Night vision technology

WELCOME TO SEMINAR ON

: BY RABINATH JHACSE

DEPARTMENTROLL NO:33

CONTENTS :

1. INTRODUCTION

2. BASIC KNOWLEDGE

3. INFRARED INFORMATION

4. TYPES OF NIGHT VISION TECHNOLOGY

5. THERMAL IMAGING

6. TYPES OF THERMAL IMAGING

7. IMAGE ENHANCEMENT

9. APPLICATIONS

10. ADVANTAGE

11. CONCLUSION

• Night vision is the ability to see in low light conditions. Whether by biological or technological means

• Humans are built for living in the daytime and sleeping in the dark. The retina (the light-sensitive part of our eyes) has cells called cones (for seeing colored light) and rods (for detecting movement and dim light). We have 20 times more rods than cones (120 million rods and only 6 million cones), yet we're still not very good at seeing in the dark.

But why we can’t see in night ??

(Contd…)

• Some animals are built differently , They have much bigger pupils (holes in front of their eyes) to let in more light.

• Now question is can we see at night…?? Answer.. is yes we can see in night using proper equipment .

• Night-Vision is mainly developed for military use .

• With a proper Night-vision equipment , we can see over 200 yards (183 meters) on a moonless , cloudy night .

Let’s get some basic information :

• 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.

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

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

Infrared light can be split into three categories :

• Near Infrared (near-IR) :

Closest to visible light, near-IR has wavelengths that range 0.7 to 1.3 micron

• Mid-infrared (mid-IT):

Mid-IR has wavelengths ranging from 1.3 to 3 microns.

• Thermal-infrared (thermal-IR):

Occupying the largest part of the infrared spectrum , thermal-IR has wavelengths ranging from 3 micron to over 30 micron

Both near-IR and mid-IR are used by a variety of electronic devices , including remote controls.

Types of night vision technology:

1. Thermal Imaging :

This technology operates by capturing the upper portion of the infrared lightspectrum , which is emitted as heat by objects instead of simply reflected as light.Hotter objects , such as warm bodies, emit more of this light than cooler objectslike tress or buildings .

Why are they Glowing ??

: Because Human bodies radiates more heat

2. Image Enhancement :

This works by collecting the tiny amounts of light , including the lowerportion of infrared light spectrum , that are present but may beimperceptible to our eyes, and amplifying it to the point that we can easilyobserve the image

But why picture looks so greenish….???

THERMAL -IMAGING :

• Here's how thermal imaging works:

• A special lens focuses the infrared light emitted by all of the objects in view.

• The focused light is scanned by a phased array of infrared-detectorelements. The detector elements create a very detailed temperature patterncalled a thermogram . It only takes about one-thirtieth of a second for thedetector array to obtain the temperature information to make thethermogram . This information is obtained from several thousand points inthe field of view of the detector array.

• The thermogram created by the detector elements is translated into electricimpulses.

(Contd…)

• The impulses are sent to a signal-processing unit, a circuit board with adedicated chip that translates the information from the elements into datafor the display.

• The signal-processing unit sends the information to the display, where itappears as various colors depending on the intensity of the infraredemission. The combination of all the impulses from all of the elementscreates the image

Types of thermal imaging :

1. Un-cooled :

This is the most common type of thermal-imaging device. The infrared-detector elements are contained in a unit that operates at room temperature.This type of system is completely quiet, activates immediately and hasthe battery built right in.

2. Cryogenically cooled :

More expensive and more susceptible to damage from rugged use, thesesystems have the elements sealed inside a container that cools them tobelow 32 F (zero C). The advantage of such a system is the incredibleresolution and sensitivity that result from cooling the elements.Cryogenically-cooled systems can "see" a difference as small as 0.2 F (0.1C) from more than 1,000 ft (300 m) away, which is enough to tell if aperson is holding a gun at that distance!

• Here’s how fart looks likes in Thermal camera…..interesting…!!! But disgusting…!!

IMAGE –ENHANCEMENT :Here’s how image enhancement works :

• Image enhancement starts when the objective lens gathers and amplifies infrared and visible light and conveys it to the image intensifier tube.

• This tube is powered by N-cell or AA batteries and produces ab0ut 5,000 volts to the components of the image intensifier tube.

(Contd…)

• The electrons then pass through the microchannel plate , which is a thin disk .Having over ten million channels, this works as an electron multiplier.

• The process of cascade secondary emission then occurs as the electrons travelthrough the microchannel plate and hit the walls of the channel.

• The electrons then reach a phosphor screen, which causes the phosphors torelease photons due to the energy given off by the electrons.

• After the last step, the phosphor image can be seen through the ocular lense conveying a green, magnified, and focussed image.

• After that , the image-intensifier has a photocathode that is used to convertphotons of tight energy to electrons

Why does every thing looks green in Night-vision goggles ??

Ans :- Even at night, the photons that hit the lens at the front of nightvision goggles are carrying light of all colors. But when they are convertedto electrons, there's no way to preserve that information. Effectively, theincoming, colored light is turned into black and white. Why, then, don'tnight vision goggles look black and white? The phosphors on their screensare deliberately chosen to make green pictures because our eyes are moresensitive to green light. It's also easier to look at green screens for longperiods than to look at black and white ones (that's why early computerscreens tended to be green).

APPLICATIONS :

Military

Law enforcement

Hunting

Wildlife observationSurveillance

NavigationHidden-object detection

Entertainment

Space exploration

• Distant vision is possible .

• Detection of objects in absolute darkness .

• Less affect by temperature variation .

ADVANTAGES :

OPTIONAL : you can caught the person who farts frequently .

CONCLUSION :

• Night vision is used to locate an object which is 200 yards awayeven in moonless , cloudy night

• The original purpose of night vision was to locate enemy targets atnight

• It is mainly used in military purpose as well as navigation ,surveillance and targetting

• IF YOU ANY QUESTION KINDLY JUST GOOGLE IT YOU WILL GET ORIGINAL ANSWER .