Delft PG1 MS MkII review

Background:

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(special forces prepare for direct action against Iraqi forces.  *photo source: smh.com.au

Flash back to Operation Desert Storm (17 January 1991 – 28 February 1991) in the Persian Gulf region a war waged by coalition forces from 34 nations led by the US against Iraq in response to Iraq’s invasion and annexation of Kuwait. In a night raid, members of the 10th Special Forces group, under the cover of darkness,  scale the wall of an enemy compound and almost immediately come into contact. It was later discovered that unbeknownst to the US troops, the Iraq military had acquired night vison devices from Delft Sensor Systems (DSS) DIEO BV, Netherlands.

Among these Night Vision Devices (NVDs) Supplied to them by DSS was the PG1 MS night vision goggle which were originally developed for use by drivers of Armored Fighting Vehicles (AFVs) and are a second generation night vision system that uses two image intensifier tubes, and features a focus stable objective lens and adjustable eyepieces.

A snap-on infrared light source gives additional illumination for map or document reading. The PG1 MS was in service with a number of NATO and other unspecified armies (mostly European) including the German Bundeswehr and KSK.

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above: PG1 Ms shown with head mount and IR illuminator
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Above, a PG1 MS, typical of the Gulf War era

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(NOTE: The PG1 are equivalent to the PVS5 which is also a dual-tube night-vision goggle used for aviation and ground support. Both units use second-generation image-intensifier tubes and while the US Army still has dozens of PVS-5 on supply they hardly ever see any significant use.)

Night Vision Technology Overview

Night vision technology uses image intensification to allow the user to view details in low light environments by intensifying the existing light spectrum. Low levels of ambient light pass through a photocathode that converts the photons to electrons of light, amplifying them before they are passed through a green phosphor screen where they are converted into visible light.

There are currently 3 generations of night vision technology (Gen1, Gen 2 and Gen 3), each offering more sensitivity and operational capability with less light than the previous gens. I won’t delve into too much detail about the differences between the gens as there is already a sea of information available on the web but I have included a brief summary below for those who may be unfamiliar with the differences.

Passive night vision technology (active NVG use built-in IR illuminators) was first introduced in the 60’s and saw limited use in Vietnam. These early devices featured vacuum sealed, fused fiber optics which provided better center resolution, improved gain, multi-alkali photocathodes and fiber optic input and output windows.

However, gen 1 devices like the AN/PVS-2 Starlight scope, were not only quite bulky but they were unable to provide sufficient light amplification in anything less than full moonlight and ultimately were found to be more of a hindrance to the operator than they were worth.

Generation 2 tubes were developed in the late 1960’s and offer 20,000 times light amplification with the development of the microchannel plate (MCP) which allowed higher electron gains and made observation possible down to about a quarter moonlight. By combining the MCP with the S-25 photocathode Gen 2 tubes were able to produce a much brighter image, increased illumination in low ambient light environments, such as moonless nights, increased light amplification to around 20,000× and a dramatic improvement in image resolution and reliability. Gen 2 tubes have a life expectancy of about 2,500 hours up to about 4,000 hours in higher end tubes.

Generation 2 plus technology provides the user with even more improved performance over standard Generation 2 units by providing increased gain at high and low levels and in some cases provide nearly the same performance as standard Gen 3 tubes.

Generation 3 tubes were first introduced in the mid 1970’s and offer 30k to 50k times light amplification by using intensifiers with increased photon sensitivity due to a gallium arsenide photocathode which is effective into the near-infrared region. In layman terms, Gen 3 devices offer a sharper, and more informative image compared to other generations. The operating life expectancy of Generation 3 tubes are also greatly increased to about 10,000 hours.

Generation III+ devices like the Enhanced Night Vision Goggles (ENVG) feature, an auto- gated power supply system which regulates the photocathode voltage, allowing the device to adapt instantaneously to changing light conditions, a very thin or non-existent ion barrier decreasing the amount of electrons that are usually rejected by the standard Generation III MCP.

Product Review:

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above: PS1 MS MkII mod 0 with ANVIS ball detent mount

This review will focus on the PS1 MS MkII mod 0, this particular unit is equipped with an ANVIS mount but is also available with a WILCOX compatible dovetail mount.

