This post continues our journey through the Mathematical foundations of iridescence. This time, we will discuss a new way in which material can split light: **thin-film interference**. This is how bubbles (and car paint) get their unique reflections.

You can find the complete series here:

- Part 1. The Nature of Light
- Part 2. Improving the Rainbow (Part 1)
- Part 3. Improving the Rainbow (Part 2)
- Part 4. Understanding Diffraction Grating
- Part 5. The Mathematics of Diffraction Grating
- Part 6. CD-ROM Shader: Diffraction Grating (Part 1)
- Part 7. CD-ROM Shader: Diffraction Grating (Part 2)
- Part 8. Iridescence on Mobile
- Part 9. The Mathematics of Thin-Film Interference
- Part 10. Car Paint Shader: Thin-Film Interference

A link to **download** the **Unity project** used in this series is also provided at the end of the page.