First of all it is necessary to take into account the purpose and conditions at which the NVD will be used as well as its price.

What is the purpose: tourism, animal observation, security of dwelling, solution of safety issues, etc.? Under what conditions, at what light exposure will the observation be conducted? Will it be near cities where there is a background of electric illumination, twilight, moonlight, starry sky, or cloudy sky? If it is the latent observation, it is necessary to keep in mind that there is no opportunity to use the infra-red illuminator. Also it is necessary to take into account the background on which the object will be observed. For example, the person in a camouflage will be more difficult to detect against the background of green wood than against the background of any building.

The NVD with 2 + and 3 tube generations satisfy a requirement for the most difficult conditions of observation. They can be effectively used even at the cloudy sky without additional illumination. These NVD give high and uniform resolution on the screen that allows to see fine details of objects as well as higher comfort of observation. They give the greatest range of observation.

In many cases, especially if there is no necessity for the latent observation when it is possible to use infra-red illumination, near cities where there is a background of electric illumination the NVD on the basis of the 1- st generation tube or on CCD matrixes will be effective. The price of these devices in some times lower than of the devices on 2 +, 3 tube generations.

When choosing, it is necessary to pay attention to magnification and lens aperture. The more the lens magnification, the more range of detection is. But it is on the condition that with increase of magnification there was kept high lens aperture. For example, with 6-times magnification and lens aperture of 1:2, the range of detection will be less than with 4-times magnification and lens aperture of 1:1,5.

In some cases in the image transmitted by the tube, black dots are visible. It is difficult technologically to make image tube without black dots. As a rule, in field conditions presence of these dots practically does not influence on the image quality.

Weight, mechanical characteristics and ergonomics of NVD play a significant role. The NVD should be convenient and reliable especially at long work with it. Therefore not always when purchasing NVD it is not reasonable to take as a basis small weight. Weight is an important characteristic, especially at continuous using of the device. But the aspiration to lower weight, for example, of sights, less than 1 kg, not deteriorating other characteristics, is rather problematic and it is unreasonably expensive.

The high-quality optics without which it is impossible to realize potential characteristics of the image tube is multilens system forming the most part in weight of the device. In view of that many sights are developed for use at impact loads > 500g, structurally the case, mechanical connections, optics, system of adjustment should provide reliability of work of the device as a whole. It is optimum complex solution of requirements to all characteristics of NVD that would define their weight. For example, high-quality professional sight F7000 of firm ITT, USA, with magnification of 4Х, weighs 1,7 kg, and it was developed by highly professional experts.

Various materials are used for manufacturing of NVD cases: light alloys of aluminum, carbon-filled plastics or various kinds of plastic. But it is necessary to draw attention that cases of such devices as binoculars, goggles, sights should be made of strong materials which exclude deformations. These are light alloys of aluminium. You can also use carbon-filled plastics.

NVD are made with a various degree of protection against water and dust. It is necessary to take into account when using the NVD in conditions of tropical and marine climates.

The comfort, efficiency, convenience of using NVD are provided by design and ergonomics. The controls taking into consideration the usage of devices at night should be easily accessible and structurally convenient.

One more important characteristic of NVD is an interpupillary distance. It changes from 58 up to 72 mm. Such devices as binoculars and goggles are usually provided with mechanical separation of the left and right parts. SPF "Dipol" Ltd. produces binoculars and goggles with complex and qualitative optics with an exit pupil of 13 mm. It allows using devices without additional adjustment of interpupillary distance that improves efficiency, convenience and operational reliability.

You should also take into account the price of the NVD that basically depends on the type of the image tube, optics and case materials used. A cheap monocular in plastic case with plastic optics and an image tube of the 1-st generation can cost up to 200 dollars on the US market. A monocular with the1-st generation tube made in solid case and with high-aperture optics will cost 1,5-2 times more. A high-quality monocular with the 2 + generation tube will cost 1000-1500 dollars, and with the 3-rd generation tube will cost more than 3000 dollars.

It is also necessary to consider the professional level and experience of the manufacturer. Some of the manufacturers for advertising purposes exaggerate actual characteristics of the NVD.

The concept of SPF "Dipol" Ltd. in developing of the NVD

SPF "Dipol" is on the market of NVD for more than 17 years. The firm has wide experience in development and manufacture of the NVD, knowledge of buyers' needs and level of technics on the basis of which it is possible to optimize such consumer properties of the NVD as the price and quality. Highly skilled science employees in the field of marketing and optoelectronics are engaged in this process

SPF "Dipol" develops and makes all kinds of NVD such as monoculars, goggles, binoculars, sights with the use of 1, 2 + and 3-rd generation tubes and on CCD matrixes.

For all devices only fast optics with a relative aperture of 1:1,0 (F = 27) up to 1:1,5 (F = 100) is used. The optical circuit used in goggles, monoculars, binoculars of night vision of manufacture SPF "Dipol" Ltd. is developed so that you can easily, without additional adjustment, change the objectives fixed in the devices, with another, receiving thus various optical magnification.

In goggles D2MV SL, D2MS, D221H, binoculars D212 SL, D216 the eyepieces with a big diameter of pupil are used. It allows using operatively the given devices without additional operations and waste of time for installation of the interpupillary distance as well as it you gives comfort at object observing.

All devices made on the 1-st generation tubes have a built - in IR-illuminator and electronic protection from external bright exposure that increases reliability and operating life.

The goggles and monoculars of night vision are fixed on the convenient helmet - mask which allows making various actions for a long time with goggles or monocular, fixed on the head. You can move, do repair work and, etc. A light, convenient, universal helmet - mask provides fast, reliable and convenient fixation of the device on the head. Its design allows to adjust effectively the position against eyes as well as it provides its fast throwing-over with fixing in vertical position.

The NVD on the firm are developed in view of optimization of all characteristics such as optical, mechanical, weight, ergonomics, convenience and reliability in operation. The use of alloys of aviation aluminium gives reliability and durability of devices in operation.

By separate orders there made the NVD for work in difficult climatic conditions, taking into account the qualifying standards of special equipment.

SPF "Dipol" Ltd. in developing of the devices of night vision is guided by the following principle: applying the advanced scientific achievements to create the original devices of the night vision which optimally satisfy demand of users at economically sound prices.

Excellent design, perfect ergonomics, small weight, high-aperture optics, high reliability, universality. It is the device for businessmen. It is optimum relationship of the price, quality and consumer demand.