The biggest difference between night vision and thermal imagers is that their working principles are different: thermal imagers convert invisible infrared energy emitted by objects into visible thermal images, and night vision devices actively receive through an image enhancement system. The light source, the night vision device must have an external light source illuminated on the object and reflected to the night vision device before it can be imaged.
The principle of thermal imager:
In layman's terms, a thermal imager converts the invisible infrared energy emitted by an object into a visible thermal image. The different colors on the top of the thermal image represent the different temperatures of the object being measured. By viewing the thermal image, you can observe the overall temperature distribution of the measured target and study the heating of the target. All objects above absolute zero (-273°C) emit infrared radiation. The thermal imager uses an infrared detector and an optical imaging objective to receive the infrared radiation energy distribution pattern of the measured target and reflect it on the photosensitive element of the infrared detector to obtain an infrared thermal image, which is related to the thermal distribution field on the surface of the object. Corresponding.
The principle of night vision:
The night vision device actively receives the light source through the image enhancement system. The night vision device must have an external light source reflected on the object to be received by the night vision device before imaging. Night vision devices focus existing ambient light (starlight, moonlight or infrared light) through the front lens. This light, composed of photons, enters a photon cathode tube, turning the photons into electrons. The electrons are then amplified to larger numbers through electronic and chemical processes. The electrons are then projected onto a screen, turning the magnified electrons back into visible light, which can be seen through the eyepiece. First of all, the most obvious difference between thermal imager and night vision device is that the thermal imager image display is square, and the night vision device image display is circular
The difference between night vision and thermal imaging cameras
1. The effect is different
1) If you have used an ordinary night vision device, you will find that the observation experience of the night vision device and the ordinary infrared thermal imager is completely different. This is because the general night vision device directly observes the target through the lens, so the field of view seen is the same as that seen by the telescope lens, which is circular, and the picture is green. If the clarity is sufficient, it is possible to identify who the target of the character is, and to see the facial features of the person clearly.
2) The infrared night vision thermal imager sees the image on the internal LCD screen instead of directly seeing the target, so the field of view seen is all square. The imaging of the infrared night vision thermal imager will be based on the temperature distribution. The higher the temperature, the brighter the brightness. On the contrary, the color will be dim when the temperature is low.
2. The influence of light factors is different
1) The second-generation night vision device is greatly affected by the environment due to the imaging principle. Especially the effect of light, when the light is dimmed, the observation distance will be shortened. In the case of complete darkness, the auxiliary infrared light source must be used, and the distance of the auxiliary infrared light source is generally only up to 100 meters. At the same time, it is also afraid of strong light, although many traditional night vision devices have strong light protection. However, if the ambient brightness changes greatly, it will have a great impact on the observation.
2) Infrared thermal imaging night vision device will not be affected by light. Whether it is day or night or rainy, snowy, foggy, the target object can be clearly observed. It is for this reason that the top car night vision devices, such as Mercedes-Benz and BMW, use infrared thermal imagers.
So what are their advantages and disadvantages?
The night vision device can identify the target at night and determine the appearance of the target. The thermal imager can only be used to identify the target and determine what the target is from the outline. The thermal imager can view the upper area from the image
Divide true and false goals. Thermal imagers can use passive imaging in total darkness, are not afraid of strong light, and can image through smoke. Night vision devices require active light source intervention to image, cannot penetrate smoke, and are afraid of strong light.