Night vision Report page 1 of 7

CONTENTS

Ø INTRODUCTION Ø WHAT IS NIGHT VISION Ø HISTORY Ø BASICS Ø HOW IT WORKS Ø IMAGE ENHANCEMENT Ø THERMAL IMAGING Ø GENERATIONS Ø EQUIPMENTS Ø APPLICATIONS Ø ADVANTAGES Ø DISADVANTAGES Ø CONCLUSION Ø FUTURE SCOPE

INTRODUCTION

Night vision technology, by definition, literally allows one to see in the dark. Originally

developed for military use, it has provided the United States with a strategic military

advantage, the value of which can be measured in lives. Federal and state agencies now

routinely utilize the technology for site security, surveillance as well as search and

rescue. Night vision equipment has evolved from bulky optical instruments in lightweight

goggles through the advancement of image intensification technology.

The first thing you probably think of when you see the words night vision is a spy or

action movie you've seen, in which someone straps on a pair of night-vision goggles to

find someone else in a dark building on a moonless night. And you may have wondered

"Do those things really work? Can you actually see in the dark?"

The answer is most definitely yes. With the proper night-vision equipment, you can see a

person standing over 200 yards (183 m) away on a moonless, cloudy night! Night vision

can work in two very different ways, depending on the technology used.

• Image enhancement - This works by collecting the tiny amounts of light,

including the lower portion of the 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.

• 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 trees or buildings.

Night Vision approaches

Types of ranges

Spectral range

Night-useful spectral range techniques can sense radiation that is invisible to a human observer. Human vision is confined to a small portion of the electromagnetic spectrum called visible light. Enhanced spectral range allows the viewer to take advantage of non-visible sources of electromagnetic radiation (such as near-infrared or ultraviolet radiation). Some animals can see using much more of the infrared and/or ultraviolet spectrum than humans.

Intensity range

Sufficient intensity range is simply the ability to see with very small quantities of light. Although the human visual system can, in theory, detect single photons under ideal conditions, the neurological noise filters limit sensitivity to a few tens of photons, even in ideal conditions.

Many animals have better night vision than humans do, the result of one or more differences in the morphology and anatomy of their eyes. These include having a larger eyeball, a larger lens, a larger optical aperture (the pupils may expand to the physical limit of the eyelids), more rods than cones (or rods exclusively) in the retina, a tapetum lucidum.

Enhanced intensity range is achieved via technological means through the use of an image intensifier, gain multiplication CCD, or other very low-noise and high-sensitivity array of photodetectors.