Considering Individual Perspectives to Create a Sustainable Future

| 1/4/2010 4:12:04 PM

Evening skyI’m fascinated by holograms. We see them all the time, these days, mostly on credit cards. A three dimensional image appears on a two-dimensional surface. As you turn the credit card in your hand, the little dove on the silvery stamp in the corner turns as though it were a real object in your hand, rather than a little picture of the bird. Some credit-card holograms are tiny depictions of the Earth.

The image is not a photograph. It is not, properly, even a picture. It is a reproduction of the way light from two different perspectives is “scattered” by the presence of the object, diffracted when the two light beams interact, and then perceived from a third perspective. If we change the third perspective by turning the hologram in our hand, our eye perceives the image changing as though the object was turning.

Weird, huh?

Scientists worked for decades to create useful holograms, starting with our growing knowledge of how the human eye perceives all images — both real and reproduced — applying new knowledge of the physics of radiation in the late 1940s, then exploiting the special qualities of lasers developed in the early 1960s. Our knowledge of the physics continued to improve and lasers got cheaper and more controllable over the next decades. In March of 1984, National Geographic Magazine ran a hologram of an eagle on its cover, “embossed” on the same sort of reflective surface used on credit-card holograms, much larger and in very high resolution. Hundreds of thousands of people were suddenly holding in their hands the first hologram they had ever seen, turning it this way and that, watching the eagle turn as though it were an object rather than an image.

It was poetic that the magazine that first carried modern photographic technology into some of the world’s most remote regions would also bring holographic technology — a brand new sort of image — into the mainstream for the first time.

A photograph reproduces an image from a single perspective, the camera’s lens. The camera records the light bouncing off the scene. A hologram records the light field surrounding an object. When we look at a holographic reproduction our eyes are exploring that light field.

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