The Digisight Ultra N455 has an external 940nm IR illuminator.

What is an IR Illuminator?

Digital night vision has become a popular tool when hunting hogs, varmint and predators at night.

What is an Infrared (IR) Illuminator?

Infrared devices are used to emit infrared light into the invisible light spectrum but can be seen by special sensors. Though there are multiple IR illuminator forms, digital night vision commonly uses IR LED lighting. True IR illumination is only visible when used with special image sensor tubes and digital night vision devices. IR illuminator output wavelengths vary, resulting in either a visible red glow at the light source or are completely stealth. IR illuminators are beneficial for traditional and digital night vision devices because they provide additional artificial light to better illuminate targets and extend the device’s viewing range.

How Do They Work?

An IR Illuminator helps detect targets at longer distances at night.
An IR Illuminator helps detect targets at longer distances at night.

The infrared illuminator’s output power is measured by its wavelength and valued in nanometers. Nanometers are used to specify the wavelength of the IR that is the visible part of the light spectrum. It is always important to understand the light source’s nm strength—the greater the number, the higher the wavelength. IR illuminators may have the option of variable power or brightness level where the output source may be managed. In these modes, the lens area features a focus diopter to adjust the output’s beam for longer ranges.

Digital night vision devices may include a built-in IR illuminator or a removable one. For example, the Pulsar Digisight Ultra N455 offers a removable IR. Built-in IR illuminators are specifically designed for the device at hand. Often, lower-powered magnification optics feature a weaker illuminator while higher-powered magnification optics boast a stronger IR. It is advised not to view targets at close ranges with a high magnification night vision device with a built-in high-powered infrared illuminator because it will perform poorly—a high-powered IR can blur your image. Buying a separate IR illuminator allows you to make brightness adjustment to avoid this problem.

Use of an external illuminator can increase the overall detection distance of a night vision device. Before buying one, it is important to check that output power of the external IR exceeds the output power of the external IR (built in.) Otherwise, the external IR would not increase the detection range. Two popular illumination powers are 850nm and 940nm.

Use of an external illuminator can increase the overall detection distance of a night vision device.
Use of an external illuminator can increase the overall detection distance of a night vision device.

Laser vs LED

Two types of illuminating technology currently provide IR output—laser and LED. Given the same output power, laser illuminators can travel further than LED illuminators and thus further increase a night vision device’s viewing distance. Laser illuminators, however, must be diffused in order to be eye-safe so they produce a “grainy” imaging effect when viewed through a night vision device.  Laser IRs also offer a more focused field of view than LED. LED, on the other hand, costs less than laser, but cannot reach the same distance unless equipped with an exceptionally high output power.  Therefore, laser illuminators consume less energy than comparable LED illuminators of the same power.

What is the Difference in IR Wavelengths?

Visible IR 850

The white light source produces a faint red glow, illumination is not visible to the naked eye. Most of the true day/night cameras with removable an IR have a great sensitivity to 850nm wavelength.

Invisible IR 940

The Digisight Ultra N455 has an external 940nm IR illuminator.
The Digisight Ultra N455 has an external 940nm IR illuminator.

This IR does not produce a red glow, making it completely undetectable. Invisible IRs are highly sought after by law enforcement, military and railroad applications where red light is often used. The illumination range is 30–40 percent shorter, compared to 850nm wavelength.

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