Introduction: In the "reconnaissance-strike" kill chain, the application of sensor night vision technology can greatly enhance the situational awareness of the all-weather battlefield and create tactical advantages. Which one is the "fire eye" in night battles, low-light enhancement or thermal imaging? Why can thermal imaging technology, which was once only used for high-end applications such as military, flood into the civilian market?
1. The "third eye" of night battles
From ancient times to the present, battles often start at night. Using night vision technologies such as low-light enhancement and infrared thermal imaging, combat troops can break through the obstacles of the night and gain the freedom of night battles. Soldiers, tanks, ships, aircraft and other equipment equipped with night vision equipment can greatly extend the effective combat time.
1) Low-light enhancement and amplification
Low-light night vision devices have become the most widely used type of night vision devices by the military of various countries because of their simple principles, good image quality and low cost. Basically, they are all based on the third and fourth generation tube low-light night vision technology, such as the mainstream night vision devices AN/PVS-31 and GPNVG-18 of the US special forces using the third generation film-free white phosphorus intensified tube; the LUCIE night vision devices equipped by the French, German and other European armies are all low-light night vision devices.
Low-light night vision devices are also called image intensification technology, which is actually to enhance and amplify the tiny light source electronic signal to make it visible. In an extremely low-brightness environment, the image intensifier can be used to illuminate the object with weak light such as moonlight and starlight or emit infrared detection light. The light reflected by the object is amplified by the image intensifier and converted into an image that can be clearly observed by the human eye, thereby realizing the observation of the target at night. Therefore, the image intensifier tube is a key component of the low-light night vision device, and its quality directly determines the effect of the night vision device.
Low-light night vision devices are certainly easy to use, but the effect is not very good when used in cloudy days, dark or smoky conditions. At this time, the more advanced infrared thermal imaging night vision device comes in handy.
2) Ubiquitous infrared thermal radiation
Light is an electromagnetic wave. Our naked eyes can only see the world between 400-600nm in the electromagnetic wave. Humans lack the visual ability to perceive temperature. The non-visible light with a wavelength between 760-1000nm is called infrared (IR). In our lives, whether it is biological or mechanical, even ice, it will emit heat energy, and the wavelength of thermal radiation is in the infrared band.
Similar to the camera imaging visible light, the thermal imager is a device that images infrared rays. It passively receives radiation from the target and does not actively send out signals. According to the different intensities of infrared rays radiated by different objects, the thermal imager is first used to obtain the thermal radiation information of the target, and the target object is identified based on the difference in infrared rays radiated by the target object and the background object.
The real advantage of thermal imaging lies in target observation and recognition. As long as the surface emissivity of the target is different from that of the background, or the target has its own temperature, thermal imaging can easily distinguish the target through the temperature difference. For example, in the woods, although thermal imaging can only see the treetops that are blurred, it is very easy to see all animals within a range of more than 100 meters. Even if they are covered by grass or other things, as long as there is a little shadow, the user can find them. Infrared and low light are difficult to do.
3) Super CP-composite night vision solution
Of course, thermal imagers are not omnipotent. Since they rely on temperature difference imaging, the image contrast is low, and the target cannot be seen clearly through obstacles such as glass.
Thermal imaging also has its own disadvantages compared to infrared low light. Thermal imaging relies on the surface temperature of the target to distinguish the target, and the surface temperature is affected by the surface material of the object. The emissivity varies greatly. If a large number of objects with very small surface temperature differences are piled up in the picture, thermal imaging is difficult to distinguish, which will cause the picture to be blurred. For example, it is usually difficult to distinguish the details of grass and tree canopies on the ground with thermal imaging. If you only rely on thermal imaging to move at night, it is easy to be fooled on the rugged ground.
So the composite night vision device that integrates low-light night vision goggles and infrared thermal imaging has come on the scene. Take the fourth-generation AN/PVS-21 binocular night vision device of the United States as an example. Its dual lenses enable it to have two optical channels, which can superimpose the infrared imaging and low-light imaging of the target after processing. Even in a completely dark environment, it can see the infrared image of the heat source emitted by the enemy through the camouflage.
