Economy thermal imager?

[notme]

Might as well buy the real IR imagers that the security camera folks
are pushing now, if you are going to do that.

I think they sell them by the box at Frys'.

When i search Frys.com for "infrared" I get all kinds of IR communication
devices (headphones, etc.), an intrusion-sensor security system, and one
security camera that uses IR illumination.

Is this what you mean? ::

<http://www.frys.com/product/5382748?site=sr:SEARCH:MAIN_RSLT_PG>

Thanks.

 

[Archimedes' Lever]

At the same time, Fischer Price sold a B&W "toy" camera for $150 that
could have a Ge or Pyrex lens or filter put on it, and it would do IR
very nicely.

Perfect proof that most in the group are idiots.

Not one comment on this well known anomaly as the years ticked by.

Now, the idiots are even talking about a reduced range setup.

This toy was around in 1987. I am sure many can be found in the used
channels.

http://cgi.ebay.com/Two-Fisher-Pric...in_0?hash=item4cea793c53&_trksid=p3286.c0.m14

 

[OutsideObserver]

That relates to what Don Klipstein said, and I've been thinking about that..
it's ame for me if the source is low intensity, broadband, and at edges of
IR. Orangish greyish brownish.. But what if the source is narrowband, much
deeper into IR, and fairly strong? To me such sources (unlensed 5 mW laser
diodes, etc) look maroon, a distinct red that is so deep and dark it is to
red as deep violet is to blue. And both ends of the spectrum seem to reach
toward each other like the closing of a circle. Anyone else see it this way?

NB red is constructed by the

Where can I get one? This needs trying. What form is the neodymium in,
obviously not metal sheet... Doped glass?

You guys should talk to this guy. He knows exactly what he is doing.

His name is waterhed

http://cgi.ebay.com/Modified-Pxl-20...in_0?hash=item1c0bcee13b&_trksid=p3286.c0.m14

 

[Martin Brown]

Years ago, I collected a set of LEDs with various wavelengths.
One was 700 nm. It was a very pleasant (to my eye) deep red.

The nominal peak wavelength of an LED is +/- 20nm so there would be some
visible deep red component in the wings unless you also had a long
pass filter. A lot of IR LEDs have a black organic dye in them to mask
any trace of visible red emission. 750nm & 820nm ones look pretty well
black to me.

Regards,
Martin Brown

 

[Fester Bestertester]

At the same time, Fisher Price sold a B&W "toy" camera for $150 that
Where would one find such a lens to replace the standard lens?

Thanks.

 

[Archimedes' Lever]

Where would one find such a lens to replace the standard lens?

Thanks.

Did you think to try Edmund Scientific or some optical lens coating
supplier?

http://www.edmundoptics.com/onlinecatalog/search/index.cfm

 

[Archimedes' Lever]

The FP uses a CCD so can't work as a thermal imager. Near IR, maybe,
but that isn't germanium lens territory.

"Can't work"? You're an idiot. The first IR imagers were CCD. They
came out before CMOS image planes were even around.

As for the lenses, they are specifically for narrowing a spectral
response.

http://www.thorlabs.com/images/TabImages/GermaniumTrans.jpg

OK. So you found a site that gave you a good picture of what passes
through Germanium. So what?

Most digital cameras work nicely in the near IR.

So what? The FP device did as well. All that was needed was a bit of
gain increase after placing the filter.

 

[Martin Brown]

"Can't work"? You're an idiot. The first IR imagers were CCD. They
came out before CMOS image planes were even around.

I'm with John on this one. The first CCDs were largely in the visible
with a strong peak sensitivity in the *near* IR and with a very big push
to get them out to much longer wavelengths on somewhat exotic materials.
I knew an astronomy imaging group that were given new military chips to
test because they could turn one into a fully working prototype camera
way faster and cheaper than the approved contractors.

Rough graphs of the typical sensitivity for silcon CCDs with front and
back thinned window construction are online at:

http://www.andor.com/learn/digital_cameras/?docid=315

Their response does not extend much beyond 1000nm which is still an
order of magnitude short of the roughly ~10um IR wavelengths needed for
thermal imaging at ambient temperatures.

