
Building a Thermal Camera - jjwiseman
https://damow.net/building-a-thermal-camera/
======
electrograv
Based on the title and opening paragraph, I excitedly thought this would cover
the manufacture of the sensor or lenses — you know, the things without which
you don’t have a camera at all.

Perhaps a more accurate title would be “Salvaging a broken ‘FLIR One’ to make
a thermal vision scope!”

Still a very cool project! Too bad it’s not reproducible at this cost though
(this was more affordable than commercial products only because the author
managed to buy a broken ‘FLIR One’ cheap on eBay, and salvage the sensor).

~~~
anfractuosity
I have seen projects where people created scanning thermal cameras,
repurposing one of those IR thermometers I believe, such as -
[https://www.youtube.com/watch?v=5v61Kuaxab0](https://www.youtube.com/watch?v=5v61Kuaxab0)

As far as I know the sensors used in thermal cameras don't use silicon due to
the long IR wavelengths they're detecting and instead use something like
InGaAs iirc, so I assume making your own sensor would be very difficult.

However possibly you could make your own thermopile array instead -
[https://en.wikipedia.org/wiki/Thermopile](https://en.wikipedia.org/wiki/Thermopile)
? I'm not sure how they compare to the sensors normally used though.

Edit: Also
[https://en.wikipedia.org/wiki/Microbolometer](https://en.wikipedia.org/wiki/Microbolometer)
seems like you can use silicon + another layer to handle the IR

~~~
wl
InGaAs is for near infrared. The long-wave IR used in thermal imaging requires
something like vandium oxide.

~~~
anfractuosity
Ah gotcha cheers. I was looking at an InGaAs sensor for around 2um for alcohol
measurements a while ago, I didn't realise body heat etc. would require longer
still.

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jotux
If you want to do the same thing the sensor is ~$250. You can get one on a
devboard from sparkfun for $260:
[https://www.sparkfun.com/products/13233](https://www.sparkfun.com/products/13233)

Adafruit has a low-resolution thermal sensor (8x8 pixel) for $40:
[https://www.adafruit.com/product/3538](https://www.adafruit.com/product/3538)

~~~
Game_Ender
The SparkFun sensor is the Lepton 1 with 1/4 the resolution of the Lepton 3
(80x60 instead of 160x120). He really did get a great deal on the sensor!

A quick google search shots GroupGets [0] has a Lepton 3 sensor, no breakout
board for $240.

0 -
[https://groupgets.com/manufacturers/flir/products/lepton-3-0](https://groupgets.com/manufacturers/flir/products/lepton-3-0)

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mtw
This relies on finding an affordable Flir camera on eBay - I checked and you
can't find anything under $100. If you want to build your own, it will turn
out as more expensive if not more expensive than buying it from FLIR

~~~
verifex
I was expecting a little more in the actual optics creation portion of this
article, but it is sadly predicated on us finding a really value priced FLIR
camera sensor, which is not a small order. I've looked at these in the past
and the price always pushed me away.

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kachurovskiy
This is an awesome project and I'm very impressed with the skill levels
demonstrated, especially the video pipeline.

If you just need a thermal camera though, there's a 120 EUR one on AliExpress.

[https://www.aliexpress.com/item/HT-02D-Handheld-Thermal-
Imag...](https://www.aliexpress.com/item/HT-02D-Handheld-Thermal-Imaging-
Camera-Infrared-Thermometer-IR-Thermal-Imager-thermometre-infrarouge-
termometro-infravermelho/32833904540.html)

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tgb
If you ever get the chance, do try playing with a thermal camera! It gives you
a whole new appreciation for the great that flows around us that I never was
able to grasp from a physics class. You can actually see footprints and even
can write on the wall just by dragging your warm fingers against it. It's
really incredible!

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mattmoss
Would this be a good tool for finding air leaks (i.e. cold air coming in
during the winter) in an old house? I might drop the $200-300 for one of these
if it will help me find all the leaks.

Even better if the $40 Adafruit one mentioned elsewhere
([https://www.adafruit.com/product/3538](https://www.adafruit.com/product/3538))
worked just as well, once configured/programmed adequately.

