2. 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
3. • 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 ??
4. (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 .
5. 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.
6.
7. 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.
8. Types of night vision technology:
1. Thermal Imaging :
This technology operates by capturing the upper portion of the infrared light
spectrum , 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 objects
like tress or buildings .
Why are they Glowing ??
: Because Human bodies radiates more heat
9. 2. Image Enhancement :
This works by collecting the tiny amounts of light , including the lower
portion of infrared light spectrum , that are present but may be
imperceptible to our eyes, and amplifying it to the point that we can easily
observe the image
But why picture looks so greenish….???
10. 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-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 . This information is obtained from several thousand points in
the field of view of the detector array.
• The thermogram created by the detector elements is translated into electric
impulses.
11. (Contd…)
• 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.
• The signal-processing unit sends the information to the display, where it
appears as various colors depending on the intensity of the infrared
emission. The combination of all the impulses from all of the elements
creates the image
12. 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 has
the battery built right in.
2. Cryogenically cooled :
More expensive and more susceptible to damage from rugged use, these
systems have the elements sealed inside a container that cools them to
below 32 F (zero C). The advantage of such a system is the incredible
resolution and sensitivity that result from cooling the elements.
Cryogenically-cooled systems can "see" a difference as small as 0.2 F (0.1
C) from more than 1,000 ft (300 m) away, which is enough to tell if a
person is holding a gun at that distance!
13. • Here’s how fart looks likes in Thermal camera…..interesting…!!! But disgusting…!!
14. 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.
15.
16. (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 travel
through the microchannel plate and hit the walls of the channel.
• The electrons then reach a phosphor screen, which causes the phosphors to
release 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 convert
photons of tight energy to electrons
17. Why does every thing looks green in Night-vision goggles ??
Ans :- Even at night, the photons that hit the lens at the front of night
vision goggles are carrying light of all colors. But when they are converted
to electrons, there's no way to preserve that information. Effectively, the
incoming, colored light is turned into black and white. Why, then, don't
night vision goggles look black and white? The phosphors on their screens
are deliberately chosen to make green pictures because our eyes are more
sensitive to green light. It's also easier to look at green screens for long
periods than to look at black and white ones (that's why early computer
screens tended to be green).
19. • 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 .
20. CONCLUSION :
• Night vision is used to locate an object which is 200 yards away
even in moonless , cloudy night
• The original purpose of night vision was to locate enemy targets at
night
• It is mainly used in military purpose as well as navigation ,
surveillance and targetting
21. • IF YOU ANY QUESTION KINDLY JUST GOOGLE IT YOU WILL GET ORIGINAL
ANSWER .
