Hair Diffraction Lab

This simple, easy-to-print mount allows you to use an inexpensive laser pointer to measure the thickness of a human hair using a diffraction pattern similar to the classic double-slit experiment.

When a laser beam is directed at a hair, the hair acts like an obstacle that splits the light into two coherent sources separated by the hair’s thickness. The light diffracts around the edges of the hair and interferes constructively and destructively, creating a clear pattern of bright and dark fringes on a screen or wall.

You can calculate the thickness of the hair with surprising accuracy by measuring:
• The distance from the hair to the screen
• The spacing between bright fringes in the diffraction pattern
• The wavelength of the laser (typically printed on the laser’s warning label)

Simple, effective, and perfect for turning a low-cost laser into a powerful teaching tool!

Key Design Features

✔ Hands-Free Laser Mount
The mount holds the laser securely and depresses the power button, turning a cheap handheld or cat-toy laser into a stable tabletop laser source.

✔ Interlocking Hair Window
The hair holder (“hair window”) locks into the laser mount so both parts can be repositioned together without losing alignment.

✔ Adjustable Target Position
The hair window slides side-to-side, allowing you to fine-tune the laser’s aim after the hair has been taped in place.

Great For

• Physics demonstrations
• STEM classrooms
• At-home experiments
• Exploring wave interference and diffraction

Laser Used: https://amzn.to/49UUsQd