3. INTRODUCTION
HUMAN VISION IS COMPACKED TO VISIBLE RANGE.
ELECTROMAGNETIC SPECTRUM .
ENHANCED SPECTRAL RANGE TECHNIQUES USES
TO VIEW INVISIBLE THINGS.
ENHANCED SPECTRAL RANGE ALLOWS THE
VIEWER TO TAKE ADVANTAGE OF NON-VISIBLE
SOURCES OF ELECTROMAGNETIC RADIATION
5. IMAGE ENHANCEMENT
COLLECTS THE TINY AMOUNTS OF LIGHT .
INCLUDES THE LOWER PORTION OF THE
INFRARED LIGHT SPECTRUM .
AMPLIFYING IT TO THE POINT THAT WE
CAN EASILY OBSERVE THE IMAGE .
6. THERMAL IMAGING
CAPTURES THE UPPER PORTION OF THE
INFRARED LIGHT SPECTRUM.
IR EMITTED AS HEAT BY OBJECTS INSTEAD
OF SIMPLY REFLECTED AS LIGHT .
8. INVENTION OF NIGHT VISION
“SEEING WITHOUT BEING SEEN” IT IS THE BASIC TACTIC
OF ANY MILITARY FORCE IN THE WORLD.
NIGHT VISION SERVES FOR THAT PURPOSE.
NIGHT VISION DEVICE INVENTED BASICALLY FOR
MILITARY USE.
SCIENTIFIC / CIVILIAN USE SOMETIMES LIMITED OR
EVEN FORBIDDEN BY LAW
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9. HISTORY / FUTURE OF NVDs
1930’S - IMAGE CONVERTER TUBE – Basis for NVDs
LATER NVDs WERE CLASSIFIED AS PER THE
DEVELOPMENT STAGE OF USED IMAGE INTENSIFIER
TUBE (IIT) , AS GENERATION OF NVD
GENERATION 0,1, 2, 2+, 3
GENERATION 4 (ONLY IN US)
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10. SPECTRUM OF NVDs
NIGHT VISION MONOCULARS/ BINOCULARS
NIGHT VION WEAPON SIGHTS
NIGHT VISION GOGGLES
LONG RANGE NIGHT VISION
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14. HOW NIGHT VISION WORKS
AN OBJECTIVE LENS (CONVEX TYPE) FOCUSING AN IMAGE INTO A
VACUUM TUBE WITH A PHOTOCATHODE AT ONE END
IT RELEASES ELECTRONS BY THE PHOTOELECTRIC EFFECT ON THE
INCIDENCE OF INCOMING PHOTONS.
FROM THERE, THE PHOTOELECTRON IS ACCELERATED THROUGH
AROUND 5000 VOLTS INTO A TILTED MICROCHANNEL PLATE.
THE HIGH ENERGY ELECTRON RELEASES SOME MICROCHANNEL PLATE
ELECTRONS, WHICH FURTHER RELEASE OTHER ELECTRONS, IN A
PROCESS CALLED SECONDARY CASCADED EMISSION.
THE MCP IS TILTED TO ENCOURAGE MORE ELECTRON COLLISIONS
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15. FOM
FIGURE OF MERIT OF A NIGHT VISION DEVICE
IT’S A MEASURE OF THE QUALITY OF THE IIT
FOM= RESOLUTION X SIGNAL TONOISE
RATIO (S/N)
GEN 3 – APPROX 1600 FOM
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18. GENERATION 0
SO LITTLE, LOW LIGHT AMPLIFICATION
ADDITIONAL IR –ILLUMINATORS MUST BE USED
FOR OBSERVATION.
(THAT’S WHY , THEY ARE CALLED ACTIVE NIGHT
VISION DEVICES )
IMAGE CONVERTER TUBE WAS USED, NOT THE
IMAGE INTENSIFIER TUBE.
