On Science Friday, a weekly science program on NPR, they featured a video that demonstrated the polarization of light bouncing off of melting ice. Edward Aites, a videographer and a photographer specializing in time-lapse image capture, said he was looking for something to explore in his studio during the winter months and started playing around with ice. The results are mesmerizing.” “Look at frozen water through cross-polarized light, and zoom in with a macro lens, and you’ll find a colorful and intricate landscape.
The video is an interesting exploration of the nature of color. First lets talk a little about the definition of polarization. Polarization is essentially the orientation of a wave of light. The polarization changes as the light wave rotates in space. In the case of the camera, a polarizer is applied to the front of the lens which organizes all the light entering the camera in to a single angle of orientation. Confusing? Here is a great visual explanation from the WikiMedia commons.
As the light travels from one side of the polarizing plate to the other, in this case right to left, the plate reorients the light.
But what effect does polarization have on color? The primary effect of polarization in photographs is to reduce reflections and scattered light, giving images clearer richer color. For example the image below, also from WikiMedia, compares two images of vegetation with and with out a filter. On the left a rich verdant green is revealed when the polarizer is applied, where as on the right the greens appear muted and visually muddled together.
Another great example of the effects of interrupting a single wave of light and causing it to rotate is evident in the color of the sky. Normally when we look at or take pictures of the sky we capture lots of light that has bounced between molecules in the air, creating lots of hazy reflections we don’t even notice. But when the polarizer is present, blue abounds and clouds pop out from the background.
– Jill Pilaroscia, Principal, Colour Studio