Night Vision Guide
What is Night Vision?
Night Vision is the ability to see in low light conditions. Humans have very poor night vision so they rely on the use of night vision devices such as monocular, binoculars and scopes to get illuminated images at night time which is not visible to the naked eye. There are two types of night vision technologies; Digital Night Vision and Thermal Imaging Night Vision.
Pulsar Helion 2 XP50 Pro Thermal Monocular
Digital vs Thermal Night Vision
Digital Night Vision: A digital night vision device converts a regular optical image into an electrical signal through a CCD or CMOS image sensor. The sensor collects incoming light through its pixels, which is enhanced several times, then the pixels are given a digit value by the sensor and is converted into an image that is generated on an LCD or OLED display that is built into the eyepieces. Now a night vision image can be viewed through the eyepieces.
SiOnyx Aurora Black Colour Night Vision Monocular
Thermal Imaging: Thermal imaging night vision display images that highlight heat signatures of objects. It works through the use of an infrared sensor that identifies differences in temperature and heat signatures of targets which is then translated into a viewable image on an OLED screen. Objects that have high heat signatures glow yellow, orange and red colours, but may be altered based on the colour palette that is used.
Guide TN450 LRF Thermal Night Vision Binoculars
Pros of Digital Night Vision
- Digital night vision is generally more affordable than thermal night vision devices.
- Digital night vision devices are very durable as the intensifier tube and CCD sensor wear slowly over time ensuring they have an extended lifespan.
- Produces a more natural image compared with thermal imaging
- Can be used to see through glass.
Cons of Digital Night Vision
- Cannot see through smoke as the quality of the display will drop and devices will have trouble identifying objects that our camouflaged.
- Users may experience slight lag when an electrical signal is being converted into an image as the signal needs to be refreshed if there is a moving target.
- When there is no natural light, digital night vision devices will rely on infrared illumination to aid sight. This drains the battery rather quickly.
- Needs a light source to form an image.
Pros of Thermal Imaging
- Thermal imaging devices can detect differences in heat as small as 0.01°C.
- Performs exceptionally in harsh weather conditions. Thermal night vision devices operate in harsh conditions and can detect heat signatures in heavy rain, dense fog, dust and smoke. They can be used in complete darkness.
- Can detect heat from warm blooded animals, land, rocks, vegetation and even inanimate objects that emit heat such as engines and machinery.
- Does not require and light to form images allowing you to use them virtually at any time of day.
- The image quality on thermal devices are far better the digital night vision due to its highly powerful sensor which increases detection and detail recognition.
- Longer detection range than digital night vision
Cons of Thermal Imaging
- Thermal night vision devices are far more expensive than digital night vision due to the advanced technology they use which drives up the cost of production.
- Cannot capture images through water or glass. If you are trying to look out a window with a thermal device, you will only see your illuminated reflection.
- Thermal imagers are heavier than digital night vision devices and even regular scopes, binoculars and monocular, which can hinder your ability to perform certain tasks well.
Popular Digital Night Vision Devices Popular Thermal Imaging Devices
Common Uses for Night Vision
Digital Night Vision:
- Law enforcement and security personnel use digital night vision devices to identify persons/objects in the dark as well as observe their actions.
- Surveillance cameras come with digital night vision technology making it great for security.
- First responders use digital night vision for night-time search and rescue operations.
- Hunters use digital night vision to identify trophies while hunting at night.
- Thermal imaging devices are great for general purpose use. They can be mounted on cars to give drivers clear vision when driving through mountainous and forest areas, detecting heat signatures of lost pets and outdoor activities such as hiking at night time.
- Firefighters use thermal night vision for helping them to detect fires, highlighting the most intense and hottest spots and areas which are not safe to enter. These devices are able to see through smoke, therefore, making them very reliant in these situations to keep Firefighters safe.
- Law enforcement can rely on thermal imagers to identify people of interest in low visibility situations. They can also identify heat signatures given off from concealed weapons as well as being useful for tracking during pursuits.
- With the ability to detect small temperature differences, thermal imaging night vision devices will effectively detect targets in harsh weather conditions such as heavy rain and fog making them perfect for hunters. In addition, thermal imagers have long detection ranges due to their digital zoom capabilities and superior optics with some devices achieving ranges up to 1800 meters.
To summarise, digital night vision uses a CCD or CMOS sensor to collect an incoming light source through its pixels in order to covert it into an illuminated image, whereas, thermal night vision uses an infrared sensor that identifies differences in temperature of an environment and translates it into a viewable image. Both types of night vision allow you to see in low light conditions, however, only thermal imaging devices can operate in complete darkness and produces better quality images. They are valuable tools for law enforcement, hunting, search and rescue operations and outdoor activities.
When shopping for a night vision device, there are a few specifications you will need to consider as they determine which device suits you best. The specifications are as follows:
Colour Palettes: Thermal imaging devices come equipped with a range of different colour palettes to view an object more effectively. Each different palette is optimised for specific tasks. For example, White Hot and Black Hot can be used for detection, Ultramarine is best for recognition and Sepia is suited for observing targets for a long period of time.
Detection range: Refers to the distance at which an object can be identified. It is determined by the size of the objective lens and the variable magnification options.
Field of View: Refers to the width of area you can see through an optical device. For night vision devices it is represented in degrees, meaning the angle of view the lens allows one to see.
Frame rate: This refers to the rate at which the pixels on the display of the thermal imager refreshes per second. A frame rate of 50Hz will ensure the image of a moving object is smooth and does not have lag.
NETD: Noise Equivalent Temperature Difference measures thermal sensitivity by highlighting the smallest of temperature differences you can see through your thermal imaging device. The lower the number of the NETD the better it is at spotting the differences in temperature. For example, a thermal imager with a NETD of 25mK (millikelvin) performs better than one with a NETD of 50mK.
Pixel interval: The range of wavelengths that the sensor of the thermal imaging device can detect which is measured in microbiometers (µm). It directly influences bass magnification, image quality and thermal sensitivity which determines how well small differences in temperature is detected. The lower the number of the pixel interval the better the quality of the image will be.
Sensor Resolution: The resolution of the thermal sensor determines the image quality of the device. The higher the resolution is, the clearer and sharper the image will appear. A resolution of 640x480 will yield a better quality image than a resolution of 320x240.