Eventually they did get longer wavelength CCDs working, and they stopped
at a particular point. As the man said "what we have is good enough to
see what *we* need to see". Astronomers were a bit disappointed that
after that they had to pay for their own chip R&D. It didn't stop
terahertz sensors eventually being made though. Strangely the terahertz
image of my favourite object Cass A appears to have been removed from
the web.

As for the lenses, they are specifically for narrowing a spectral
response.



OK. So you found a site that gave you a good picture of what passes
through Germanium. So what?


So what? The FP device did as well. All that was needed was a bit of
gain increase after placing the filter.

That only gets you near infra red. The thermal band for things in the
temperature range 0-100C is much more tricky and generally involves
exotic doped materials, germanium lenses and cunning optical design
since the emissions from the casing start to be almost as bright as the
target. Some form of multistage thermoelectric cooling is usually
employed or LN2.

Regards,
Martin Brown

 

[Archimedes' Lever]

Their response does not extend much beyond 1000nm which is still an
order of magnitude short of the roughly ~10um IR wavelengths needed for
thermal imaging at ambient temperatures.

Our first imagers came out in '86, and they were LN2 cooled 16 color, 4
frame per second devices that sold for $95k each.

If the imaging plane on them was something other than CCD, I was
unaware. I suppose it could have been a micro-array of bolometers.

 

[Paul Keinanen]

The FP uses a CCD so can't work as a thermal imager. Near IR, maybe,
but that isn't germanium lens territory.

If you look at the black body spectrum, the power density drops quite
quickly at wavelengths below the black body peak wavelength. The cheap
IR sensors measure the amplitude around 1-2 um and if you have a idea
of the spectral distribution in that area, you should be able to
(gu)estimate where the spectral peak is and from the Wien law what the
temperature is.

Paul

 

[Martin Brown]

CCD detector + germanium lens = zero response.

You need to specify *silicon* CCD + germanium lens = zero response.

QWIP arrays work from 1um down to around 12um from the open literature.
Even has a Wiki entry.

http://en.wikipedia.org/wiki/QWIP

Earlier systems were more like bolometers using doped germanium or PbS.
Infrared "the new astronomy" was hot in 1975 and got hotter as the
sensors became ever more sensitive and better resolution.

Regards,
Martin Brown

 

[Archimedes' Lever]

CCD detector + germanium lens = zero response.

John

You + logic = water + oil.

 

[Archimedes' Lever]

No idea what was in the thing I first saw, but it was a lot earlier than
1986, more like 1978 or so. I was a young kid, taken to the Science Museum in
London. The imaging wasn't great, just contoured moving blobsfo false colour,
but shapes were well defined, the refresh rate better than most simple
webcams. It could see an electric iron, and it could see me vaguely, and my
hand fairly well when I waved it open-palmed in front of the camera. I don't
remember the camera being especially bulky. It was definitely picking up
emissions, this wasn't reflection of near IR light. Maybe the mechanism was
described, but at that age I wouldn't know.

This one could see the remnant of heat your hand would leave on an
ambient formica desktop after ten seconds. It could still see the
differentials nearly a half hour later. It had a 0.1°C sensitivity.

 

[Archimedes' Lever]

So do you think that a germanium lens would make the FP toy into a
thermal imager?

Yes or no?

John

A window does not "make" anything into anything. Windows are used for
filtration, just like say a "bandpass filter".

The camera has optics already. All it would need is a windows of the
appropriate spectral range for the desired intended use.

 

[Archimedes' Lever]

I'll take that for a weasel-out-of-the-question.

John

Look, you retarded ****! One does not "make" a goddamned IR imager from
the fucking lens.

When your mentality rises above that of stupid twit, perhaps you will
learn how to word your questions more appropriately.

Until then, it is YOUR fucking problem, dipshit.

 

[Archimedes' Lever]

Neither does one get thermal images by putting any kind of filter or
lens in front of a Fisher-Price toy CCD camera.

There's a reason that thermal imagers cost $10K.

John

Except that in your case, Johnny, your noise floor is so high that any
"information" you attempt to convey is muted by the blatant "My name is
John, and I am retarded" baseline siren.

There is a reason you don't know what is going on.