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Cont …
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19. Cont …
• S-1 photocathode, coated with
silver shifted cesium oxide
• Anode cone, ensures over high
voltage acceleration focusing and
turning the image up-side-down
• P1 phosphor screen, coating out of
zinc and cadmium transferred
phosphor
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20. GENERATION 0 -DISADVANTAGES
HAD A VERY DISTORTED PICTURE
SHORT TUBE LIFE DUE TO THE HIGH ELECTRICAL
VOLTAGE.
HEAVY AND BIG
POWER SOURCE
AN AUTOMATIC
PROTECTION OF
THE PHOTOSENSITIVE TUBE
DOES NOT EXIST
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21. GENERATION 1
1
IMAGE INTENSIFIER TUBE USED FOR THE ST TIME (WITH MULTI -
ALKALI PHOTO CATHODE - S-20, coating from potassium, sodium,
cesium, silver)
LUMINOUS GAIN BETTER THAN GEN. 0
(P-20 phosphor screen)
SERVICE LIFE OF GEN 1 IIT- 1000-2000 HRS
NO AUTOMATIC PROTECTION AGAINST BRIGHT LIGHT
WORKING RANGE 750-800 nm OF IR WAVE LENGTH
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22. Cont …
Sectional view Gen1, singlestage NVD, low gain
Sectional view Gen1, 3-stage
NVD, generally high gain at low
contrast
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23. GENERATION 2
MICRO CHANNEL PLATE (MCP) USED IN IIT
INSTEAD OF ANODE CONE.
PRINCIPLE CHANGED FROM
ACCELERATION MULTIFICATION (electrons)
THE LIFE SPAN INCREASED TO APPROX. 2500 -
5000 H
WORKS WITHIN THE RANGE BETWEEN 780 AND
850 NM WAVELENGTH
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25. ADVANTAGES OF
ND
2
GEN NVD
NO IR-ILLUMINATOR NEEDED
SMALLER IN DIMENTION
LOW IN WEIGHT
LIFE SPAN OF IIT - 2500- 5000 HRS
AUTOMATIC BRIGHTNESS CONTROL (ABC)
HIGH IMAGE RESOLUTION THAN EARLY GENs.
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26. GENERATION 2+
(SUPPER GEN)
MORE IMPROVED MCP
OVER 4 MILLION MICRO CHANNELS
PHOTO CATHODE-MORE SENSITIVE TO IR
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27. GENERATION 3
NEW COATING FOR PHOTO CATHODE – Ga As
(Gallium Asernic)
IMPROVED IMAGE RESOLUTION
6-12 MILLIONs OF MICRO CHANNELS IN MCP
AN THIN ALUMINIUM LAYER ON THE PC (ION
BARRIER) IS USED FOR AN ENHANCED SERVICE LIFE
SPAN OF IIT- 10000 HRS
IR WAVE LENGTH- 780-920 µm
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28. GENERATION 4
FILMLESS OR THINFILM TUBES IS USED
ONLY USED BY US ARMED FORCES
15000 HRS OF LIFE SPAN
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40. MAINTENANCE
SHOULD NOT OPERATE AT BAD WEATHER
MUST NOT OPERATE AT DAY TIME
KEEP NIGHT VISION BINOCULER CLEAN
CLEAN LENS WITH 99% ETHIL ALCOHOL
SHOULD NOT DROP DOWN
SHOULD NOT COLLIED WITH ANYTHING
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41. Contd.
MUST NOT APPLY GREAS OR OIL ON LENSES
THE N/V BINOCULER HAS TO BE IN THE
CARRING CASE WHILE MOVING/TRANSPORT
REMOVE THE BATTERY BEFORE STORED.
STORED IT AT COOL /DRY PLACE.
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42. Night vision devices are dependent on every
little light information available
The task of the objective lens to collect as much
as possible light and to focus an image on the
image intensifier tube's input window
Tube can strengthen only the low light passed
and collected by the objective lens
Appropriate tuning between the optical and
electronic part should be take place
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