Specifications

  • Weight: 1 kg
  • Dimensions: 120 x 138 x 90 mm
  • Magnification: x0.9
  • Field of view: min 47°
  • Resolution (10-3 lux): 2.5 – 4.0 mrad min
  • Range: typically up to 150 m
  • Type PG 1MS night vision goggles

Image intensifier tube:

  • Type: single stage, fiber input
  • Power supply voltage: 12 kVDC
  • Input Cathode Type: S25
  • Output Anode Screen type: P20 Aluminized

About the PG1/MS MkII (mod 0)

The Pg1/MS MkII is described as “a versatile, passive night vision goggle system designed for armoured vehicle drivers and for medium to short range observation. It is a lightweight, battery –powered and self-contained unit, designed to meet all military specifications.”

The goggle housing is made up of cast aluminum and contains the optics, the image intensifier tubes and the power supply.

The inter-pupillary distance of each eyepiece, can be adjusted independently between 59mm and 71mm. The front lenses are a high speed lens systems with a focal length of 20.5mm, a relative aperture of 1:1 and a T-stop of 1.2, however due to the fact that the focusing rings are coupled, the front lenses do not need to be adjusted separately.

The Image intensifiers are special mono-staged tubes with a thin fiber optic input. The total light gain achieved in each tube is in excess of x750

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above: the MkII attached to a helmet via the ANVIS ball detent mount

The image intensifier tubes are 12kVDC tubes and are equipped a BSP (Bright Source Protection) feature called ABC (automatic brightness control) and DC (Distortion Control). ABC protection circuits automatically control the output brightness of the tube under changing light input conditions. Automatic brightness control (ABC) is designed to protect both the image tube from highlight exposure and the user’s eyes from excessive brightness. This effect can be seen during rapid changes from low-light to high-light conditions when the image gets brighter and then, after a momentary delay, dims to a constant level.

ABC is similar to auto-gating and both serve the same essential function, which is to keep the image intensifier output brightness within optimal limits, protect the image tube and enhance its lifetime. ABC works by automatically reducing voltage to the microchannel while auto-gating turns off the photocathode voltage for brief periods of time.

Performance:

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above, left to right: MkII and an AN/AVS-9

The MkII is a Gen 2 night vision device so it would be a fairer comparison to the AN/PVS5 or another similar MILSPEC gen 2 device. However as most of those reading this  would likely be familiar with the more modern NVDs I thought I would compare it to the AN/AVS-9.

Exelis AN/AVS-9 PS1/MS MkII
Field of view 40deg 47deg
Resolution 57-64 lp/mm 28-45 lp/mm
Objective lens 27mm F/1.23, T/1.35 20.5mm F/1.0, T/1.2
Objective lens focus 41cm to infinity 30cm to infinity
Brightness Gain 5000 fL/fL minimum 750 fL/fL
Battery/Operating time 4x AA/50 1x AA/15
Operating Temp range -32C to +52C -30C to + 50C

(NOTE: 400-450 is about average brightness gain for most Gen 2 night vision devices)

Human Factors

The MkII is just over a half pound heavier than the ANVIS 9 (the equivalent of 3 iphone 5’s) which may not seem like much but when mounted to a helmet can make a considerable difference. While the ANVIS 9 is powered on and off by simply flipping the unit up and down, the MkII unit must be switched on and off manually. The on/off switch on the MkII is located on the right side of the battery compartment, is very simple to operate and is designed in such a way that tactile manipulation is not hindered even while wearing gloves.

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above: the MkII in the stowed position

Utility and Performance

The 47 degree field of view (FOV) of the MkII is very similar to that of the ANVIS (40 degrees) and as there is zero magnification it is an ideal candidate for armored vehicle drivers and for use by foot mobiles.

The unit is water proof and should be able to withstand use in inclement weather, though as with all NVDs, performance  becomes seriously degraded in heavy rain, snow or fog.

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above: the MkII in the ‘down’ position

When mounted to the helmet via the ANVIS mount, it is easily lowered and raised in the same way as the AN/AVS-6/9 (for those of you who are already familiar with that device). I have found that the ANVIS ball detent break-has somewhat of a propensity for getting knocked out of the socket, so it is important to keep this in mind especially when operating inside buildings or where low overhangs are present. As added insurance, I use a WILCOX NVG lanyard to prevent the NVGs from hitting the ground should they get accidentally get knocked off my helmet.

