How do night vision goggles and cameras actually work?Image intensifier tubes
I can obviously see that if you had an infra reed light you could get >reasonable black and white pictures, but when you are, say flying a chopper >at night like you see those Helicopter emergency fly on the wall shows do, >then you only have the dark and what little light there is from stars and >streetlights, so if they are maybe using low level infra red, surely they >would need the sensors to be super cooled, hardly convenient I'd have >thought!
Brian
I can obviously see that if you had an infra reed light you could get reasonable black and white pictures, but when you are, say flying a chopper at night like you see those Helicopter emergency fly on the wall shows do, then you only have the dark and what little light there is from stars and streetlights, so if they are maybe using low level infra red, surely they would need the sensors to be super cooled, hardly convenient I'd have thought!
Brian
There are a few types, but the ones that don't use an infra red
illuminator use a photosensitive plate that can detect a very small number
of photons per pixel, and amplify that signal to light up a photo emissive surface. For flying, they also use a special filter to avoid the
instrument lighting overloading the sensor.
Early ones used a version of a standard TV camera tube, and a CRT for a display, newer ones have solid state sensors that are sensitive enough to
be able to count single photon strikes on a pixel, and use a computer to multiply that number to drive a digital display as used in top end gaming goggles.
The cheap ones use an IR light and an IR sensitive sensor which drives the output screen. At least one of my camcorders uses an IR filter to block
the naturally occurring IR in daylight conditions, and removes it
physically at night, giving a slightly out of focus IR image of what is
seen, so faces are bright due to being hot, and clothes appear dark, as
they block the IR given off by a body, which works because the sensor is sensitive to IR as well as visible light. It also means that you can use
the camera as a poor man's heat loss detector to work out where your house needs insulating.
On 21/05/2022 10:51, Brian Gaff (Sofa) wrote:
I can obviously see that if you had an infra reed light you could get
reasonable black and white pictures, but when you are, say flying a
chopper
at night like you see those Helicopter emergency fly on the wall shows
do,
then you only have the dark and what little light there is from stars
and
streetlights, so if they are maybe using low level infra red, surely they
would need the sensors to be super cooled, hardly convenient I'd have
thought!
Brian
--
Tciao for Now!
John.
There are a few types, but the ones that don't use an infra red
illuminator use a photosensitive plate that can detect a very small
number of photons per pixel, and amplify that signal to light up a photo emissive surface. For flying, they also use a special filter to avoid
the instrument lighting overloading the sensor.
Early ones used a version of a standard TV camera tube, and a CRT for a display, newer ones have solid state sensors that are sensitive enough
to be able to count single photon strikes on a pixel, and use a computer
to multiply that number to drive a digital display as used in top end
gaming goggles.
I'd have thought though that internal heat might have been a problem which
is why I mentioned cooling it down to a very cold temperature. Even the most >efficient gear gives off heat as it works.
I cannot see the effect of current designs, but I can remember those
pictures of wildlife at night back in the 80s on tv shows where the >brightness was obviously false as it relies upon radiation of heat.
Brian
I think there was a Sony camera with a night vision mode. If used in the daytime, it could see through some clothing. <g>
On 22/05/2022 10:42, Max Demian wrote:
I think there was a Sony camera with a night vision mode. If used in the
daytime, it could see through some clothing. <g>
There was a lot of chatter about that some years ago but seems to have
gone quiet now, either they have made it more difficult to remove or
people have got bored of it.
On 22/05/2022 10:42, Max Demian wrote:
I think there was a Sony camera with a night vision mode. If used in the
daytime, it could see through some clothing. <g>
There was a lot of chatter about that some years ago but seems to have
gone quiet now, either they have made it more difficult to remove or
people have got bored of it.
On Sun, 22 May 2022 at 18:34:16, MB <MB@nospam.net> wrote (my responses usually FOLLOW):
On 22/05/2022 10:42, Max Demian wrote:
I think there was a Sony camera with a night vision mode. If used in the >>> daytime, it could see through some clothing. <g>
There was a lot of chatter about that some years ago but seems to have
gone quiet now, either they have made it more difficult to remove or
people have got bored of it.
Presumably, only clothing that is transparent to the infra-red wavelengths
it saw.
I remember in the 1960s/'70s, there were adverts for "X-ray specs" (or something like that) on the back of some things - comics, I think. I never sent for them. Anyone? I presume they were some sort of fraud - certainly
no electronics were involved.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf
If you're playing a killer monster, be very quiet. -
Anthony Hopkins, RT 2016/10/22-28
Of course you could also get Ultra violet lights. The one I recall was called the big blac light. They tended to be used in discos and the like where certain clothing kind of sparkled as something in the dyes changed
the lights frequency down into the visible ranges.
I guess it was similar to the way Day Glo paint worked that we used to put on the wingtips of model aircraft to help find them in poor daylight.
Brian
I wonder if you could make a camera that worked at microwave or at least millimetric frequencies? Brian
Probably the latter. I don't think you were actually seeing through
clothing, you just saw the effect of other garments insulation in the >brightness of the areas covered.
I wonder if you could make a camera that worked at microwave or at least >millimetric frequencies? Brian
I've seen some such claimed material; it varies considerably, I think in
a few cases yes, seeing through material that was more transparent to infrared than it was to visible light. However, the effect you mention
also contributed - if a garment/material was a lot_more_ opaque to
infrared than to visible, it would stand out more, and thus sometimes
make the uncovered flash seem more prominent.
On 23/05/2022 13:28, J. P. Gilliver (John) wrote:
I've seen some such claimed material; it varies considerably, I think in
a few cases yes, seeing through material that was more transparent to
infrared than it was to visible light. However, the effect you mention
also contributed - if a garment/material was a lot_more_ opaque to
infrared than to visible, it would stand out more, and thus sometimes
make the uncovered flash seem more prominent.
The press and paparazzi use powerful flashguns to get a similar effect
when photographing female celebrities.
I'd suggest doing that sort of thing may well illegal nowadays under sexual harassment law unless there is prior consent.
Brian
On 24/05/2022 08:57, Brian Gaff (Sofa) wrote:
I'd suggest doing that sort of thing may well illegal nowadays under sexual >> harassment law unless there is prior consent.
Brian
Many of the female celebrities probably encourage it because they want
to have their pictures in the media.
On Tue, 24 May 2022 09:02:20 +0100, MB <MB@nospam.net> wrote:
On 24/05/2022 08:57, Brian Gaff (Sofa) wrote:Judging by the pictures they post online of themselves, it seems most
I'd suggest doing that sort of thing may well illegal nowadays under
sexual
harassment law unless there is prior consent.
Brian
Many of the female celebrities probably encourage it because they want
to have their pictures in the media.
of them are pathological exhibitionists who are desperate for people
to look at them. Presumably it goes with the job, or maybe it's more
accurate to say the job goes with that personality type.
Rod.
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