~~~
rbritton
I bought one for that purpose. What it does best is show you relative
temperature levels, which you can then investigate further to see if they're
real or not. In my experience, some are actual air leaks, some lack of air
circulation, and some lack of backing insulation.

~~~
tonyarkles
Yup, definitely agree. I've got one of the Seek Thermal units, and while the
absolute temperature measurements aren't always that accurate, the relative
temperature measurements are _fantastic_ for finding hot/cold spots.

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kabouseng
Next up is doing your own nuc[1] and upscaling the image using bilinear or
biqubic upsampling [2]. Enjoy :-)

[1]
[http://www.flir.com/cvs/cores/knowledgebase/index.cfm?CFTREE...](http://www.flir.com/cvs/cores/knowledgebase/index.cfm?CFTREEITEMKEY=353&view=67111)

[2]
[https://en.m.wikipedia.org/wiki/Image_scaling](https://en.m.wikipedia.org/wiki/Image_scaling)

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kevin_b_er
If trying to seriously build a thermal camera and you're in the US, keep in
mind US export laws. IANAL, but there's some nasty restrictions if the the
thermal cam's resolution or Hz are too high. Then they become like weapons
under the law and export becomes heavily restricted. FLIR almost certainly has
an entire team dedicated to making sure they don't make US customs angry.

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joshvm
For a low resolution (8x8) option, there's Panasonic's GridEYE. It's good
enough for basic area thermal imaging, though not nearly as useful as a high
res sensor. It is only £30 or so though.

Depending on the object temperature, you can also use Silicon or Calcium
Fluoride which will work up to around 8um. Humans emit at around 12um though.
CaF2 has the advantage that it'll also pass NIR/visible/UV light down to 180
nm.

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olegkikin
Being a programmer, but not an engineer, I always wanted to try to create a
camera with the ability to micro-shift the sensor in both directions,
increasing the resolution. If you shift 3 times by 1/3 of the pixel on each
axis, you can theoretically 9X the resolution (well, megapixels). Of course,
it won't work for dynamic scenes, but could be quite useful for industrial
scanning or looking for house insulation problems.

~~~
matte_black
Nope won’t work, the image is not an orthographic projection.

~~~
blattimwind
This absolutely works, but not quite the way GP described. Instead, unit
motions on the bayer pattern are used, to the effect that every _logical_
subpixel is sampled by every colour channel (therefore giving you a full
pixel). Hence, no demosaicing is required. Hence, higher spatial frequencies
can be maintained without incurring aliasing.

~~~
red75prime
It is also possible to actually increase resolution.
[https://arxiv.org/abs/1706.06266](https://arxiv.org/abs/1706.06266)

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Posibyte
If you don't mind the bitbanging, Software SPI could totally be an option for
your resistive touchscreen if the screen itself isn't a super active device.

Also, for the camera itself, way, way cool. I love the idea of stumbling on
hidden gems in the rough and polishing them into a nice ring.

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kepano
Face ID makes use of a front-facing IR sensor and dot projector. I hope those
sensors make their way to the back of smartphones too. Could enable some very
neat apps.

~~~
ClassyJacket
I predicted 3D sensors coming to phones a few years ago, but what I got wrong
was that they ended up on the front, not the back. I do hope they make their
way to the back as well. If they can do it with a big enough distance cutoff
to work in any average sized home room, ARKit will look like a stupid toy in
comparison.

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afarrell
This is super cool!

However, I do note that once FLIR devices become commonly available in the US,
it will be constitutional for the police to use them to spy on your in your
home and then use the resulting evidence against you in court.

[http://lawcomic.net/guide/?p=2201](http://lawcomic.net/guide/?p=2201)

[https://en.wikipedia.org/wiki/Kyllo_v._United_States#Opinion...](https://en.wikipedia.org/wiki/Kyllo_v._United_States#Opinion_of_the_Supreme_Court)

~~~
gameshot911
Well, yeah, you're breaking the law and these devices provided and advanced
way to prove it.

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agumonkey
a nice video about bolometer arrays
[https://www.youtube.com/watch?v=LFIUpvcmQLU](https://www.youtube.com/watch?v=LFIUpvcmQLU)

