night vision technology

NIGHT VISION TECHNOLOGY

KOUSHIK.M11311A0541

NIGHT VISION TECHNOLOGY

Contents: IntroductionTypesGenerationsApplicationsConclusion

Introduction

• It is the ability to see in low light conditions.• Humans have poor night vision when compared to

animals• With a proper Night-vision equipment we can locate an

object clearly which is 200 yards(183 m) away even in moonless,cloudy night.• It is originally developed for military use.

Light spectrum

BASICS

Infrared light can be split into three categories Near-infrared (near-IR) - Closest to visible light, near-IR has

wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter(700nm-1300nm)

Mid-infrared (mid-IR) - Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls(1300nm-3000nm)

Thermal-infrared (thermal-IR) - Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns.

Types

Based on the technology used night vision technology is classified into two categories:

1.Image Intensification2.Thermal imaging

• Image Intensification• 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

Image Intensification

• A conventional lens, called the objective lens captures ambient light and some near-infrared light

• The image-intensifier tube has a photo cathode, which is used to convert the photons of light energy into electrons

Image Intensification

• As the electrons pass through the tube, similar electrons are released from atoms in the tube, multiplying the original number of electrons by a factor of thousands through the use of a micro channel plate (MCP) in the tube

• At the end of the image-intensifier tube, the electrons hit a screen coated with phosphors

• The green phosphor image is viewed through another lens, called the ocular lens, which allows you to magnify and focus the image. The NVD may be connected to an electronic display, such as a monitor, or the image may be viewed directly through the ocular lens

Thermal imaging

• 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

Thermal imaging• works on the principle of black body radiation.• A special lens focuses the infrared light emitted by all of the objects in view • which is scanned by array of infrared detector elements and creates a temperature pattern called thermogram.• Thermogram is translated into electric impulses.• These impulses are sent into signal processing unit which translates elements into data for display.

Thermal imaging

Generations

Generation-0:The first military night vision devices were introduced by the German army as early in 1939.The first NVD was ‘Sparrowhawk’ and used by panther tanks.These require a source of infrared (IR) light mounted on or near the device to illuminate the target area.

Generation-1

• Rely on ambient light instead of an infrared light.• A photo cathode is

used which intensifiesthe image around1000 times.• Operating life:

2000 hours• But are bulky, require

moonlight to function properly.

Generation-2

• Used MCP(Micro Channel Plate) there by improving image size and quality. • Works in low ambient

light and even in moonless nights.• Light amplication is

around 20,000 times.

Generation-3

• Used a photo cathode made of GaAs and ion barrier coating on MCP• The ion-barrier film increased

the operational life of the tube from 2000 to 10,000 hours.• Light amplification also

improved to a range of 30,000-50,000 times.

Applications

• Military • Wildlife observation • Surveillance • Security • Navigation • Hidden-object detection.

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 purposes as well as navigation , surveillance and targeting

• the applications of night vision technology is very essential to combat terrorism which is a major problem being faced by mankind