A DIY Thermal Imager the Size of a GoPro
Ruslan's DIY Pocket Thermal Imager is the size of a GoPro camera, but offers impressive specs.
Thermal imaging is very useful for a wide range of tasks. Want to see where the leak is in your HVAC duct work? A thermal imager can help. Want to find hot or cold spots on your 3D printer's heated bed? A thermal imager can help. Want to see if your engine headers are heating evenly? You guessed it: a thermal imager can help. If you're the do-it-yourself type and want one, then check out Ruslan's DIY Pocket Thermal Imager that is about the size of a GoPro camera.
This is a nice and compact, self-contained thermal imager that includes only the features you want. Its built-in LCD screen shows you the thermal view and the temperature range. It has a resolution of 32x24, which is pretty decent for thermal imaging. Government regulations prohibit high-resolution, high-speed thermal imaging sensors anyway (it has something to do with preventing missile guidance systems), so there is an upper limit no matter how much money you spend.
The key component in this project is a Melexis MLX90640 thermal imaging sensor, which contains 768 infrared sensing elements and some built-in processing capability. It communicates via an I2C interface. There is an evaluation board available to connect the sensor directly to a computer, but Ruslan wanted a standalone package. They chose to pair the sensor with a TTGO T4 module.
The TTGO T4 is a handy bit of hardware that combines an ESP32, a 2.4" full-color LCD screen, a microSD card slot, and a lithium battery charging IC. Ruslan put the thermal imaging sensor on a perfboard, connected it to the TTGO T4, and sandwiched a 600mAh lithium battery between the two boards. Those all fit inside of a custom 3D-printed enclosure.
That took care of the hardware and everything else was software. Ruslan chose to run FreeRTOS, which is a lightweight operating system for embedded applications. It runs on the ESP32 and Ruslan programmed the software on top of FreeRTOS. The interface is in Russian (Ruslan's native language), but this is an open source project and users can change the language if they like. The software interface is very nice and displays the frame rate, battery level, thermal view, temperature range, and data points. Using the TTGO T4's built-in buttons, the user can change parameters or see additional data.
While there are inexpensive consumer thermal imagers that offer similar performance, this is a nice open source project that anyone can hack as much as they'd like.
