The current mainstream ones are Gen2 and Gen3.
Resolution is basically a parameter standard for judging the quality of night vision devices of the same level. There is a premise here that they are of the same level. The same level refers to the comparison of night vision devices belonging to the 2nd generation + or 3rd generation. Even the 3rd generation night vision goggles have products with low resolution, and there are several levels of resolution for each level of mid-range night vision goggles. Then the main difference between the 2nd generation + and the 3rd generation night vision device is that the type of cathode tube is different. The unit of parameter that expresses the resolution of night vision goggles is lp/mm, which means line pair/mm. The higher this parameter is, the higher the resolution of night vision goggles.
The SNR is jointly determined by the image enhancement tube and the internal optical path of the night vision instrument. The higher the SNR is, the more anti-interference ability of the night vision instrument imaging is, and the less interference of the internal optical path is, so the noise and distortion of the image are smaller, and the image is clearer. It can also be explained that the SNR value of generation 3 is higher than that of generation 2 +.
Sensitivity
Sensitivity is also the most important indicator to describe the brightness of night vision devices. The higher the sensitivity, the higher the magnification of night vision devices for low-illumination light. Or simply put, the higher the sensitivity, the stronger the night vision boosts the brightness, so in low light, the brightness and contrast of the image are also higher. So the sensitivity reflects the night vision capability of the night vision device.
The FOM is used to evaluate the comprehensive performance of night vision devices.
Magnification, a number used to describe the relationship between the actual size of an object and its magnification. An object at a distance of 700 meters is as large as an object at a distance of 100 meters with the naked eye when viewed through a telescope with a magnification of 7 times. The magnification rate when the night vision instrument sees the target, the general magnification rate is 1X, 3X, 5X, 6X, 7X and so on. At present, most of the night vision devices for single soldiers are double and most of them are head-mounted ones, because they are more conducive to the real and reliable images. If you wear a 5 times power night vision device, it is impossible to judge the real distance between the target and you. High power night vision devices are usually hand-held.
The field of view, takes the lens of the optical instrument as the vertex, and the angle formed by the two edges of the maximum range of the object image of the measured target that can pass through the lens is called the angle of view. The size of the field of view determines the field of view of the optical instrument. The larger the field of view, the larger the field of view and the smaller the optical magnification. The field of view angle is about 40° when the monocular night vision device is doubled, and the binocular binocular is doubled is about 40°. The field of view of the four-eye night vision device currently under development can reach 80°-120°.
Exit pupil diameter
The exit pupil diameter refers to the diameter of the bright spot formed behind the eyepiece after the light rays converge through the eyepiece. For the optical equipment used by the naked eye, the light must pass through the pupil and enter the retina for imaging. The human pupil is about 3 mm in the daytime and up to 7 mm at night. When observing with optical equipment, the bright spot formed by the converging light of the eyepiece will be projected on the pupil. Therefore, the larger the diameter of the exit pupil, the brighter the image will appear. But an exit pupil diameter larger than the pupil diameter is meaningless.
Diopter, a unit of measurement of the refractive power of a lens. Diopter adjustment is to address differences in vision in the eyes.
IR Indicator
IR Indicator are used to enhance close-up viewing at night. Generally, the power is small, and the infrared indicator is built-in, mainly to enhance the concealment when used at night.
When the battery is low, the indicator light is generally red and displayed in the eyepiece. The purpose of this design is also to enhance the concealment during use. In addition, the visor, a soft rubber holster at the eyepiece, is also used to block the light where the eyes are watching during use and enhance concealment.
This parameter usually consists of two parts: aperture value and lens aperture. For example, F1.2, 25mm. F1.2 is the aperture value and 25mm is the lens diameter.
Aperture value, abbreviated as F-number (also called focal ratio). The larger the F-number, the smaller the aperture. Conversely, the smaller the F value, the larger the aperture, the better the light transmission rate, and the clearer and brighter the image.
This parameter corresponds to IP+Arabic numerals, such as IP65, IP67, IP68, etc. The first number 6 refers to the dustproof level, and the second number 5 refers to the waterproof level.
