What is Night Vision?
Night vision enables to operate safely in night and low light conditions. Owning the best night vision equipment on the market will not always provide the best images. Only quality Image Intensifier Tubes (I2Ts) can provide the best night vision images. That’s why it is important, not only to choose a good quality night vision goggle, but to equip it with the best possible Image Intensifier.
What is an Image Intensifier Tube?
An I2T is a device that intensifies (or amplifies) low light level images into levels that can be seen by the human eye. I2Ts collect the existing ambient light from natural sources, such as starlight or moonlight, or from artificial sources such as street lights or infrared illuminators. The light passes through several internal components to multiply the existing light several thousand times, producing a much brighter image that can be seen by the human eye.
Operation in High Light Levels
High light conditions can be steady, such as a full moon, or sudden, such as during or straight after an explosion. Prolonged exposure to high light can be harmful to an Image Intensifier.
Operation in Low Light Levels
Seeing in low light levels is critical to improve situational awareness. The darker it is, the closer the viewer needs to be to detect, recognize or identify any danger. There are two key factors that determine the Image Intensifier’s ability to see in low light: Signal-to-Noise Ratio (SNR) and Gain.
SNR typically defines how much system noise interferes with the image. SNR measurements have been standardized to allow for better comparison. In very simple terms, a higher SNR level is better than a lower one when measuring in similar light conditions. Look for a SNR that offers minimal and typical ratings of 21 or higher.
Gain is defined as the number of times the Image Intensifier amplifies the light. This specification should match the night vision device into which it is interated. If the night vision device has an External Gain Control, providing an Image Intensifier with a greater gain range also provides a more versatile system for the user.
Limiting Resolution is the resolution measured in line pairs per mm (lp/mm), that the viewer can distinguish. Most I2Ts have a limiting resolution between 60 and 72 lp/mm. A higher number in this measurement can produce a sharper image; however, this could be subjective. The Limiting Resolution should be related to Modular Transfer Function.
Modular Transfer Function
Modular Transfer Function (MTF) is the ratio between contrast and resolution across a range of frequencies (line pairs).
This is an inverse relationship; fewer line pairs will produce a high percentage of contrasting resolution, while greater line pairs will produce a poorer one (see images below). A good quality I2T will produce a linear relationship that preserves as many details as possible in a wide range of lighting conditions.
The ability to customize an I2T to the user’s specific mission or operational requirements is critical. Light conditions of an aviator pilot will be different from those of a soldier deep in the jungle or a hunter in mountainous terrain. Most manufacturers offersseveral options in their Image Intensifiers product ranges that can be adapted to suit.
Auto-gating provides added protection from sudden bright light events. This function operates constantly by rapidly and continually switching on and off the I2T to maintain up to 90% of MTF while protecting the I2T and the soldier’s eyes.
Reducing the load on a soldier is a constant challenge. There are also Image Intensifier options that reduces power consumption and weight while maintaining the provision of high quality images. Please contact MSS Defence for the various available options.
Phosphor Screen Colour
Their are various phosphor screens available to create a more realistic image. Phosphor selection is often a personal preference. Users find that alternative phosphor colours provide less eye fatigue and faster recognition. MSS Defence provides several phosphor colour options. Please contact MSS Defence to discuss the various phosphor colour options.
Want to see the current Night Vision range offered by MSS Defence?
We offer a large range of Night Vision Goggles, Binoculars, Combined Day/Night Vision Devices and Monoculars from various world class manufacturers. Visit our online catalogue to see our current range. For custom requirements or if you cannot find what you need in the catalogue you can always take up contact with us.