lightboard.info

The Lightboard is a glass chalkboard, pumped full of light.  It's for taping online lectures. Your writing on the lightboard is bright and readable, and you face toward your students.

 
Lightboard is offered as Open Source Hardware by 
Michael Peshkin, Northwestern University (September 2013.) You are welcome to use it freely. Please let me know of improvements

Here's a one-minute video intro to the Lightboard.


I'm a professor of mechanical engineering. In the classroom I use a chalkboard for drawings and equations. Recently I've wanted to tape short lectures for my electronics design course, both for online education and for flipped classes. ("Flipped" or "hybrid" classes means that students watch lecture material online, in advance, so that we can use classroom time for more valuable interactive activities.)

Filming a chalkboard or whiteboard lecture results in a dismal video. Good video lectures have usually gone through a lot of post-production editing to merge a video of the instructor speaking to the camera, with graphics to illustrate the material. Nice, but time consuming.

Moreover, while teaching, I work the board. A lot. I point to terms in equations, illustrate movement in diagrams -- I talk with my hands! It's natural for humans and maybe also for chimps to "follow the hands."


I needed a technology that lets me draw highly visible sketches and equations as I lecture, lets me work with my drawings in a natural way, lets me face the camera, and captures video of good quality without a lot of post-production editing. Also, it wouldn't hurt to be able to superimpose computer-generated graphics, such as videos or powerpoint slides. And if I can superimpose graphics, I need to be able to watch myself in a monitor in order to point to the graphics or draw on them.

That's why I developed the Lightboard. The Lightboard consists of a 4x8 foot panel of architectural glass, lit internally from the upper and lower edges by bright white LEDs. Light travels to all parts of the glass by total internal reflection (TIR). Below you can see the beam of a green laser pointer bouncing up and back through the glass, reflecting from the inside surfaces by TIR. This pattern continues for the whole eight feet across the panel. It is very clear glass! 


I draw with fluorescent dry-erase markers on the glass. The marks glow brightly due to their illumination via frustrated total internal reflection (FTIR) by light from inside the glass. Generally the light stays in the glass (total internal reflection), but it escapes wherever a material is within about a wavelength of the surface (frustrated TIR). That material can be marker ink, or it can be skin that is pushed into close contact with the glass: