Laser Light Shows
Geometry & Trigonometry
Work out the mirror angles and beam paths that let a single laser draw shapes and letters in the air.
Introduction
Laser light shows draw shapes and text in the air by bouncing a single laser beam off one or two fast-moving mirrors (galvanometers), redirecting the beam many times a second. The position of the beam on a screen or in fog depends on the angles of the mirrors at that instant, and drawing a smooth circle or a shape means rotating the mirrors through a precisely timed sequence of angles. This exploration asks you to work out the beam geometry for a simple venue setup, and the mirror angles needed to draw simple shapes.
Guiding Questions
- A laser show draws shapes with a moving beam. How does the beam position relate to the mirror angles?
- Using distances in the venue, compute the beam path lengths and angles for a simple figure.
- How fast must mirrors move to draw a circle at a given size? Use angular speed.
- Design a two-mirror system to draw your initials. Plot the mirror angle functions over time.