2. Introduction:
• Night Vision is the ability to see in low light conditions. Whether by
biological or technological.
• Humans have poor night vision compare to many animals because the
human eye lacks a tapetum lucidum.
• Now there are so many technologies which makes humans to see in
night time.
3. How animals see in Dark:
• Humans are bult for living in day time and sleeping in the dark.
• The Retina has cells called cones and rods.
• We have 20 times more rods than cones.(120M rods and 6M cones)
• So we can not see in dark but animals have more cones than us
• Animals also have tapetum lucidum in their eyes. So they can see in
dark
4. Whats makes humans enable to view objects:
• When a light projects on any object reflects the light. this reflected
light by the object enables humans to view the object.
• With this humans are able to distinguish the objecs from others
with respect to it's properties like colour,size,shape,etc.,
5. How it works:
• There are mainly two types of night vision technologies
They are :- 1.Image intensification(low light imaging)
2.Thermal imaging
6. 1.Image intensification(low light imaging):
• Today the most popular and well known method for performing night
vision is based on the use of image intensifiers
• In this image is in green colour because usage of phosphorus
• There are 3 lenses in the intensifier
• An objective lens focuses available light on the photocathode of an
image intensifier
• The light energy causes electrons to be released from cathode which
are accelerated by an electric field to increase their speed
• These electrons will hit phosphorus screen, the energy of electrons
makes the phosphorus glow
7. • A green phosphor is used in this applications because humans
eyes can differentiate more shades of green than any colour
8. Advantages:
• Excellent low light level sensitivity
• high resolution
• low power and cost
• ability to identify people
Disdvantages:
• this meyhod is not useful when there is essentially no
light
• Possibilty of blooming and damaging when observing
bright sourses under low light conditions
9. Thermal Imaging:
• This night vision method do not require any ambient light at all
• They operate on the principle that all objects emit infrared energy as
a function of thier temperature
• in general the hotter an object is the more radiation it emits
• The thermal imager is a product that collects the infrared radiation
from objects in the scene and creates an electronic image
• in addition they are also able to penetrate obstracts such as smoke,
fogg and haze
10. • There are two types of thermal imageing detectors. cooled and Uncooled
• Cooled IR detector camera require cryogenic cooling and uncooled IR
detecor camera are normally either temperature stabilised or entirely
unstabilised
11. Advantages:
• Highest possible thermal sensitivity
• Ability detect people and vehicle at great distances
• Not effected by bright light sources
• Able to perform high speed IR imaging
Disdvantages:
• Expensive to purchase and to opperate
• limited cooler operating life time
• Bulky
12. • These night visions technologies are using by our army to find
enemies in boarders and wars
• It's also used in CC TV's
• Hunting and wild life observation
• Now these are also used in cars for navigation
USES:
