How to choose the night vision device suitable for your needs
Are you planning to purchase a night vision device?
You do not know what will best suit your needs?
Do you doubt between prismatic viewfinder, monocular or glasses?
The light intensity
The light intensity is measured in lux. I put some case examples and measurements:
-for the day can be measured about 10,000 lux.
-in a closed room illuminated (office) 500lux.
-A area with low illumination would be about 10 lux.
With full moon will have 0.1 lux and the colors are not distinguished
‘In a dark night with no moon we just 0,001 lux.
Light are small particles, photons. Less light less photons. The human eye can become accustomed to low light but can not fully see. At dusk the eye needs help to see. This is where the displayed night vision.
The intensifier tube
Devices that have intensifier tube are able to capture these photons useless to the human eye, including infrared light as the stars. These devices intensify and amplify light.
The front optic collects light and focuses on the tube where a photocathode converts the photons to electrons, which are amplified and projected on a phosphor screen which emits visible light that we see. The projected image corresponds to the input. Phosphorus is green because the color is better for the human eye distinguishes and less fatiguing.
The number of times the machine amplifies the light is called gain and depends on the ability of the photocathode to convert the most sensitive photons and its ability to acelearlos and represent them on the screen.
The buyer of a night vision equipment should be set at the total profit .
Generations in night vision
The tubes can be of different sizes, shapes and there are four generations available.
-GEN 0 GEN 1: Create an electrostatic field and acceleration of photons. Gen 0 always needgo, while Gen 1 amplifies light. A common feature is that remain lit for a short period after extinguish because they maintain the load.
-GEN 2 and GEN 3: These go out immediately and are smaller. They use a microchannel plate to improve gain and resolution. His photocathodes are equal in Gen 3 it is upthree times more sensitive although its use in situations with residual light can provide images with few contrasts. It is in rural areas where the latter take your entire party.
As you go up the scale in gain and intensifier tubes is significantly improved its performance , but also a notable increase in price .
You can read the complete information of all generations at the end of article.
As assessing the performance of a team
Before we must be clear evaluate a number of questions, what do we need to see? How far? How many light?
-The teams Gen1 may be sufficient for non – professional use for applications such as night with moon and short distances.
If there is no moon is most recommended equipment Super Gen 1+ or 2+ Gen to SuperGen or HyperGEN.
The factors to consider when buying are:
• photosensitivity (uA / lm) – is the team’s ability to convert photons into electrons. The higher the better.
• Gain -Unless more and more need more distance. We need to know the gain of the entire team. Much profit is important in remote locations and away from stocks.
• Scope – The effective range depends on the system gain, the resolution increases the lens and ambient light.
• Image quality and resolution – good resolution can even identify people or animals long distances.
• Ergonomics – size, weight and ease of use.
• Distortion – Only Gen 2 and Gen 3 produce an image without appreciable distortion thanks to the microchannel plate.
• Time of Use – If you need to look a long time followed is very convenient to use glasses or binoculars. Monocular vision tired a lot.
• Weatherproof – Most teams put up a moderate rain but if you want to use in bad weather or marine environment need military specifications.
• Confidence – With proper care most modern equipment give no problems in years. It is especially important not to subject the tubes at high exposures of light.
More information about generations (source: airelibre.com)
Generation 0 – usually uses a photocathode S-1 with a peak response in the green-blue area and a sensitivity of 60 uA photo / lm. They are based on creating a strong electrostatic field to accelerate electrons. This type of tubes rather distorts the image and always need help IR light emitted.
Generation 1 – usually uses a photocathode S-10 or S-20 with photosensitivity 120-200 uA / lm. They are based on creating a strong electrostatic field to accelerate electrons. Being much more sensitive to the first do not always need the help of IR (see more than the naked eye) are.
The Gen 1 have power supplies high voltage distortion at the edges and decent behavior in low light. The tube keeps some charge and still see a few seconds after turning it off. Tube gain is usually in 100-500x with a resolution of 25-30 lp / mm although some manufacturers put higher figures. They consume a large amount and frequently spots are normal look. The tubes manufactured in Russia and Belarus account for 95% of the market. Normal life is about 1,000 hours.
CF Super / Super Generation 1+ – Yukon are pipes produced by incorporating a fiber optic faceplate in front of the tube (not MCP) reducing distortion at the edges and can reach resolutions of 42 lp / mm in the center. Normal life is about 1,000 hours.
Generation 2 – normally uses a photocathode S-25 (near infrared) with a photosensitivity of 240-350 uA / lm with a microchannel plate (MCP) to increase the gain. Gen 2 tubes already have a sufficient performance for use in image recording and photography and its distortion is small. They have automatic gain control, glare protection and the same resolution at the edges than in the center. The resolution in the center varies between 28 to 32 lp / mm and are most suitable for urban areas that Gen 3. The signal / noise ratio (SNR) is 11 typical and typical lifetime of 2,000 hours.
Generation 2+ – Based on Gen 2 technology, they are more sensitive to the photocathode. 350-450 uA / lm. The resolution in the center varies between 32-40 lp / mm. The typical signal / noise ratio (SNR) is 13 and the typical lifetime of 2,000 hours.
SuperGen – Based on Gen 2 technology, they still have more sensitivity in the photocathode. 500-600 uA / lm. The resolution in the center varies between 45-54 lp / mm. The signal / noise ratio (SNR) is typically 18 to 21 and typical lifetime of 10,000 hours.
HyperGEN – is the highest quality based on the Gen 2 technology, with an even more sensitive photocathode. 600-800 uA / lm. They are now available with the “autogating” option for better performance in variable light situations. The resolution in the center varies between 55-78 lp / mm. The signal / noise ratio (SNR) typically is 20-28 and the typical lifetime of 15,000 hours.
Generation 3 – Use gallium arsenide for the photocathode and microchannel plate. You can exceed 800 uA / lm in the region from 450 to 950 nm. Tubes are very high sensitivity and a long life, with little distortion. The resolution in the center ranges from 45 to 64 lp / mm (substantially lower than the best HyperGEN). The signal / noise ratio (SNR) is typically 18-28 and the typical lifetime of 10,000 to 15,000 hours.
Generation 4 – NOT EXIST. Some dealers say they have tubes fourth generation but there is no such technology. Gen 3 tubes are with “autogating”.