DIY Thermal Imaging Camera: How to build a Less-Expensive One

What is a Thermal Imaging Camera?

A thermal imaging camera, also known as an infrared camera or thermographic camera, is a device that creates an image using infrared radiation, similar to a common camera that forms an image using visible light. Instead of the 400–700 nanometre range of the visible light camera, infrared cameras operate in wavelengths as long as 14,000 nm (14 μm).

Thermal imaging cameras detect the heat emitted by an object and convert it into an electronic signal, which is then processed to produce a thermal image on a video monitor and perform temperature calculations. They are useful for a variety of applications, including building inspection, firefighting, medical diagnosis, and scientific research.

Key Components of a DIY-TIC

To build your own thermal imaging camera, you’ll need the following main components:

In addition to these main parts, you’ll also need some connecting wires, a breadboard or protoboard for assembly, and miscellaneous small components like resistors, headers, and mounting hardware. Budget around $20-50 for these.

v DIY-TIC Assembly Process

Once you’ve gathered all the necessary parts, it’s time to put your DIY thermal camera together:

1. Connect the microbolometer sensor to the processing board using the appropriate interface (often SPI). Solder headers or use jumper wires.

2. Similarly, connect the visible light camera to the processing board. The Raspberry Pi Camera uses a dedicated MIPI CSI-2 interface.

3. Wire up the display to the processing board’s video out. For an HDMI monitor, this is straightforward. Other displays like LCDs may require additional drivers or adapter boards.

4. Put together the battery and power management circuit to provide the required voltages to the components. Use a lithium battery and boost converter for 5V, and additional regulators if needed for 3.3V and 1.8V.

5. Assemble the components into the enclosure, making sure to secure them and allow access to ports, buttons, and the display. You may need to design custom mounts or use standoffs and nuts and bolts.

6. Load the necessary software onto the processing board. This includes the Linux operating system, drivers for the sensors, and any custom image processing code you’ve written or downloaded.

Software and Calibration

A major part of getting your DIY-TIC working is the software side. You’ll need to integrate the drivers for the microbolometer array and visible light camera, and develop an image processing pipeline to convert the raw sensor data into a usable thermal image.

Some key software steps:
– Install the Linux OS (e.g. Raspbian for Raspberry Pi)
– Enable the camera interface and check that both cameras are detected
– Load or write the driver for the thermal sensor
– Capture raw data from the thermal sensor and convert it to a thermal image
– Overlay the thermal image on top of the visible light feed
– Implement false color mapping to visualize temperatures
– Add any UI elements like a temperature scale, spot measurements, or recording

There are some open source projects and libraries that can provide a starting point, like the MLX90640 Arduino library or the Lepton RaspiCam software for FLIR Lepton sensors. However, integrating everything together will likely require some custom coding in Python or C++.

Calibration of the thermal sensor is also important for getting accurate temperature readings. Most microbolometer sensors come with factory calibration data that needs to be loaded and applied to the raw output. You’ll also want to periodically check the calibration with a reference heat source.

Using Your DIY Thermal Camera

With the hardware assembled and software loaded, your DIY thermal imaging camera is ready to use. Point it at objects of interest and observe the live thermal view on the display. You can look for hot and cold spots, compare relative temperatures, and even estimate absolute temperatures if your camera is properly calibrated.

Some interesting subjects to examine with your thermal camera:
– Electrical panels and wiring for hot spots that could indicate loose connections or overloaded circuits
– Walls, windows, and insulation to find areas of heat loss
– Mechanical equipment to check for abnormal friction or overheating
– Humans and animals to observe skin temperature variations

Remember that thermal imaging doesn’t see through walls or most objects – it only detects infrared radiation emitted from the surfaces it can directly see. Glass and shiny metal surfaces can also be tricky due to their reflectivity in the infrared spectrum.

Conclusion

Building your own DIY thermal imaging camera can be a fun and educational project that provides a useful tool at a more affordable price than commercial thermography equipment. With some patience and troubleshooting, you can assemble a functional thermal camera that combines a microbolometer sensor, visible light reference, and image processing to let you see the world of heat all around us.

The skills and knowledge gained from a DIY-TIC project can also open up further avenues for exploration, like using machine learning to analyze thermal images, or integrating thermal sensors into robots and drones. What will you discover with your homemade thermal imaging camera?

FAQ

1. Q: How much does it cost to build a DIY thermal imaging camera?
   A: The total cost can vary depending on the specific components used, but expect to spend around $300-800 for a basic DIY-TIC setup. This is still significantly less than commercial handheld thermal cameras which often start at several thousand dollars.

2. Q: What skills are needed to build a DIY-TIC?
   A: Building a thermal imaging camera requires some comfort with electronics assembly (soldering), using single-board computers like Raspberry Pi, and programming in languages like Python or C++. Familiarity with digital imaging concepts and Linux is also helpful.

3. Q: Can a DIY thermal camera be used for professional applications?
   A: While a homemade thermal camera can be suitable for many hobbyist and educational uses, it may not have the resolution, sensitivity, and reliability needed for professional thermography in fields like industrial inspection or scientific research. Commercial certified thermal cameras are still the best choice for critical applications.

4. Q: Are there any safety concerns with using a DIY-TIC?
   A: The main safety issue is electrical, as you’re working with powered electronic components. Be sure to properly insulate connections, use the correct voltage ratings, and avoid shorts. Also, be cautious when pointing the camera at very hot objects or bright light sources to avoid damaging the sensor.

5. Q: How can I improve the performance of my DIY thermal camera?
   A: The thermal resolution and sensitivity are primarily limited by the microbolometer sensor specs. However, you can improve the usability by refining the software for better image processing, adding features like recording and analysis, and optimizing the power management for longer battery life. Upgrading the enclosure and optics can also enhance durability and thermal image quality.