Shedding Light on a Rainbow Flare
Angela Yu
Award: Top 100
School: trinity school
Teacher: mark schober
Category: Natural
Photo #21279
Shedding Light on a Rainbow Flare
On a snowy morning, I was photographing the breathtaking scenery in Central Park when I noticed a strange circular flare on the top right corner of my image. It appeared as a bright, multicolored ring streaked with yellow, teal, orange, and magenta. Although it resembled a natural rainbow, the colors didn't come from the sky -- they were born inside my phone's camera lens assembly.
When intense sunlight passes through a camera, most of the light goes directly to the sensor to form the image. However, a small fraction of the light bounces off the camera's many internal layers, including the anti-reflective coatings. When light hits these extremely thin coatings, some of it bounces off the top layer while some bounces off the bottom layer, creating a front and a reverse surface reflection and minimizing reflections. But when the camera is tilted at an angle, the optical path length through the coating changes. Depending on their wavelength and the angle of the incoming light, some waves reinforce each other through constructive interference, while others weaken through destructive interference, resulting in unique colors in different parts of the flare.
In my photo, the intense sunlight and angle combined to create the beautiful array of crimson, turquoise, and yellow contained within a soft curve. My walk in the park gave me a new understanding of how cameras interact with light -- shedding light on the invisible physics behind a single click.
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