Last Updated on March 20, 2021
Have you ever needed to see in the dark with night vision goggles? They are really great for targeting enemies or hunting wild beasts. Over time, different types of night vision goggles have developed and their uses are also increasing day by day. Variations of NVGs provide different attractive features that actually make your daily life easier.
Nowadays, when you go for purchasing any quality night vision goggles you will see different options. That’s why you need to learn all of their details to find out the suitable one. So, we’ve decided to explain different kinds of night vision goggles. Let’s get started with the discussion!
Classification of 5 Different Types of Night Vision Goggles
Night vision manufacturers and experts categorize night vision goggles or night vision devices into few types. Each night vision technology has special applications and capabilities. Actually, there are few ways by which we can classify night vision goggles. But we will here discuss the basic types only.
Normally, night vision goggles can be classified into three classes according to their functional dissimilarities. They are light amplification, thermal enhancement, and digital NVGs. But there are few more night-vision goggles types. We will cover all types of NVGs below.
Image Intensifier NVGs
Image intensifier devices are considered the first developed NVDs. Sometimes they are called classical night vision technology also. Usually, they produce black and green images. After long research, the first military night vision devices were used during world war II.
How Do Image Intensifier NVGs Work?
Moon and stars generate infrared lights that human eyes don’t see. These ambient infrared illuminations are used in night vision devices at night. The intensifier tubes of the NVDs amplify the IR lights and convert it into visible light.
The intensifier tubes are considered the main part of the image amplification night vision goggles. This tube has a photocathode at one end, the middle portion has an internal anode, and a phosphor screen on the other end. A high voltage is applied between anode and cathode. So, a strong electric field is produced.
When IR light strikes the photocathode via the front lens, electrons are accelerated by the electric field and emitted toward the phosphor screen and the visible image produces. These are the basics for all image intensification night vision goggles. However, their image clarity, resolution, and performance developed enormously over generations.
Different Generations of Image Intensifier NVGs
The first NVDs were developed in the 1930s and they are developing over periods of time. Night vision goggles generations can be divided into few sections. These are Gen 0, Gen 1, Gen 2, Gen 3, and Gen 4.
The zeroth generation NVGs tubes needed a powerful external IR light source and produced low-resolution dim images. They are considered obsolete and now out of production.
After that, 1st generation’s NVGs have come. These NVDs tubes use ambient lights instead of powerful external IR lights. The images are clearer and brighter in the center than before but distorted in the edges. They are referred to as ‘Starlight’ technology occasionally.
The night vision goggles of Gen II firstly introduced the micro-channel plates (MCP) inside the intensifier tube. These devices enhanced image resolution and gain significantly. These NVGs also reduced size and weight.
In the third generation NVDs, the major advancement was introducing gallium arsenide photocathodes than the earlier generation. They worked great even in the low-light conditions. These devices expected lifetime is approximately 15000 hours.
For better performance, manufacturers introduced ion barrier film Gen 3 NVDs which are sometimes called 4th generation night vision goggles. They produce superb optical clarity images but their manufacturing cost is excessive due to performance improvements.
The Gen 4 NVDs are not recognized yet but some manufacturers level their optics as generation IV NVGs.
Digital Night Vision Goggles
The digital night vision technology is the new technology that has similarities with the Gen 1 NVDs with some additional features. They are cost-efficient NVGs than Starlight devices and provide no distorting images. Also, they offer easier ways of recording and storage. The negative side is that they can’t compete with 2nd gen NVGs and their range is lower than the Gen 1 devices.
Most digital NVGs are equipped with IR diodes with multiple filters that oftentimes provide green, red, or gray shades. The green filters give you images like standard NVGs. On the other hand, red filters are used when need to preserve the night vision. Finally, the gray or neutral filter minimizes the light amounts to the eyes and display black and white images.
How Do Digital Night Vision Goggles Work?
This technology is quite different than the standard NVDs. The light enters into the device through an objective lens then processed in highly sensitive digital devices CCD (charged-coupled devices) or SMOS (complementary metal-oxide-semiconductor) sensors. After that, the signals are sent to the LCD display where you can view the required image.
Infrared Illuminators NVGs
To overcome the limitations of intensifier tubes and digital night vision devices the infrared illuminators NVGs are evolved that incorporate built-in IR illuminators. These IR illuminators NVDs make it possible to improve visibility in cloudy and dark conditions.
Theoretically, any IR light sources such as infrared LED flashlights, infrared lamps, and infrared lasers could serve as IR illuminators. But commercially, LED and laser technologies are used widely for night vision infrared illuminator devices.
Thermal Imaging NVGs
Thermal imaging night vision technology uses distinct technology than the image intensifier or digital NVDs. They detect the heat energy from the target and convert it into the images. Thermal imaging devices can penetrate smoke, fog, and haze.
How Do Thermal Imaging NVGs Work?
Thermal imaging night vision devices complete their image creation processes through a few steps.
- Firstly, a powerful lens focuses on the incoming IR heat radiation from the objects.
- Then, the focused radiation is scanned by infrared detectors ‘phased array’. Thousands of points heat readings are gathered for the field of view within only 1/30th of a second. The detector creates the elaborate “temperature map” called the thermogram.
- After the thermogram is created, it is translated into electric Impulse and sent to the circuit board. The board is called a signal-processing unit, which has also a chip to translate the electric impulse into data for the display.
- Later on, the signal processing unit transfers the data for the display. According to infrared emission, the display shows various colors or shades of the signals. And we can see the thermal images of the objects.
Un-cooled and Cryogenically cooled Thermal Imaging System
A thermal imaging system can be divided into various types. Two common thermal imaging devices are un-cooled and cooled types.
The un-cooled system is the most used type of thermal imaging device. The IR-detector elements are contained in a unit that works at normal room temperature.
On the other hand, the cryogenically cooled thermal system has detector elements that function below zero degrees Celsius but expensive than the un-cooled type. It provides incredible resolution and sensitivity images. This device can see a small difference of 0.1 degrees Celsius from more than 300 m distance.
The un-cooled thermal imaging types are less expensive and good for rough use. But, the cryogenically cooled thermal imaging devices give great clarity images.
Hybrid Thermal-Night Vision Goggles
To incorporate the advantages of both the intensifier tube night vision system and thermal devices a new technology has evolved that is a hybrid thermal-night vision system. These devices actually display the superposition of night vision with the thermal image.
Basically, this technology is still in the early developing stage and few of them are available for law enforcement agencies and military personnel. Few manufacturers refer to these devices as ‘Enhanced Night Vision Goggle-Binocular (ENVG-B)’.
In this article, you have learned different types of night vision goggles with their working principles, advantages, and limitations. Surely, this knowledge will help you a lot while choosing from the varieties of available night vision technologies. Enjoy the great applications of NVGs!