Remember how exciting it was the first time you took a drop of pond water and looked at it under a microscope? Tiny one-celled animals moved across your field of view and changed your ideas of small forever. It was a little creepier the first time you saw a picture of a dust mite magnified a hundredfold. This eight-legged relative of spiders and scorpions is smaller than the period at the end this sentence. It often lives in our beds, feeding on skin cells our bodies have sloughed off.

Microscopes reveal wonders like these that are too small for the eye to see. Now with lasers and other improvements, microscopes can see things that normally go on inside our cells — things like floppy proteins folding and unfolding as they pick up oxygen molecules and let them go. Picking up oxygen, carrying it to the tissues that need it, and then letting it go is what hemoglobin proteins in our red blood cells do day in and day out as long as we're alive.

Ralph Jimenez is one of the scientists at JILA. He's building a cool new laser microscope for studying proteins like hemoglobin and its cousins, the cytochromes. Cytochromes help change the energy in our food into energy for running, jumping, and thinking. It's a lot easier to understand how these proteins work if you can watch them in action. That's where the new microscope comes in.

The new microscope uses tiny liquid-filled channels only a millionth of a meter wide made out of plastic and glued to a microscope slide. Dr. Jimenez uses the channels to mix the proteins he studies with things like oxygen. Then he shines a very fast laser into the channels and takes "pictures" of the proteins picking up the oxygen. The lasers in the microscope work a lot like a camera, except a million times faster. That means they can "see" things that are very small and move very fast.

With his new microscope, Dr. Jimenez plans to study all kinds of things that happen inside cells by watching them. —Julie Phillips

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