Pixel Tube

1. Fold your construction paper into equal thirds along the long axis of the paper.
2. Create a paper tube by rolling this folded construction paper and taping the ends together where they overlap. (Click to enlarge the photos below.)
    
3. Measure the height of your tube, it should be a little over 2.5 inches high. 
4. Cut many strips of the Mylar sheet of various lengths that are the same width as the height of the tube (~2.5 inches wide).   
5. Roll these Mylar sheets into tubes, and tape them so they stay rolled. They should all be about the height as the paper tube that you made (click to enlarge the photos below). Feel free to make different diameter tubes, and to vary the shapes you roll them into. (Larger tubes will naturally squash into teardrops and other shapes.)
    
6. Arrange the Mylar tubes together in the larger paper tube. You can place as many tubes as you want inside of the tube, but there should be at least enough that they hold each other in place when you lift up the tube. (Click to enlarge the photo below.)
   
7. Cut a piece of plastic cling wrap big enough to cover the top of the tube. Use a rubber band or tape to hold it in place. This clear window is there to hold the Mylar inside of the paper tube. (Click to enlarge the photo below.) 
   
8. Flip over the tube and cut a piece of wax paper big enough to cover the tube with a little to spare. Again, use a rubber band or tape to hold it in place. This will act as your viewing screen when using the pixel tube. (Click to enlarge the photo below.)
   

With the wax paper side facing you, hold the pixel tube up to various light sources and scenes—lamps, overhead lights, the TV screen, lighted signs, a sunset. What do you notice? 

The shifting shapes and patterns that appear on the screen of your light tube are the result of reflected light mixing and mingling in interesting ways. The Mylar tubes allow light to pass through either directly or by reflecting from the mirror-like walls, allowing more light to get through the tube than would normally. This extra light can make your pixel tube look as if it were illuminated from within. It also results in a surprising mix of shapes and colors, which are captured on the semi-transparent wax paper screen.

You may notice some reflections that look like swirls, or heart-shapes, or even lines that aren’t actually there. The curved shape of the Mylar cylinders causes light rays bouncing off them to converge and diverge in much the same way that a lens does, resulting in patterns of light and dark known as caustics. 

Light traveling by reflection through a cylindrical mirror isn’t just beautiful, it’s also useful. Solar light tubes are a variation on skylights that use flexible reflective tubes to carry light from the roofs of houses to less accessible spaces within, providing natural illumination where sunlight can’t ordinarily reach (click to enlarge photo below).

Try placing colored filters or other transparent colored materials in between your pixel tube and the light source. What do you notice? 

Try viewing different colored lights using the pixel tube. Is the result the same or different than when you used colored filters? Also try looking at lights of different shapes, such as long fluorescent tubes, or lights made up of arrays of LEDs. Does the shape of the light source affect the patterns you see? 

Do you notice a difference when you hold the pixel tube really close to the light source versus far away from it? 

What happens when you flip the tube around so that the cling-wrap side is facing you when you look at a light source? 

You can also try covering the plastic cling wrap with a layer of wax paper, just like on the other side. What difference does this make?

This artistic Science Snack is great for exploring how light can be reflected in different ways off of non-flat mirrors. This activity helps to investigate the light and shadow from different light sources, from different-shaped mirrors, and at different distances and angles from the light sources. Explorations of color mixing can also be conducted with this activity. 

Not only is this Snack an engaging and crafty way to get your learners to think about questions that can lead to good investigations, it can also help to build a scientific community as they share their observations with each other. It’s also a great activity for starting discussions about how art and science are related, and allows learners who are more artistically creative to have an outlet in a scientific space.

Encourage learners to raise questions about the patterns of light and shadow that they see on the viewing screen. Then help them plan and carry out investigations to answer those questions. Having different types of light sources and filters of different shapes and colors will help students to dive deeper into their investigations. If doing this activity virtually, encourage learners to think about what different sources of light they have available to them. 

Asking the questions, “What do you notice? What does this remind you of? What do you wonder? What would you like to try?” helps to create an equitable way for both shy and outspoken learners to contribute to the larger community investigation at hand.

This activity would be a nice addition to a unit on light. When thinking about light reflection, we often only discuss reflections off of flat surfaces, but this is an opportunity to investigate the more complicated reflections (and lensing) that occur with curved surfaces. An option to follow up with could be a discussion of cylindrical mirrors and anamorphic reflections.

This Snack works well for younger students, because it allows them to be creative and build their pixel tubes however they want. Asking younger students what they notice based on color, size, shape, etc. and discussing their answers can help them to build a common scientific vocabulary.

This Snack is based on work from the artist Taizo Matsumura.

Check out this episode of Build Your Own Exploratorium to see this Snack in action.