1. In an environment with a certain amount of natural light

Low-light night vision device: In an environment with weak natural light such as moonlight and starlight, a low-light night vision device can provide clear and detailed images. It can amplify these weak lights, making the contours, textures and other details of the target clearly visible, and presenting natural colors and contrast, which is similar to our daily visual experience. For example, in an outdoor scene under moonlight, using a low-light night vision device can see the shape of tree branches and leaves, the undulations of the ground and other details just like observing with the naked eye at dusk.

Infrared night vision device (active): Active infrared night vision device forms images by emitting infrared rays and receiving reflected light. In this environment, the clarity of the image may be affected by the reflective characteristics of the target. If the target reflects infrared rays well, the image will be clearer, but if the target absorbs infrared rays or has a low reflectivity, the image may be blurred and dim, and the color of the image of the active infrared night vision device is quite different from the natural scene, usually black and white or with unnatural tones, and the details are not as good as those of the low-light night vision device.

Infrared night vision device (passive): Passive infrared night vision device (thermal imager) mainly displays the thermal information of the target in an environment with natural light. Although it can effectively detect targets with temperature differences from the background, the details of the target, such as texture and color, are not as clear as those of the low-light night vision device. For example, when observing a car in the distance, the low-light night vision device can see the lines of the car body, the license plate number and other details, while the thermal imager can only see the thermal contours of the heating parts such as the car engine, and the details of the car body are blurred.

2. In a completely dark environment

Low-light-level night vision device: Since there is not enough natural light for amplification, the imaging effect of low-light-level night vision device will be greatly reduced, or even unable to work properly, and the image may be very blurry or completely invisible.

Infrared night vision device (active): Active infrared night vision device can work normally, illuminating the target by emitting infrared rays and receiving reflected light to form an image. However, its imaging clarity is still affected by the reflectivity of the target. For targets with low reflectivity, such as black rough objects, the imaging may not be clear enough, but it can generally present the general shape and position of the target in a completely dark environment.

Infrared night vision device (passive): Passive infrared night vision device has a unique advantage in a completely dark environment, and can clearly display the thermal contour of the target object because it is based on the thermal radiation imaging of the object itself. As long as there is a temperature difference between the target and the surrounding environment, the target can be clearly seen, such as finding a hidden person in a dark room or seeing nocturnal animals in the wild. However, thermal imaging images are pseudo-color displays based on temperature differences, and the presentation of physical details of the target, such as patterns and text on the surface of the object, is relatively weak.

To sum up, in an environment with a certain amount of natural light, low-light night vision goggles may provide clearer images with richer details; in a completely dark environment, passive infrared night vision goggles can take advantage and clearly display the thermal profile of the target. The imaging clarity of active infrared night vision goggles is affected by the reflectivity of the target, but they can also work in a completely dark environment.