Laser Light Show – Illuminate Reflection, Waves, and LIDAR in Action

Bring the physics of light to life with the Laser Light Show, a captivating classroom demonstration developed in collaboration with physics educator Griff Jones, host of IIHS Crash Science in the Classroom. Using a simple laser and mirror, this activity turns core optical principles into a vivid, hands-on experience that connects directly to cutting-edge sensing technologies like LIDAR and autonomous vehicle navigation.

Turn on the laser and reflect the beam onto a wall. As you lightly tap the mirror, the dot leaps into motion — tracing mesmerizing curves. Ask students to predict what will happen and explain what they observe.

This simple setup sparks authentic inquiry. The laser beam follows the Law of Reflection: the angle of incidence equals the angle of reflection. When the mirror moves, so does the reflected beam. Because our eyes can’t track each rapid shift, our brains blend them into a continuous line — a phenomenon called persistence of vision. The same principle makes motion pictures appear fluid at 30 frames per second.

From Classroom Demo to Real-World Technology

Griff’s teaching tip also connects the activity to one of today’s most transformative safety technologies: LIDAR (Light Detection and Ranging).

Just as the mirror redirects the classroom laser, LIDAR systems use rotating mirrors to scan laser pulses across their surroundings. Each pulse reflects off nearby objects and returns to the sensor. By measuring how long the light takes to return, the system calculates distances — a direct application of the time-of-flight equation (distance = speed × time).

Repeating this process millions of times per second produces a detailed 3D “point cloud” that helps vehicles map their environment and detect obstacles. Students see firsthand how a principle they can demonstrate in the classroom literally drives modern innovation.

Bridge Physics and Perception

The Laser Light Show also creates a natural bridge to biology. Just as light reflections reveal information through LIDAR, sound waves reflect within the human ear, allowing us to perceive direction and distance. This comparison helps students connect optics and acoustics — reinforcing the universality of wave behavior in both physical and biological systems.

Why Teachers Love It

• ✅ Instantly engages students with Griff’s inquiry-driven “light show” hook
• ✅ Reinforces NGSS-aligned concepts in reflection, wave behavior, and electromagnetic radiation
• ✅ Builds real-world connections between physics, engineering, and perception
• ✅ Encourages inquiry— not passive observation
• ✅ Simple setup: only a laser, mirror, and projection surface required

Griff's Teaching Tips:

1. Use the Laser Light Show as a “hook” as you introduce light and reflection concepts.

• Open with the question: Did you know the secret to some of the laser light shows is a computer-controlled mirror that splits or aims the beam up into the sky or onto a screen?

2. Turn on the laser and show the laser’s dot reflecting off the mirror onto a wall or screen.

• Ask students to predict what will happen to the dot when you tap on the screen.

• Demonstrate the Laser Light Show (as seen in the Crash Science Demo)

3. Guide the students through a discussion of their observations.

• How did the dot make the curved patterns?

The laser reflects off the mirror as a single dot. As the mirror moves, so does the dot. Our eyes try to keep pace, but they can’t catch every split-second change. So, our brains blur the boundaries between each movement, creating a mesmerizing line that traces out all sorts of unique patterns.

It’s called persistence of vision. It’s like watching a smooth dance, rather than a series of snap shots. And it’s how motion pictures work. Your brain and eyes blend together a series of individual pictures, or frames, that are shown sequentially, very quickly – usually around 30 frames per second. The result is the optical illusion of motion.

• Did you know this technology is used to make cars safer?

• Ask students if they have heard about LIDAR sensors being used in vehicles, especially in most autonomous taxis, to help vehicles navigate and avoid collisions?

• What is LIDAR is short-hand for?

LIDAR is short for Light Detection and Ranging

• Did you know, lasers and mirrors are at the heart of LIDAR systems in vehicles?

Some vehicle LIDAR systems use mirrors, like our Laser Light Show, to disperse the laser light and detect other vehicles or obstacles.

• How can laser light detect objects?

LIDAR systems send out pulses of invisible laser light that reflect off surrounding objects and return to the sensor. The sensors use the return time of each pulse to calculate the distance to the objects. Repeating this process millions of times per second creates a real-time 3D map of the environment, called a “point cloud.” A car’s computer can use the LIDAR point cloud and similar technologies for vehicle automation and obstacle detection.

Visit the IIHS Crash Science website for more resources

Watch the Crash Science in the Classroom video on the Laser Light Show:

About Griff

"Before becoming a science education professor, I was a classroom science teacher for 20 years. I was fortunate to work at a K-12 school that allowed me to teach students of many different ages. I loved getting to see students in every grade realize that science — along with technology, engineering and mathematics — is both relevant to their daily lives and FUN!

The learning goals I had for my own classroom are the same ones the IIHS in the Classroom team has in creating this website: to inspire students, promote scientific understanding, highlight the relevance of science and foster a love of learning. Through this site, we hope students and teachers will enjoy learning and teaching about the science, technology, engineering and mathematics concepts behind vehicle crashes and highway safety. This content is especially relevant to young people who have just started to drive or will be learning to drive soon."