BY-

Abhishek Goyal

B.Tech(3rd year)

SEMINAR ON

NIGHT VISION TECHNOLOGY

What is night vision History Working of night vision device Generations Usage References

WHAT I WILL COVER!!!!

WHAT IS NIGHT VISION

TECHNOLOGY?????

The word ‘Night vision’ itself means the ability to see in low light conditions.

Humans have poor night vision compared to many other animals.

INTRODUCTION

So we all might have a question in our mind that is this really possible to see in the dark night?

The answer is……..YES, we can see in the dark night using the proper equipment made by using this technology.

We can see a person standing over 183m(200 yards) away in the dark night.

(Contd…)

Pre 1940’s: Flares and spotlights were used for operations at night.

Due to the nature of these early night vision devices (NVD), they gave away tactical positions.

Military scientists began to think of ways to improve night vision to gain a strategic advantage

HISTORY

Now The Question Arises

HOW DOES IT WORKS??

The night vision is possible because of two approaches:

(1) Sufficient spectral range (2) Sufficient intensity range.

Two technologies are used for night vision: (1)Thermal Imaging (2)Image Intensification

Infrared light is used to visualize the things in the dark.

The amount of energy in a light wave is related to its wavelength: Shorter wavelengths have higher energy.

Of visible light, violet has the most energy, and red has the least.

Just next to the visible light spectrum is the infrared spectrum.

(Contd…)

IMAGE INTENSIFICATION(Light Amplification)

1. It is also called light amplification.2. It is less expensive than thermal 3.Light amplification technology takes the small amount of light, such as moonlight or starlight, that is in the surrounding area, and converts the light energy (scientists call it photons), into electrical energy (electrons)4. These electrons pass through a thin disk that's about the size of a quarter and contains over 10 million channels. As the electrons travel through and strike the walls of the channels, thousands more electrons are released. 5. These multiplied electrons then bounce off of a phosphor screen which converts the electrons back into photons and lets you see an impressive nighttime view even when it's really dark.

THERMAL IMAGING

1.A special lens focuses the infrared light emitted by all of the objects in view.2.The focused light is scanned by a phased array of infrared-detector elements. The detector elements create a very detailed temperature pattern called a thermogram. It only takes about one-thirtieth of a second for the detector array to obtain the temperature information to make the thermogram. 3.The thermogram created by the detector elements is translated into electric impulses. 4.The impulses are sent to a signal-processing unit, a circuit board with a dedicated chip that translates the information from the elements into data for the display. 5.The signal-processing unit sends the information to the display, where it appears as various colors depending on the intensity of the infrared emission. 6.The combination of all the impulses from all of the elements creates the image.

NVDs have been around for more than 50 years. They are categorized by generation.

Each substantial change in NVD technology establishes a new generation.

GENERATIONS

Created by US Army. Uses active infrared. A projection unit called IR illuminator is

attached with NVD. Use anode in conjunction with cathode to

accelerate the electrons. Problems : acceleration causes distortion of

image and reduction of the life of the tube.

GENERATION-0

Uses passive infrared. Uses ambient light provided by the moon and

the stars. Doesn’t work well on cloudy or moonless

nights. Uses same image-intensifier tube technology

as Generation-0. Same problems as faced by the Generation-0.

GENERATION -1

Offer improved resolution and performance over Generation-1 devices.

Considerably more reliable. Able to see in extreme low light conditions

due to the addition of microchannel plate(MCP) to the image-intensifier tube.

The images are less distorted and brighter.

GENERATION-2

Currently used by the US Army. Better resolution and sensitivity. Photocathode is made up of Gallium Arsenide-

efficient of converting photons to electrons.Tube life is increased

GENERATION-3

Shows significant improvement in both high- and low-level light environments.

No ion barrier in MCP. Reduced background noise. Enhances signal to noise ratio. Images are less distorted and brighter.

GENERATION-4

It can be splitted in three broad categories:

ScopesGogglesCameras

NIGHT VISION DEVICES

SCOPES

GOGGLES

CAMERAS

Military Hunting Wildlife observation Surveillance SecurityHidden-object detection Entertainment

APPLICATIONS

An increase in nighttime situational awareness for pilots.

This would markedly decrease the possibility of collisions with terrain or man-made obstructions.

It does permit the user to see objects that normally would not be seen by the unaided eye.

ADVANTAGES

Lack of color discrimination. Neck strain and fatigue. High initial cost to purchase. Require on-going maintenance. Need for recurrent training. Decreased field of aided view .

DISADVANTAGES

.

BMW's Night Vision with Pedestrian Detection

system allows drivers to see what (or who) is

down the road -- even on the darkest nights.

SECURITY PURPOSE

http://en.wikipedia.org/wiki/Night_vision

http://electronics.howstuffworks.com

REFERENCES