Concentric Light Interference
杨轶清
Award: Top 100
School: 南京师范大学附属中学
Teacher: 佳敏
Category: Contrived
Photo #19414
Concentric Light Interference
This photo was taken using a mobile phone, with a candle placed behind a CD whose central hole was covered by white paper. As the distance between the candle and the disc was carefully adjusted, a series of bright, rainbow-colored concentric rings appeared and were captured through the lens. This setup demonstrates the principle of diffraction and interference of white light.
The CD surface acts as a diffraction grating, made up of thousands of tiny, evenly spaced grooves. When white light from the candle strikes these grooves, different wavelengths of light diffract at different angles. Red light, with a longer wavelength, appears on the outer edges, while violet light, with a shorter wavelength, stays near the center. At specific angles, the light waves undergo constructive interference, creating the clear, vivid rings of color.
The white paper softens the direct candlelight and ensures a more even light source, allowing the interference pattern to appear sharply and symmetrically. Small changes in distance affect the angles of diffraction, enabling control over the ring clarity and intensity.
From an artistic point of view, the photo captures a sense of balance and mystery. The glowing, colorful rings contrast with the dark background, evoking images of a portal, an eye, or even a galaxy. It turns a simple everyday object into a visual display of light physics--where science meets art.
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