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PBS Blog on Thermal Flashlight

PBS published a blog about our Thermal Flashlight Development this week. Check it out:

In December, Public Laboratory members made themselves a "public lavatory." Six members of the online DIY science community gathered in the well-appointed, but small bathroom of staff member Liz Barry with the lights off -- for citizen science.

Two staff members (Leif Percifield and Jeff Warren) stood in the bathtub lofting a laptop so the webcam pointed downward to capture the scene. Another (Chris Eichler) perched precariously on the sink with a camera, snapping photos of the path of light on the wall cast by the newest research tool -- a thermal flashlight. The thermal flashlight, still tethered to a computer held in Liz's lap and piloted by staff member Kyle McDonald, consisted of a non-contact infrared thermometer that reads the surface temperature of objects it's pointed at, an arduino (an open-source programmable electronics platform), one super-bright three-color LED (light-emitting diode), and a baffle to direct the beam -- a hastily constructed plastic cup covered with black tape and stuffed with thin toilet paper to defuse the light.

The light cast by the flashlight shifted from red to yellow and finally to a greenish blue as it passed over one particular tile of the wall -- I had heated this tile with a hair dryer. "This is how citizen science is done," I thought, as we all cheered to see the flashlight successfully sense the change in temperature, which the arduino computed, and output as a change in the flashlight's color. We had created a controlled environment (a dark bathroom in the middle of the day), a test situation (the heated tile), and gathered a bunch of participants and recording materials to attest to the event -- painting the wall with colors of light which told us about its temperature. We've come to call this "thermal painting."

Kyle McDonald, piloting the prototype thermal flashlight. Photo by Chris Eichler.

WHAT CAN IT BE USED FOR? The effect was captured by long-exposure photos and Glow Doodle, a free piece of software produced by MIT's Lifelong Kindergarten group. Glow Doodle was invented for people to have fun with light painting. With this combination of thermal flashlight and Glow Doodle and video or long-exposure films, Public Lab is aiming to bring low-cost thermal imaging from a bathroom to homes and communities everywhere. For instance, we're investigating whether such a flashlight can be used to spot sources of heat leakage in homes, so homeowners can take steps to improve their energy efficiency with insulation. This spring, Public Lab is working with students in Harlem to see if the flashlight can be used to document the failure of landlords to adequately heat apartments.

Like all research and development, this successful prototype was built upon the long-term work of many researchers -- both in the Public Laboratory community and elsewhere. In particular, the concept of the thermal flashlight was developed by Jeff and Kyuha Shim, a RISD Digital+Media student, in a research group Jeff and I co-directed while Public Lab was forming in 2010.

Development lagged as we focused on other research, but it was picked up and earnestly prototyped by Kyuha this fall. Kyuha, frustrated by problems programming the arduino, encouraged me to hold a workshop in my RISD class in the fall of 2011. Students in the fall class, Art:Lab, particularly Alicia Dolabaille, cracked some of those basic coding problems and published their research notes on the Public Laboratory website.

Researchers participating in the "public lavatory" workshop worked from these findings to build the successful prototype. Development of this prototype is not only proof of concept for radically low-cost thermal Imaging (the approximate cost of this prototype was $60), it is proof of concept of Public Lab's open-source collaborative approach to research and development.

PROMOTING PARTICIPATORY RESEARCH Discovery and invention are often narrated as the result of a flash of genius by one person (normally a man). But the history of science shows that discovery and invention are far more complex collaborative and iterative processes than that. Public lab, building on open-source software concepts, is seeking, like other open-source hardware initiatives, to build an open-source research and development framework that supports and encourages collective, public and participatory research and development. Our thermal imaging research suggests our open-source hardware development process has legs.

Since the "public lavatory," Public Laboratory has hosted two further development sessions with remarkable success. The second session produced four more working prototypes. This image below, produced by Jeff, shows the heat of a coffee cup on his mom's table.

Thermal Image produced by Jeff Warren using the PLOTS thermal flashlight.

Another research direction is a "fishing bob" for identifying unseen inflows into urban waterbodies. The prototype for this type of thermal imager is a thermistor hot-glued into the bottom of a take-out soup container that can be dragged through the water on a fishing pole. We're currently in the process of writing up and sharing online, detailed, freely available guides and supply lists that anyone can use to build their own thermal camera.

If you're interested in making your own thermal flashlight and participating in Public Laboratory, see the thermal imaging homepage on the Public Lab site, become a public lab member, or email

This circuit diagram for making the thermal flashlight, produced by Jeff Warren, is an example of PLOTS documentation.

Public Laboratory is excited to see what questions people can investigate using the thermal flashlight and how it might be adapted to different research directions. The thermal flashlight approach to thermal imaging can be used to create data rich-images that can be utilized as maps. These maps are easily readable and interpreted by users.

WHAT'S IN STORE We're experimenting with video, still images and software, like Glow Doodle, to figure out which data-recording approach is useful for which situation. Furthermore, the flashlight can be adapted to visualize both wide and small temperature ranges. When building the tool, you can assign which colors appear over which temperature range. You can examine temperature changes by a few degrees, or many, depending on the calibration of the range of light colors to temperatures.

One of the exciting aspects of Public Laboratory tools is that to use them, you have to build them. This means that users understand how the tools are put together, are able to adapt and adjust them to their needs. We hope, as the thermal flashlight is picked up and built and used elsewhere to address local needs, a whole spectrum of flashlights will be developed suited to a variety of uses, not to mention a whole range of beautiful images.

Thanks to everyone who participated in the thermal flashlight development including: Manpriya Samra, RJ Steinert and Andrew Anselmo. Public Laboratory is in the middle of a Kickstarter campaign to launch a retail version of aerial-mapping kits and to help fund prototypes that we can send to the community of Public Lab researchers for further development. Learn more and make a contribution here.