With ever increasing fuel costs, I'm wondering whether a thermal imaging camera would be a useful thing to have in order to detect parts of the house which would benefit from more insulation.
Many of these are silly money for occasional use - many hundreds if not thousands of £. However, there are also devices for £200 or so which plug into smart phones and (allegedly) convert them into thermal imaging cameras. Here is one example:
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are also USB-C and lightning versions.
Does anyone have any experience of these? How useful are they likely to be? Does the resolution of only 206 x 156 mean that they're a complete waste of time?
I've only used the FLIR ones - the sensors are good but build quality of the unit is bad and they have an annoying habit of dying if you haven't used them for a while. The software is also crippled: they used to have timelapse and they took the feature away in an update. Some of them are artificially capped as to their maximum temperature. They're also limited to 9 Hz refresh rate for US export control reasons (otherwise would be a gift to guided missile builders everywhere).
I had one that died (complete brick, even once I'd externally recharged the battery) and I harvested the sensor and put it in this:
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turns it into a USB webcam which is more useful than the annoying phone app. I have hacked the Purethermal Python software a little to display spot temperatures for min/max/centre.
The base Flir sensor is the 80x60 Lepton2, the better sensor is the 160x120 Lepton3 (annoyingly the Flir One Gen2 was 160x120 and they downgraded to
80x60 in the Gen3). The 2.5 and 3.5 versions have radiometry, ie each pixel records the accurate temperature, while the 2.0 and 3.0 versions only record spot temperatures for the frame and the rest is approximate.
The Flir phone cameras have a second optical lens and the software combines the images to 'improve' the resolution: means you can pick out details, but can be misleading because they aren't actually there thermally. That's why the images look sharper than the really are.
This is a screengrab from my tweaked version of the Purethermal software, with only a 160x120 Lepton3 sensor and some fudged radiometry temperatures (Lepton 3.0 does not offer radiometry officially and so this is uncalibrated):
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As you can see the resolution is enough to make out the radiator pipes and the cold spots, which is what you want it for. Since there is no visible light sensor, the image is not having non-thermal 'detail' postprocessed onto it.
There are some Chinese ones that are 8x8 or 32x24 and I don't really rate those as usable, although perhaps in a niche application. Aliexpress has a few that are 120x90 and 256x192 which are better, although I'd beware in case that's fudged with an optical sensor. They're roughly similar pricing to the Seek.
Not used the Seek one but it looks like they're not using a Flir sensor, and the raw resolution looks good. A lot depends on the software and how crippled it is (or not). Seems competitive for the price anyway.
I have a Seek Thermal self-contained TIC. IIRC it's the same resolution as above. It's a few years old but it's proved invaluable in my line of work. IME they make good quality kit.
Fun parts - look at the handprint image when your hand has been removed. See where your central heating pipes run by looking at the floor temperature. Look at those wall-warts!
I see they do a camera for £470 inc. VAT. It's up to the individual to decide whether that's worth it or not, But if it's really good quality kit, then it might be good value for the average punter.
My next birthday present to myself? There's not much insulating to be done to a 400-year-old house, but even so, there are times when I wish I had one of those cameras.
I always thought that in order to do thermal imaging, the sensor and surrounding surfaces had to be colder than what you are trying to measure. In the old days they did have a little refrigeration unit for this reason. If that is not the case now, how would they keep the unwanted heat out? Brian
You could try local colleges and universities, or even the local authority. They're bound to have them - whether they lend them out to non-staff is another thing. But maybe now's the time to start . . .
I chose Seek because at the time (and maybe still) the affordable FLIR devices didn't go high enough temperature for me. The FLIR devices however can superimpose a normal video image which is useful, but at the time (and maybe still) Seek didn't do that.
It seems to me that FLIR was the only sensible game in town till Seek gave them a kick up the arse.
Apart from my work (high temperature electronics) and just a bit of fun, it's proved useful for a mate looking for a blockage in his old car radiator. I suppose I could cycle round looking for cannabis farms and lost kittens.
You can create a low performance IR by hacking a normal camera. The point is that normal optical sensors are sensitive to IR light. To avoid getting very odd photos, the manufacturers include a filter that restricts the bandwidth to (more or less) the visible spectrum. If you open up the camera and remove the filter, you have a high resolution camera that picks up IR light.
That was certainly the case for the milspec stuff in the past (and may still be - I have not been in that industry for decades).
However that was a very different technology, and a very different level of performance (and price) from modern low res semiconductor based sensors.
The stuff I worked on 30 years ago used a thing called a SPRITE detector (Signal Processing In the Element) which was a strip sensor which needed cryogenic cooling to work.
With conventional TV cameras of the era, the whole image was focussed onto a photo conducting screen, and an electron beam scanned over it at TV field rate/pattern to capture the TV line data. Since the thermal sensor was just a linear strip and not a 2D array, you could not do that. Instead you needed to reflect a continuously changing tiny subset of the incoming IR image onto the sensor. This was a fairly nifty setup with high speed rotating polished hexagonal "mirrors" that would scan the image over the sensor. The whole lot had to be spun so that it was phased locked to the master TV standard scan rate to get a usable video image out the far end of it.
The result was a thermal image at full PAL resolution, with minimum resolvable temperatures down into the fractions of a degree.
The cameras have a shutter in them. I think the process is they take a picture with the shutter closed, and they have a thermal sensor on the body so they know how warm that is. Then they open the shutter and take a picture of the world, and calibrate that image based on the dark picture.
But not the full IR spectrum - possibly only to about 1um Glass as used in a normal camera lens blocks IR
The IR cameras referenced in this thread are optimised for the 8 to 12um band and probably use Germanium for the lens.
Yes but very limited by the optical lens in front of it.
Also you can replace the filter with something that blocks the visible light. When colour film was common place a filter could be made from the unexposed bit of the negative you got back from the photo processing house - the bit that looked completely black. Put one or two layers of this in from of the sensor and all the visible light was blocked. However, modifying a camera in this way doesn't give you the type of thermal camera being discussed in this thread that would show up cold spots in insulation etc.
Modern high performance 2D sensor arrays thermal cameras still need cryogenic cooling and can fitted with dinner plate size chunks of germanium for lenses
Low performance thermal cameras are optimised for room temperature operation. In this case low performance doesn't mean shit performance. They more than adequately suit the applications being discussed in this thread where they are operated in a human friendly controlled environment.
I think it was TICM II by the time I was playing with it (late 80's, early 90s)
Yup, we had a number of turret based applications with a great big variable magnification germanium telescope on the front... That alone was cost more than £100K at the time.
Oh, indeed they can be quite useful things and more than adequate for a number of use cases (spotting leaking buildings, and hot electronics being the most common).
I found with the avionics spec stuff, it had such fine temperature resolution that you could focus it on a coin on the desk, and it could "see" the queen's head on the back of the coin!
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