Simrad GN-1

The GN-1 is a series of biocular night vision devices made by Norwegian SIMRAD, known for its lightweight yet rugged housing.

It is powered by two standard AA batteries and has an onboard IR LED illuminator. It comes with its own set of accessories from factory among which are a headworn mounting harness, carry case and a retention string to be worn around ones neck to prevent the device from falling and being damaged.

The GN-1s lightweight and low profile construction, unique looks and ability to hold its own among current housings and devices has earned it a strong cult following and remains in high demand among collectors and enthusiasts both in Europe and globally.

Design and features

The form factor allows the GN-1 to be a very low profile device since its construction has placed the IIT and the devices various mirrors and prisms so that they transmit light sideways relative to the users face.

A notable feature of this particular design is its large objective which is placed left-of-centerline as well as above the users line of sight when operated with its proprietary head mounting harness (jokingly nicknamed ”the chin remover” among enthusiasts). This design gives the device a slightly left-biased field of view which may take some getting accustomed to for users familiar with biocular devices such as the PVS-7 that are constructed with centerline mounted objectives at eye-height.

The GN-1 eyepieces are adjustable and rather small compared to eyeboxes of other systems and standards, making the maximum functional distance between user eye and ocular significantly shorter than many other devices.

Optical construction

As mentioned the GN-1 objective is distinctively large and behind it a circular mirror is placed at an angle so as to reflect the incoming light into the lenses of the light tunnel.

From there an adjusted image is projected onto the IIT photocathode, whose display in turn is funneled into a series of 45-degree mirrors housed inside a tunnel in an L shape where it finally enters the dividing prism and the phosphorous display image is thus projected into the two eyepieces.

This array of lenses, prisims and mirrors was designed specifically for use with IIT using green phosphorous displays. If a white phosphorous display equipped IIT is installed into a GN-1 device a peculiar optical effect arises: the blue wavelenghts are refracted improperly and so causing a subtle yet visible effect of an offset ”ghost” image in the eyepieces.

Variants

Among its variants is the GN-1C, designed to be used while driving a vehicle. Its primary distingushing feature is its objective being coated with a visible spectrum light filter to lessen interference and haloing from dashboard and control panel lights. A drawback of this is that less stray environmental and background light from the NIR-spectrum (Near Infra-Red) reaches the photocathode, making its performance in extreme low light conditions somewhat less bright than a GN-1 unit without this particular filter coating.

Since the GN-1 was released prior to current standard attachment shoes there are various adapters available for mounting the GN-1 to contemporary systems of head-carry. Some adapters for helmet carry require the GN-1 to be rotated upside down sine the functional eye relief is not always compatible with helmets while in its originally intended position. This has the added advantage of shifting the units input to right hand offset and below sightline height, which is especially beneficial for right handed operators of small arms.

The GN-1s lightweight and low profile construction, unique looks and ability to hold its own among current housings and devices has earned it a strong cult following and remains in high demand among collectors and enthusiasts both in Europe and globally.

Confirmed Users

This list is incomplete, feel free to add confirmed entities and organizations employing the device.

Military

Swedish Armed Forces

The GN-1 series has been employed by Svenska Försvarsmakten and is (as of August 2022) still the standard issued night vision device for service personnel.