vision devices have been divided into generations. The gradual introduction of each generation was associated with increasing the range of observation, improving image quality, and reducing the weight and size of devices. The criterion defining the new generation is the main component of the device - the electro-optical converter, the essence of which is to make the invisible visible by increasing the brightness.
How thermal imaging was born
The start was given by the so-called "zero" generation where an optical converter from the Dutch company Philips was used, named after one of the developers "Holst's glass." The photocathode and phosphor were applied to their bottoms in two nested beakers. By creating an electrostatic field, they achieved image transfer. In fact, in this version, the equipment functioned solely by obligatory illumination of the object of observation with an infrared spotlight. Even though the device was impressive in size, very heavy, and with poor image quality, the British began mass production of it for the army's needs in 1942. In four years of using this converter, active development and production of night sights, binoculars, and systems for tanks and other equipment began. In the sixties, there were attempts to produce single-element detectors that scanned and created linear images of what was seen. Due to the project's high cost, this idea was not realized.
Single-cascade devices of this generation have more disadvantages than pluses. In the first generation of the electro-optical device, a fragile glass vacuum bulb with photocathode sensitivity was used as the main element. This device gave a clear image in the center and distorted everything at the edges. With a side or frontal source of bright light, the instrument practically became "blind." At night without additional infrared illumination, visibility was also almost zero. In the sixties, with the development of fiber-optic technology, it became possible to improve the devices of the first generation, replacing them with a conditional one-plus. The flat glass was replaced by a fiber-optic plate, which made it possible to transmit images with great clarity, obtain high resolution throughout the frame, and eliminate glare.
The seventies were marked by the development of the second generation of devices. American researchers equipped the device with an amplifier based on a microchannel plate, where the electrons in a special chamber are amplified many times, obtaining an excellent vision. Because of this, the second generation of the electro-optical device is commonly referred to as an inverter device.
There is no dispersal chamber in the following second-plus generation, called planar, and the electron enters directly through the electron-optical converter screen. The device lost image quality, and, at the same time, the rate of the image in the infrared mode was doubled. The innovations added brightness control and protection from side and frontal light. These devices belonged to professional equipment.
In 1982 began the countdown of the third generation of electro-optical devices, different in design. They used gallium, which increased the infrared sensitivity by several times. Devices of this generation are recognized as high-tech and are of great interest, first of all, to the military-industrial complex. Due to the absence of a fiber-optic plate, it should be noted that the devices of the fourth generation are not protected from lateral light exposure. And the price. The device in this generation surpassed all reasonable tolerances in understanding the manufacturer's cost formation.
Probably to compensate for the device's disadvantages and reduce the cost, the device of SUPER two-plus generation was developed. The developers planned to combine the technological advantages of all previous generations of the electron-optical converter in this equipment. The result was a very sensitive photocathode. As specialists admit, there is no difference between the Super Two Plus and the third generation. Except for the price. In terms of cost, the Super Two Plus corresponds to the price of an average budget car.
First applications
At the beginning of 1930, German scientists actively investigated the effects of thermal radiation on semiconductors. As a result, sensitive radiation receivers were developed, which played an essential role in developing numerous infrared systems, produced up to four thousand each month, for the military industry. The most successful in the 1930s were the Americans, who created equipment for driving tanks at night and night sights for ships. In 1941 the British navy began to equip vessels with night vision devices based on optical image converters, which helped boats return to their home base in the dark. With their help, boats returning after an attack found the base ship by its signal lights. Almost at the same time, the German army was equipped with infrared equipment for driving tanks at night, night rifle sights, and aircraft identification systems. For example, at night, when using two-hundred-watt headlights on tanks closed with an infrared filter, the driver could see enormous obstacles almost two hundred meters away, and the rifle sight worked effectively up to one hundred meters out. In the early sixties, the Swedish company AGA developed an infrared thermal imager for the military, whose subsequent models for infrared imaging were for many years the best in the world. When the three largest infrared manufacturers, the American companies FLIR and Inframetrics and the Swedish AGEMA Infrared Systems, merged in the mid-nineties, a new phase of thermal imaging began. Today FLIR Systems, an American company, is the world's largest manufacturer of commercial thermal imaging cameras for scientific research, industry, and agriculture, industry and agriculture, airborne object monitoring, and night vision.