Thermal Imaging Cameras

Three important reasons:

1) Limited demand compared to visible light cameras

2) Detectors are expensive

3) Lenses are expensive
There is a world of difference between the near infrared that your typical filter supplies, and the far infrared that thermal imagers record.

I think you first answer says most of it. Also, you're correct about imaging thermal IR. However, there are some weird and interesting thing you can play with...

Several years (a lot) ago, we made digital cameras by grinding off the tops of memory chips, then putting them in a case with a lens. Taking pictures was just a matter of scanning the memory array and assigning them to pixels on the PC monitor. Anyway, we found out very early that they were more sensitive to thermal IR than any other part of the spectrum. For example, a warm iron made a great spotlight.

Can you provide me with the data on how you did this?

Do you think that an older camera could be modified to perform this, (thermal imaging)?

I do not need anything of manufacturing/military grade, I just want to take photos/videos of home to see/show leakage (hot/cold spots).

mudhawaii

Basically, we had these small, round aluminum housings, which we fitted with a lens that could be used to focus an image.

We then ground the tops of the memory ICs down until the little, round opening above the memory chip inside appeared. The memory chip was fitted into the aluminum housing so that the lens focused on it. I think we had a little circuit that would scan the memory array and send the values to the PC through the serial port. From there, our software just read the bits and assigned their value to various pixels on the monitor screen. I assume these days the resolution of the image would be much higher because of the current density of memory chips.

Another thing that might work for you is to check out eBay. They always have lots of good used scientific gear for sale. I go there to pick up laser parts all the time. They usually have photomultiplier tubes and IR imaging systems.

You will find that low IR is a light while thermal is actually a radiation. thermal is closer to the x-ray bands.

To photograph low IR you'll need a 87, 88, or 89 filter for IR. The only problem with them is they will block out almost all visible light. I recommend a cover with a magnifier for your screen. Note: there are lots of hint/how-to-do's if you type in "infrared photography" or "infrared cameras".

mudhawaii

"You will find that low IR is a light while thermal is actually a radiation. thermal is closer to the x-ray bands."

This statement does NOT make sense. Light and x-rays ARE radiations. Thermal radiation is BELOW visible light in frequency (longer wavelength). That's why its called Infra-Red (Infra is Latin for below) Ultra-Violet similarly is radiation having a higher frequency (shorter wavelength) than visible light, and x-rays are considerably ABOVE those.

I go with you on your comments completely.....

The statement is in regard to photographic definitions, not mine. You are correct all light is radiation and all radiation is light and thermal energy is radiation/light (in some form).

I believe they make the break at the point of when specialized equipment/film is required to capture the images. For example normal B&W and color film will capture near IR and UV with only filter(s) attachments. Specialized films for these are available to get more enhanced images also. While, the remainder of the spectrums require more advanced films, filters, cameras, development and printing proceedures.

I hadn't even thought of film! I suppose there must be a few people still using it... What about the kind of glass or other substance required for lenses to be transparent to low energy IR?

Yes, I must be old hat. I still use film for some items. Even though I have a 7.1 MP digital I still find film works best in some applications (especially when you do long exposures or want to push and obtain the grain effect).

Anyway here is a few links to give you more information on IR with film or digital.

www.mat.uc.pt/~rps/photos/FAQ_IR.html

www.wrotniak.net/photo/infrared

Good luck if you decide to try some of this.

There's one important part to the type of IR imaging that you seem to want to play with, and that is spectrum stability.

Years ago, I was playing with Kodak IR film and filters. How I was disappointed when the picture I took of my friend's car engine turned out to be just that... A picture of my friend's car engine. I was expecting to see all sorts of detail showing hot-spots and cooler areas, and that's exactly what I didn't get.

When you use the type of thermal imager that can show 98.6° skin against a 65° wall, things get really expensive. I presume the reason for this is these types of imagers have to be extremely accurate, discriminating frequency and isolating from noise. If you think about light at higher frequencies, even with lasers you can often get spectral noise that shifts the light around a 100nm center frequency.

At the thermal end of the spectrum noise is much harder to deal with. I'm assuming there is not much frequency difference between, say, 100° and 80°. So stability is paramount. Unfortunately, stability costs bucks!!! I'm guessing that these imagers use either TEC coolers or may even need liquid gas refrigeration to eliminate noise and stabilize the very narrow spectrum you are trying to capture.

Does this make sense?

Yes it does make sense at least to me, thanks.

An electronics company that I order stuff from has produced a small (cheap) thermal sniffer, that helps to find cold spots in a house where insulation is not as it should be or there is a draft from outside.....it does not use images per se, but is still interesting I feel....

Sadly its only in the German language, but there is a picture of the device and it would appear to work in a very simple manner in that you give it a reference temperature and it shows you where the temperatures are the same, or higher or lower with a colored LED and a sound output....I must buy one soon!!

It is a complete kit of parts with all parts and a pre-printed and drilled case....click here for the link:-

Pyro Pointer

Interesting Andy! I hadn't seen anything in kit form recently...

I only know a very few words of German. Do I understand correctly?

Messbereich: -10 °C bis 300 °C (sensing temperature range)
D:S-Verhältnis: 6:1 (Signal-to noise ratio)
Umgebungstemperatur: 0 °C bis 40 °C (center temperature range)

I assume the price is in Euros...

On the other hand I have an infrared thermometer (tpi 371) that indicates temperature to 0.1° F or C, with a laser pointer to indicate what object is being observed. I bought it 2 or 3 years ago. If I recall correctly, I paid around 125$US. I just looked and DigiKey has them for 120$US. Here's a Link.

One thing I have found very interesting is to point it at the sky - really shows what clouds do!

Dick

D:S Verhältnis, is to do with the distance from the object to be assessed, if the object is say 10CM across, you need to be 60CM away to measure it correctly. Its to do with the width of the measuring window.....

Of course! Distance to Spot ratio, just as shown on the specs for the Fluke.

Dahnke!

I didn't mention that I lent my tpi 371 to a friend, and while he had it, the display went funky. I haven't tried very hard to see if I could repair it.

Just after I sent my last post, I checked an email from Fluke. They have a closeout on this:

It is on closeout for 104$US, and has a max-min feature mine does not have. Fluke also advertises it withstands a 1-meter drop (Which I suspect mine didn't).

I'm going to order one... I doubt if the closeout will be available outside the US, but here is the link, just in case.

Dick

the sensor is expensive and it can be use for militry.

this is very important. and it has less pople use it. if it has large yield, it will cheaper as handcam.

Ok, limited application will raise the price but starting at $3000.00 and going up is too high. As for military and police applications they use the same units that are available to the civilian market in the $12,000 and up price range.

I am really just looking for something that will get me into the thermal range with out an arm and both legs. More of a fun/hobby type of realm.

mudhawaii

Being in our volunteer fire dept, we use our Thermal Cameras all the time. One thing that brings some casual grins is the fact that if you pass it past a woman who has had some cosmetic enhancements to her upper body, they show up on the camera. Just a thought to help give you more incentive to upgrade.

During the Viet Nam war, I spent a lot of time in the Far East, quite a lot of time with US forces (no I did not help to Bomb Hanoi!!) and there was a photograph of a young actress with red / blond hair (Anne Margret), taken while she was on stage with a thermal camera.....it looked as though she had forgotten her underwear......!!!

Which she hadn't in fact, but the thermal camera just ignored them and took a thermal photo of her.....

Somehow it got copied and passed around the US Fleet!

Pretty lady......no I did not manage to get a copy, sadly......

I wonder how many $$$$ a thermal camera would cost in 1967??? Military use only.....!!!