Double Slit (for laser / light experiments)

Summary

This is a 3D printable double slit that can be used in laser or other light experiments. Using a red laser (e.g. an ordinary laser pointer), you can shine it through the double slits and it makes the classic double slit diffraction pattern. This experiment result demonstrates the wave nature of light. In other experiments, light can also behave like a particle.

Overview and Background

This is a 3D printable double slit that can be used in laser or other light experiments. Using a red laser (e.g. an ordinary laser pointer), you can shine it through the double slits and it makes the classic double slit diffraction pattern. This experiment result demonstrates the wave nature of light. It is best if you have a holder for both the laser and the double slit (a floral foam block works). It is best done in a dark room, and onto a white background to see the effect the best. With this slit, the effect appears beyond about 10 feet. If you can make the slit smaller (which is difficult to do on a 3D printer), the effect should show up closer. You can shine it into a mirror if the room you are in is small to get more distance. This should support NGSS: HS-PS4-3. Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other. [Clarification Statement: Emphasis is on how the experimental evidence supports the claim and how a theory is generally modified in light of new evidence. Examples of a phenomenon could include resonance, interference, diffraction, and photoelectric effect.] [Assessment Boundary: Assessment does not include using quantum theory.]

How to perform the experiment

Please observe proper laser safety procedure when performing this experiment (e.g. do it with a fairly low powered laser, don't shine in people's eyes, etc...) The basic setup of the experiment is as follows: 

• Shine the laser through the double slit, ideally such that an equal part of the beam goes through each slit
• Allow the beam to shine at least 10 feet away on a light / white background like a sheet of paper or a wall. Further away results in a better pattern. To make the experiment better: 
• Better results can be obtained by mounting the double slit and laser into something - floral foam works fine, but the dust particles from the foam can interfere with the experiment (just clean off the laser / double slit if that happens).
• You can use a chip clip to hold down the button on the laser pointer (or use a laser that stays on). 
• You can put a piece of paper in the beam along the way and show how the beam "evolves" along the path. It at first forms the double slit pattern, and it becomes more pronounced / larger as you move further away. 
• Turning the lights out / shutting the curtains / blinds makes the effect more visible. 
• You can extend the distance of the beam (e.g. if you are in a small room) with a mirror. Shine it through the double slit, let it go across the room, bounce it off the mirror, and back to the other side of the room. Put your background here (or use the wall). If it goes well, you should see something like the image below, or better

Materials:

Required: 

• Double slit (this item)

• Fairly low power laser (a handheld laser pointer works fine - NOT the burning type - those are too powerful / dangerous)

• White or light background (a wall or sheet of paper will do) 

Optional:

• Dark area (e.g. close the curtains / turn out the lights for better results)

• Mirror (to reflect the beam)

• Floral foam (to hold the laser and double slit stationary)

• Chip clip (or other clip to hold the laser pointer button down, if applicable)

References Wikipedia Article on the Double Slit experiment

https://en.wikipedia.org/wiki/Double-slit_experiment

Note: The laser itself seems to have the diagonal light smear (it doesn't seem to be a problem with the double slit)