Special Light

Pure, coherent and narrow

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Laser light is monochromatic, coherent and collimated.
• Beam spread $\theta \approx \lambda / D$: wider beams spread less.
• Concentrated beams can damage eyes, so handle lasers safely.

Steps

1. Three properties
2. A laser pointer
3. The best starting width
4. A beam to the Moon
5. A laser link to orbit
6. Seeing laser speckle