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Diy Thermal Flir Project


MattGyver

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I'm back.

 

It's been several months since I've posted anything on here. I assure you, it's been worth the wait to see what I've been up to.

 

Lately, I've been playing with the FLIR Lepton thermal camera. In case you didn't know, the FLIR Lepton is the smallest thermal camera.....pretty much ever. Smaller than the size of a dime, the sensor has a resolution of 80x60 pixels and costs less than most entry-level airsoft guns. You can read more about the Lepton here. The Lepton can be bought from Digi-Key, GroupGets Store, and SparkFun (comes with breakout dev kit).

 

lepton_campaign_image.png

 

See what I mean? It's pretty amazing:

 

Flir Lepton Selfie

^^^^^^^THERMAL SELFIE

 

Seeing as I've built a night vision optic or two before, I felt up to the task of making a DIY low-cost thermal vision solution for airsoft. The resolution isn't great, but get over it. It's thermal vision, which from what I've seen is basically the holy grail of optics for airsoft. If you want pixels, they come at a high price (and 80x60 ain't that bad). Even more than night vision, you don't need to screw around with any pesky IR illuminators, oversensitive image intensifier tubes, and you get basic life detection which night vision on its own does not do. Plus you can see through most smoke (I think fog or mist is the exception since it's water).

 

Why build it? There are other combat ready products out there that use the Flir Lepton family of thermal camera sensors (Such as the Torrey Pines Logic Mini thermal sight product line-I think priced around $600-800). When you build your own however, you have much more power and control over the system (including the enclosure and form-factor). It becomes possible to develop a truly modular system that could be RIS compatible, helmet integrated, or simply mounted to a grip for general purpose thermography. You could also by a new gun with the money you're saving to slap that thermal optic onto when you're done.

 

Thermal-Imaging.jpg?616f59

 

Of course, the Lepton is just the sensor, not the entire optic. You need to have a breakout/dev board to process and buffer each frame. You also need to send the frames to some sort of display, such as a TFT or an OLED screen. Finally, you need buttons for changing gradients, toggling the Auto Gain Control (AGC) getting radiometry data, and so on. Oh, and you need to program all of this in by the way (still figuring that little detail out).

 

So I started by picking up a Lepton and a breakout board from Sparkfun (on Cyber Monday) for a touch over $200.

 

$200 base cost for basic thermal vision.

 

Let that sink in.

 

 

Sparkfun Flir Dev Kit: https://www.sparkfun.com/products/13233

 

13233-011.jpg

 

^By the way, that board is literally 1x1 inches in size. Tiny!

 

The Sparkdun Dev kit board basically sends the Lepton data over SPI to another board (Raspberry Pi reports the highest success with this). The problem with the Raspberry Pi is that the board requires sometimes a lengthy boot up time, connecting to any external TFT/LCD display over SPI gets complicated due to SPI usage from the Lepton, and worst of all-often times the Lepton will fall out of sync and hang. Restarting the Lepton will show a "red box" error (literally displaying a red box in the corner of the window). The only way to correct this is to surgically extract the Lepton sensor from the board socket like some kind of tumor and replace it while being powered. Conclusion: I will not be using the Raspberry Pi.

 

So, I did some more looking and decided to try an alternative-The Pure Thermal 1 Dev board by Pure Engineering:

 

Link:http://www.pureengineering.com/projects/purethermal1

 

PureThermal1.jpg?height=400&width=400

 

Price point on this is a bit higher than a Pi (much higher) at $110. The board is still the same 1x1" form factor as the SparkFun kit, however this board includes much more. The PT1 includes an STM32 microcontroller that does the image buffering. The board is also powered over USB and has headers for UART/IC2 for sending the data to a display (hopefully). There is the STM32 Nucleo board (Arduino compatible and $11-15), however the form factor wins on this one; also, there is an analog board by FlyTron in the UK for drone use with the Lepton, however you are limited to grayscale palattes and the cost is doubled from that of the PT1. I still might go back to the Nucleo once I get the first iteration of this project working.

 

Of course, this board is MUCH harder for me to program. Still doable though. And duh, I'll 3D print an enclosure. It might be possible for me to overlay thermal video over color video from a normal board camera to get the best of both worlds, but I'm keeping this simple at first. I think Torrey Pines Logic had the right idea with their form factor-cube-like. You can always toss on a FTS magnifier if the picture seems too small. It could be useful to use beamsplitters from the thermal display (possibly magnified) for using with red dots and scopes.

 

Let me know if you have any ideas for this so far. General feedback is welcome. Also, feel free to show or link photo references for form factor designs I should be considering. I still like the cube-shaped form factor due to its simplicity and ease of making the system modular.

 

-MG

 

 

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For distance, I'm using the 50° FOV version (they make a 25° FOV version that's I think around $40 more as well; I haven't read too much into the 50° shuttered version). I actually haven't tested it outside yet, but I assume the distance should be good enough for airsoft if not even better. Hopefully should be around several hundred yards.

 

That's why I'm tempted to use a higher resolution display, use an additional 50° color CMOS camera, and overlay the scaled thermal image over the higher resolution color output in order to obtain a better spatial awareness.

 

From what I've read, temperature range is from about -10° C to 65° C at .05° C sensitivity and can automatically adjust itself if AGC is enabled. For example, I can be in the frame and appear yellow hot, but if even one pixel of a much hotter object enters the frame (say a cup of hot coffee), the software will adjust itself and I will look not too indistinguishable from background heat. Not super useful for airsoft, but quite handy for general purpose thermography since you can see the hottest thing in frame. Radiometry can be enabled, but I just need to find where people are, not measure their body temperature.

 

I think I might even be able to get 10 fps on the video output (which isn't too bad). :)

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Glad to see you back. Looking forward to more of your neat ideas!

 

By the way, have you considered stuffing the guts of one of your NV systems into those decorative NV devices? I would assume that would mean easy interfacing with helmet mounts.

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Yes. Well, I've technically downloaded scale CAD models of PVS14 monoculars and the biggest issue is always getting the display to fit (square screen meets smaller tube). I did manage to reduce the size of my last digital system quite nicely and it looks fairly similar to a PVS14 style optic. I would imagine that modifying it would be easier to do if you have an i2 tube and a power supply to modify the enclosure, but 3D printing makes modifying replica optics enclosures completely unnecessary. :) I can also print with flexible materials (NinjaFlex TPU filament) to make flexible rubbery parts such as the rubber eye boot, DIY O-ring seals, gaskets, and flexible button covers.

Edited by MattGyver
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Hnnnnnnghh! NinjaFlex!

I can only run basic polymer type Fdm in the one I have access too :(

 

I never thought of using Thermal for a reflex sight, that's quite clever.

Edited by ProPainTank
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Ninjaflex is one of the most rewarding and equally infuriating materials to 3D print with. It sticks to everything, so its almost guaranteed to murder your kapton tape printing surface unless you're printing on a glass plate. I had to print a few parts to modify my extruder block in order to print with it. You might be better off just doing a two-part silicone mold from a rigid printed part if you need it flexible.

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