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Above: Wilcox NVG Lanyard for Opscore 3 hole VAS shrouds. The $60 price of the lanyard is small price to pay compared to the cost of having to replace or fix your NVDs

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above images taken on an overcast night

Using NVDs can be a bit like closing one eye which makes accurate interpretation of depth of field very difficult and it is easy to overestimate distance and underestimate depth and height of objects being viewed.

The MkII resolution like most Eorpean-made NVDs is given in mrad (milliradians) vs. the U.S. devices which measure resolution in in lp/mm (line pairs/millimeter). So a bit of math is involved to convert it to a number that is easily compared to more common U.S. devices.

The MkII has a resolution of about 28-45 lp/mm, (keep in mind that measurements is given at a very low level of 10 -3 lux, which is equivalent to  about a starless night). By comparison, the AN/PVS 5 has slightly lower res ratings with a resolution range of 28-38 lp/mm while The gen 3 AN/VIS-9 is much higher res at about 57-64 lp/mm (at 10-5 lux).

The industry gold standard for tube resolution is set at around 64 to 72 lp/mm, however most applications do not require that high of resolution. Some subject matter experts argue that this level of resolution exceeds the capability of the human eye. Many experts recommend a resolution of 45 lp/mm for most operations.

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keep in mind that while the images do a good job of demonstrating some of the device’s capabilities, (an limitations) photographic representations of NVG images are rarely ever completely  accurate and always present a slightly degraded image quality at varying degrees depending on the factors such as camera quality, the steadiness of the photographer’s hand etc. And while these images serve their purpose for this review, it is important to realize that the operator’s view will always be better.

Magnification and FOV

The tunnel vision users experience as a result of NVD use is very drastic regardless of the device used (quite a bit less I am told when using the L3 GPNVG-18s which I sadly, have not yet had an opportunity to try; see photos below). The average human field of view is just over 180 degrees which is drastically cut down to about 45 degrees when using NVDs.  Peripheral vision becomes almost nonexistent with the use of NVDs. It is extremely important that the operator be aware of this and make appropriate adaptations in their training.

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photo source: Tactical Night Vison Company
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Photo source: Tactical Night Vision Company

If you haven’t already, I would recommend that you read the US Military training manual for scanning procedures when using NVDs.

http://www.usaarl.army.mil/techreports/92-10.pdf

While an average human’s vision is 20/20, NVGs can only provide up to a maximum of 20/25 to 20/40, and even this is possible only during optimal light conditions and only when viewing a high-contrast target. With the reduction of either available light or contrast, the user will see an equivalent decline in the overall clarity of the image being viewed.

(the MkII boasts over +750 of light gain which compared to about +400 light gain average for most Gen 2 tubes is really good)

Distortion

All gens prior to gen 3 experience a certain amount of geometric distortion in the image this is minimised however through the use of distortion control that the MkII is equipped with. As an added benefit users with also notice very minimal ‘fish-eye’ effect common to many NVDs.

Weather Resistance

The MkII is built to meet (and in some cases exceed) US MILSPECS for environmental factors and will perform suitably under the most inclement conditions. With dropping temperatures, the risk of internal fogging increases, as I have not had the opportunity to evaluate the mkII’s performance under severer cold conditions my feedback in this regard is limited. I did run the system extensively during a particularly cold winter evening (+2F) and did not note any fogging or degradation in performance. The MkII is equipped with replaceable Silica-gel desiccator cartridges which is designed to further protect the device from moisture.

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above: several sealed desiccator cartridges in their original packaging
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The desiccator cartridges are a screw cap design that are easily switched out with nothing more than a coin.
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replace the desiccator cartridges when they go from white to a pale, pinkish color.
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English translation: Each desiccator cartridge is contained in a sealed poly package. The visual indicator should be light blue in color when the moisture absorbent is dry and active. The blue color indicates an 8% relative moisture level.  Do not use if the poly package is damaged or if the indicator is a pale pink color.

I have yet to test the ‘floatability’ of this device.

Overall Cost of Ownership

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above: device test sheet  with user’s manual

Gen 2 tubes have a life expectancy of about 2,500 hours up to a maximum of about 4,000 hours and I imagine that the MkII tubes will likely need to be replaced within those timelines as well. Finding compatible replacement tubes shouldn’t be too difficult as a quick web search should bring up more than a handful of results (mostly European). There is a visual indicator on the sides which tell you when the silica-gel desiccator cartridge needs to be replaced. When these turn a pale pink color they should be replaced.

