question Infra-red night Vision

[Rangie]

Many of us with ex-mil landrovers, not to mention FV's, have the optional infra-red circuit fitted to out vehicles.

I see the headlamp covers pop up on fleabay occasionally, but what else is involved in the use of the system?

Do you use powered goggles/image intensifiers to view the terrain or just wear extra spectacles?

How much visible light is produced from the filters?

Is the rest of the kit mega-expensive? :cool2:

 

I haven't seen/read much about it........

 

Alec.

[private mw]

good question i wondered the same :???

[sirhc]

Most armoured vehicles can be fitted with a image intensifier periscope for the driver. With the lamp covers fitted, when using the sight the headlamps work in much the same way as they do normally - but in infra red. I've used the one in my Sabre a few times and it's quite impressive. You can get image intensifier goggles which do the same thing.

 

Chris

[fv1609]

I haven't seen/read much about it........Alec.

 

Some stuff about IR development in these:

 

http://www.hmvf.co.uk/pdf/Tabby01.pdf

 

http://www.hmvf.co.uk/pdf/Tabby02.pdf

 

http://www.hmvf.co.uk/pdf/Tabby03.pdf

 

http://www.hmvf.co.uk/pdf/Tabby04.pdf

[Rangie]

By gum, the Sage of the HMVF has spoken. :cool2:

Absolutely excellent Clive, thats my bedside reading taken care of this evening!

 

Brace yourself for the inevitable questions....... :-D

 

Alec.

[AlienFTM]

By gum, the Sage of the HMVF has spoken. :cool2:

Absolutely excellent Clive, thats my bedside reading taken care of this evening!

 

Brace yourself for the inevitable questions....... :-D

 

Alec.

 

I assume Clive' s links tell you this. Active Infra-red (wherein infra-red light is beamed - either from dedicated IR sights, see early CVR(T)s, or filtered from white lights) was an early generation of night vision.

 

Having cast the landscape with IR light, it became visible via IR optics.

 

Unfortunately, being an active system, anybody with the right optics would see the IR light and once "the other side" had them, you might as well use white light and shout, "OVER HERE!"

 

Obsolete by the mid-70s and I cannot remember whether Scorpion had IR light by 1976. They were certainly gone by 1978.

 

Image intensification became the norm and that's what drove the Scorpion night sight.

 

Thermal imaging works in the far infra-red spectrum (as opposed to near infra-red used above) but it's entirely passive, undetectable and different from active IR.

[ruxy]

Fine BUT - these things , filters

 

 

Market Economy , ePay etc. - they have been creeping upwards in a never ending £ spiral..

 

They seem to be desired by everybody with a pair of FV.700's

 

Now - all the MOD trucks built up to late 1970's with a IR inhibited switch , one would assume there was a ready available supply of filters available.

 

So - what I don't understand is this , where did they all go , smashed ?? If they had been released at disposals then they would be at a realistic price now.

 

Or - is there a few Nissen huts somewhere stacked floor to corrugated roof with tens of thousands of pairs of filters, and if so - why ????

[Rangie]

So, using these on headlamps it becomes an active-IR source, filtering out the white light.

 

I should only then require a set of IR goggles/optics to view the reflected IR light, correct?

 

However, is there still the requirement for an image intensifier, or does it depend on the strength of the headlamps/IR source??

 

I don't suppose anyone has a picture of the kit required....................

 

Alec.

[fv1609]

So, using these on headlamps it becomes an active-IR source, filtering out the white light.

Yes

 

 

I should only then require a set of IR goggles/optics to view the reflected IR light, correct?

Yes

 

 

However, is there still the requirement for an image intensifier, or does it depend on the strength of the headlamps/IR source??

Not sure what you mean. But an image intensifier will also detect actively IR illuminated objects & sources.

 

 

I don't suppose anyone has a picture of the kit required.

There are some in the 3rd or 4th article, can't remember which.

 

 

 

Use of active IR sources is no means outmoded. This set up is on my Wolf very recently on active service.

 

 

[Rangie]

Excellent Clive, i reckon I'm nearly good to go for an experiment now!!

 

Got the headlamp filters home now (although how much of a light source 36W pre-focused lamps are, shall prove to be interesting....)

 

Referring to the Tabby systems, an image intensifier and focussing eyepiece is still required in the goggles to amplify the reflected IR Beam.

 

I'll have to get creative with an intensifier tube etc now. Here was me half-thinking a set of filters in a pair of welding goggles would do the trick!!.............

 

Hmm,

Alec.

Edited February 7, 2011 by Rangie
Re-think

[fv1609]

Alec, if you put the filters over the headlights obviously to the naked eye you will see nothing. If you put you hand there you will feel warmth.

 

The domed IR filters were an improvement to the earlier type that were flat, but had an identical fixing arrangement.

 

Up very close you will see a slight glow of the filament through the filter, particularly on the earlier type. After all it is just red glass & in fact for the first half of the war the code word Tabby had not been coined, the term was RG Equipment ie Red Glass equipment. That was not entirely secure, nor indeed was Tabby as the Germans coined most of their systems after animals that had good night vision. I would have thought it better to have called the systems something wholly unconnected with night vision like "boiled egg" or something to confuse the Germans & 5th columnists.

