Groovy CDs

Groovy CDs (An exploration of diffraction from CD grooves)

Project in a Nutshell: When we see colorful patterns on the surface of a CD we are seeing the diffraction of white light with these rainbows of colors being the diffraction patterns. A CD consists of a series of evenly spaced reflective grooves that act as a diffraction grating. This project demonstrates the effect by having users shine a green laser on the CD tower thereby creating lights cast on the walls and ceilings showing these diffraction patterns. 

Concept and Evolution: This particular prototype was less of an evolutionary process than it was something I ended up doing as a backup. I was originally going to create a prototype based on magnifying glasses warping light from a string of lights, but the strong of holiday lights I bought from the store short-circuited and I had to use a back-up idea. This particular idea arose from the everyday knowledge that the face of CDs often cast a beautiful array of rainbow colors. I once did an experiment in science class years and years ago that involved shining different light sources on the CDs and observing its effects. This inspired me to create this Groovy CDs prototype. Initially I wanted to hang the CDs in a netting to create a tower-like display, then have a rotating inner motor that slowly turned the laser, and caused these diffraction lightings to appear all across the walls slowly. I thought this would be mesmerizing to watch and also interactive since any people could experience the phenomenon all at once. However, I realized that it was hard to angle the laser and CDs correctly so that the patterns were projected high enough onto the walls and this was hard to control. Instead, I decided to give users the freedom to shine the laser anywhere on the tower's exterior. If I hadn't arrived at my final product through this process, the prototype probably would not have taken on this tower shape, and would have been much simpler to emphasize the point of discovery.

Ideal Interaction: My concept of the ideal interaction would be multiple people with laser pointers who could shine lasers on the CD and cast diffraction patterns on the walls and ceilings for themselves---as well as other passersby---to notice and wonder about. As I mentioned before, I didn't make the structure a complex tower shape with lots of intent since it was originally going to serve a different purpose, but I thought preserving this structure might encourage collaboration and multiple interactions if multiple people could interact with the exhibit at once. As was pointed out, the fact that there are so many CDs obscures the point of this exhibit, and something more simple and direct would be better.

Problems and Improvements: There would be a lot of improvement if I were to move forth with this exhibit, in particular, modifying and simplifying in the prototype set up to better clarify the intent of this exhibit: what do users walk away knowing and discovering? With the CD tower set-up it becomes confusing what the interaction is, or why there are so many CDs. Instead I'd modify the set-up to only consist of 2 or 3 CDs, and a controlled laser pointer where you could project the laser on the CD. Then where the pattern projects on the opposite side, I'd have a protractor that can measure the separation between the points of the pattern and demonstrate this in relation to the distance of the back wall from the CD source. Then I would make the back wall movable so users can discover how the diffraction patterns move apart relative to the distance from the CD source.

Other ideas: As I mentioned this was actually my 2nd back-up ideas after I had material-issues with my other two (materials not arriving in mail, short-circuiting a series of lights.) Originally I wanted to play with the idea of a lightscape that could be created by bending light rays with magnifying glasses. I would have many (on the order of 100s) small magnifying classes connected to a base with flexible wires. Then users could bend then into the light, overlapping each other, and see what the effect is, as well as try to make patterns. This was inspired by an exhibit I've seen where you can bend light into arcs that eventually piece together into letters (to the right) and was fascinated by the effect. I think it would've been engaging to have users play with light and magnifying glasses, discovering how light bends as they try to reach a goal ie. spelling their own name, for instance. I actually tried to attempt this prototype for 2 weeks in a row (the next week where we made 2nd versions of prototypes I wanted to bring in this one as a 3rd) but the second string of lights I bought from Target *also* broke (all the lights blew out spontaneously when I hadn't even done anything...) so I think I'll take a break from light bulbs for now since we clearly have an antagonistic relationship...!