The MkII uses a single AA battery which are easily acquired and are relatively inexpensive.

All image intensifiers will “wear out” over time due to gases generated within the tube that migrate to the photocathode and slowly kill it. As mentioned earlier, the MkII has a BSP (Bright Source Protection) circuit built into the device. This circuit automatically reduces voltage to the microchannel plate when the system is exposed to bright light sources which protects the image tube and enhances its life

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above, left to right: AN/PVS15, MkII, AN/AVS-9

Above, is side-by-side photo comparison between the PG1/MS MkII, and two commonly used NVDs; ANVIS 6 (Aviation Night Vision System) and an L-3 AN/PVS 15 both still currently in service with US Special Operations.

These photos are meant to demonstrate the physical size of the PG1/MS MkII relative to currently issued operational kit.

PG1/MS: 4.72” (L) x 5.43”(W) x 3.54” (H); Weight: 35.27 oz.

AN/PVS15: 4.25″(L) x 4.5″(W) x 3.0″(H); Weight: 22.9 oz.

ANVIS 6: 4.75″(L) x 4.5″(W) x 3.25″(H); Weight: 29.9 oz.

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above, left to right: PVS15, MkII, ANVIS-9

Conclusion and insights:

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above: AN/AVS-9

Night vision technology as revolutionary as it is, brings with it, its own unique downsides which an operator must train for. NVDs, regardless of what gen, will (at varying degrees) affect the users’ depth perception, and peripheral vision. Visual clarity rapidly diminishes for objects over 400ft, even more so if the object is fast moving. Weather related challenges such as rain, clouds, mist, dust, smoke, and fog all affect performance as well. It is also important to keep in mind that night vison tech does NOT work in zero light environments and the use of additional IR illumination may be required in these situations. Keep in mind that this also creates an added risk to the operator when engaging an enemy who may also be using similar technology.

As with any other tool, it is important that each operator trains with the chosen device and if possible, try to simulate the situational environs of their intended use to gain familiarity with its functions, capabilities and limitations. From a tactical standpoint, the ability to quickly discriminate targets and non-combatants within the highest level or probable accuracy in extremely paramount. The quality of the NVD could mean the difference between something appearing to be a guy holding a gun to a guy holding a TV remote. Devices with objective lenses that have insufficient magnifying power and a weak image intensifier will also have a tendency to give more of a tunnel vison effect when viewing the surroundings through the tube, isolating the user and dramatically reducing situational awareness.

Military or LEO professionals who work for a department backed by the big green machine, should have no reason to settle for anything less than the very best and with the advances in Night Vision technology there is a lot to choose from.

However, if you are a non-US resident with no access to ITAR controlled devices, a recreational shooter, hunter, a hobbyist or someone who wants some of the “big boy benefits” of a goggle-style NVD without having to spend $5k – $10k and up on a pair of ANVIS 6/9s, PVS15, or dual mounted PVS 14’s, then it may be worth looking into the PG1 MS MkII.

(NOTE: US Made Gen 3 NVGs are regulated by ITAR and are not allowed to be exported outside of the country)

Based on the information I was able to find, Delft Sensor Systems Netherlands B.V. listed the operational status of PG1 MS MkII’s as “in production” at the time that they were aquired by Photonis USA in around 2006.

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Manufacturer’s info:
Delft Sensor Systems Dieo Bv,

Rontgenweg 1, 2624 BD Delft
Zoekresultaten:
Delft Sensor Systems Dieo Bv
Rontgenweg 1
2624 BD Delft

Zuid-Holland

Netherlands

Tel: 015-269 8050

PHOTONIS Netherlands B.V.
Dwazziewegen 2, 9301 ZR Roden
P.O. Box 60, 9300 AB Roden
The Netherlands

T +31 50 501 8808
F +31 50 501 1456

PHOTONIS USA Pennsylvania, Inc.
1000 New Holland Avenue
Lancaster – PA 17601-5688 – USA

T +1 800 366 2875 (Free in US & Canada)
T +1 717 295 6000
F +1 717 295 6096

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