 

In a Tabby viewer there is no amplification just an image converter tube with a cathode screen at 3,000 volts. Obvious there are lenses to focus the incoming IR in the same way as one would focus 'light' except that there are IR filters to restrict its bandwidth & limit damage to the screen from strong light sources (although these would have an IR content still)

 

No tuning necessary the filters are very broadband.

 

Your 36w bulb would give some useful coverage. I have a Russian hand-held monocular that has in effect a built in torch + IR filter. It is pressed to help illuminate dark spots that are shielded from ambient residual sources eg moonlight. Although moonlight is only reflected sunlight!

[montie]

Alec, if you put the filters over the headlights obviously to the naked eye you will see nothing. If you put you hand there you will feel warmth.

 

The domed IR filters were an improvement to the earlier type that were flat, but had an identical fixing arrangement.

 

Up very close you will see a slight glow of the filament through the filter, particularly on the earlier type. After all it is just red glass & in fact for the first half of the war the code word Tabby had not been coined, the term was RG Equipment ie Red Glass equipment. That was not entirely secure, nor indeed was Tabby as the Germans coined most of their systems after animals that had good night vision. I would have thought it better to have called the systems something wholly unconnected with night vision like "boiled egg" or something to confuse the Germans & 5th columnists.

 

In a Tabby viewer there is no amplification just an image converter tube with a cathode screen at 3,000 volts. Obvious there are lenses to focus the incoming IR in the same way as one would focus 'light' except that there are IR filters to restrict its bandwidth & limit damage to the screen from strong light sources (although these would have an IR content still)

 

No tuning necessary the filters are very broadband.

 

Your 36w bulb would give some useful coverage. I have a Russian hand-held monocular that has in effect a built in torch + IR filter. It is pressed to help illuminate dark spots that are shielded from ambient residual sources eg moonlight. Although moonlight is only reflected sunlight!

 

It hit me like a hammer, could this be the same???

post 224 Saracen build-up

Edited February 8, 2011 by montie

[Timinder]

I guess the panel section with the "IR" in a star shape is to turn on IR lighting, and the "IR" selections on the rotary switch are for IR light operation (I think the curved shape like a bent "T" could be a "brake" icon)?

[AlienFTM]

is there still the requirement for an image intensifier, or does it depend on the strength of the headlamps/IR source??

 

No. An image intensifier receives all ambient light and passes it through a series of cascades (hence the length of the Scorpion night sight) amplifying what light it gets. It will achieve nothing on a cloudy, moonless night where there is no ambient light. But II is an entirely-self-contained passive system (nothing transmitted).

 

Active IR lights up the target with IR light which is detectable through IR Goggles. But because it is an active system, anyone with gogles can see it.

 

If you have an II sight and bad weather conditions (see above) it is easily enhanced by lobbing a flare (I remember doing night shoots on cloudless nights and those times when we had a 432 mortar behind the firing point lobbing starshells in the sky, the II sight was like day - even if everything was green. The white light flare also gave off a lot of IR light.

 

But again, the light lit up everything and it was a two-way street, and the enemy would know somebody was looking at them even if they couldn't see them. So it was far preferred to use passive II.

 

Trouble is as I recall the II sight was monocular rather than binocular, so that depth perception was impossible. I remember engaging a target at 400m only to discover it was about 50m away. It didn't half go bang, even with a PRAC round. clods of earth coming back at us kind of shook the driver and commander who were both blind without a night sight.

[Stableboy]

have had and used Tabby, and done some research about it;

be very aware of the high voltage involved if you play with this old kit and perished wiring!

 

have seen ww2 images showing IR headlamp filters fitted to Sherman and Jeep of 79th Armoured Div, heath robinson style mount of viewing goggles (like binoculars) made from something like meccano to place the viewers near-ish to the drivers head; in the case of vehicle mounting, there is a large transformer which bolts to the vehicle with ws19 style rubber mounted feet, and a seperate control box to be fitted where convenient.

There was also a single tube viewer, like one half of the driving Tabby viewer, to be used mounted on the Sten Mk2S, the one with the sound moderator (not silencer - it doesn't!), with some sort of powersource in a large backpack..

 

Landrover use would originally have been headlamp filters in conjunction with CUB head mounted vewers - CUB = 'Common User Binocular' - so all crew could see, but as pointed out, in active IR 'i'm here, shoot me' status!

 

quality / convenience does not compare with the Litton NVG headset that a former spanish speaker conveniently left for me; they even have a dinky little light source of their own so that in an enclosed space ie, without starlight, you can see fine (albeit in green!).

[ArtistsRifles]

Sounds the same as the system mounted on the OT then... The commanders periscope works in either mode whilst the driver gets a special headset with a pair of powered "bino's" on it. Feels bl**dy heavy in the hand but surprisingly comfy when worn. Binos fold up for normal use. IR lights were the (in UK tems) offside headlamp and the turret mounted lamp. Not sure what light spectrum/frequency the big light in front of the Commanders position works in......