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 1.
How does night vision work?
2.
What is the difference between Generation 1, 2, and 3 night
vision devices?
3.
How to tell Gen. 2 (or 3) from Gen. 1 device: Quick 'rule
of thumb':
4.
Can night Vision equipment be used in daytime?
5.
Why do I see some black or white spots in the viewer?
6.
Why do all night vision have a small magnification?
7.
Is Night Vision Legal?
8.
Will it make me blind if I look at a bright object ?
9.
I have heard it is unsafe to look into the Infra Red illuminator.
Is it so?
10.
What type of laser do your Laser Range Finders Use?
1. How does night vision work?
The objective lens collects weak ambient light that you
cannot see with your eye, and focuses it on the photocathode
of the image intensifier tube (IIT). The intensifier amplifies
the light by many hundred or thousand times and projects
the image on the screen. The eyepieces optics brings this
projection to viewer’s eyes.
2. What is the difference between
Generation 1, 2, and 3 night vision devices?
Generations refer to technological peculiarities that lead
to difference in performance. Since its appearance, night
vision has developed in the direction allowing people to
see better and sharper image at lower light levels. The
technological leaps on that way are called Generations.
Contemporary market comprises the following main gradations:
Gen. 1 (consumer quality products), Gen. 2 (obsolete technology,
widely spread in 80s, but still present for economical reasons),
Gen. 2+ and Gen.3. The main parameters of advanced Gen.
2+ systems are equivalent to those of Gen.3. The main difference
between these two is in their behavior in different light
environments. Gen. 3 provides the best visibility in extreme
darkness, while Gen. 2+ is better suited for the mid-level
lighting. The three main criteria are System Light Gain,
System Resolution, and Signal-to-Noise Ratio (SNR).
System light gain indicates how many times a night vision
unit amplifies the available light.
Tube Resolution
deals with the image quality. This parameter evaluates the
sharpness and clarity of the  amplified image.
Signal-to-Noise
Ratio shows the ratio between signal and noise components
on the display.
Sometimes night vision devices are compared by the Figure
of Merit (FOM) parameter. FOM is calculated as System Resolution
(SR) multiplied by Signal-to-Noise Ratio (SNR). (FOM=SRxSNR).
The best Gen.3 devices available on the market have FOM
of 1400-1600.
| Specifications |
Gen.
1
|
Gen.
2
|
Gen.
2+
|
Gen.
3
|
| Image
Intensifier Light Amplification |
100-500
|
20,000-30,000
|
20,000-30,000
|
20,000-30,000
|
| Signal-to-Noise
Ratio |
-
|
12-15
|
15-25
|
15-30
|
| Resolution,
lp/mm |
25-30
|
30-68
|
45-68
|
45-68
|
| FOM |
-
|
<750
|
750-1200
|
800-1600
|
3. How to tell Gen. 2 (or 3) from
Gen. 1 device: Quick 'Rule of thumb':
Turn off the unit. If it shuts off immediately, it is a
Gen. 2 (or 3) unit. If the image fades slowly during certain
a period time, it is a Gen. 1 unit.
4.
Can night Vision equipment be used in daytime?
NEVER expose the opened objective lens of an active unit
in daytime.During
the day, caps must cover objective lens.
There
is a tiny hole in the cap to provide enough light for daytime
operation. The unit may be turned on during daytime but
the lenses must be protected against the light. NEVER aim
an active unit at intense light sources (i.e. lights, headlamps,
campfires, the moon, etc.). This may damage the image intensifier.
5. Why
do I see some black or white spots in the viewer?
These are the cosmetic blemishes in the image intensifier,
which do not affect the performance or reliability of a
night vision device. A certain number of such spots of varying
sizes are inherent in the manufacturing processes.
They
can also be dirt or debris between the lenses, which should
be removed by careful cleaning if the system is designed
with interchangeable optics.
6. Why do all night
vision have a small magnification?
Consider the distance you need to look through and the overall
area you are observing or searching. For most surveillance
or search applications, the higher the magnification or
narrower the field of view, the more difficult it is to
scan the area to avoid missing important objects or events.
Usually a 1:1 lens with a 40° field of view provides
optimal performance. For long-range observation or weapon
sight applications, the magnification number will vary.
However, be sure to consider the other performance characteristics
of the device. As the magnification increases, the field
of view decreases, reducing the amount of light captured.
Consequently, you will need an image tube with better performance
at very low-light levels and/or big high-performance lenses.
All these considerations limit the night vision magnification.
It normally does not exceed 2x for the first generation
devices and 4-5x for the second and third. The long-range
observation models also exist on the market. However, these
models are very heavy, bulky, and expensive. The average
magnification of such models is about 10x.
7.
Is Night Vision Legal?
In USA - yes, for all devices. Possession of a night vision
device conforms to Federal Firearms Regulations, as of February
1993. However, use of a weapon sight for hunting may be
limited or illegal in your state. Check with local authorities.
In addition, you are not allowed to export night vision
in any way, even in your personal luggage. The violation
of this rule may lead to serious consequences, including
criminal prosecution.
In all countries other than USA - you must check with the
local authorities what is allowed and under which conditions.
Newcon Optik is not responsible for possession or use of
our equipment, if it is illegal in your country.
8. Will it make
me blind if I look at a bright object ?
This can happen only in movies. In real life, all of our
devices have automatic brightness control. The unit will
adjust the output according to the incoming light, and will
shut itself off if necessary.
9.
I have heard it is unsafe to look into the Infra Red illuminator.
Is it so?
There is some real basis to this rumor. Many military night
vision devices utilize lasers in their illuminators, and
some of them might not be eye-safe. Most of our products
use low power infrared diodes, identical to the ones used
in TV remote controls. Such diodes are absolutely safe.
Certain models of our powerful illuminators and aimers are
not eye-safe. We always warn our customers when the device
can be potentially harmful.
10. What
type of laser do your Laser Range Finders Use?
Most of our Laser Range Finders utilize a Class 1 eye-safe
laser. Only one model, LRB20000A (20 kilometers) incorporates
a Class 3 laser, which is NOT eye-safe.
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