Thursday, April 23, 2009

My Research Explained: Lasers

Everyone asks, "Anthony, what do you do in your lab?" The answer is more complex than the person asking is ready for (generally), and so I just give a very quick explanation of the subject. I also realize that it can be hard to pay attention to such an in depth explanation (like I would want to give) for long periods of time. With such being the case, I present to you my short and detailed descriptions of my research:

Everyone has heard of lasers. What are they really? Well simply a laser is light that is both collimated and coherent. What do those words mean? Well, collimated light is just when rays of light are parallel to each other. Not every laser has to be collimated but most used in research are. Basically all the light emitted from the source will travel along the same line. This explains the small dot of light you see in many action movies (when the hero or villain is using a laser sighted weapon of some sort).

Coherent light involves light waves that have the same phase. Phase is just the measure of angle between waves. Every wave has an amplitude and a period. The amplitude is the height of the wave. The period is the distance from peak to peak of the wave. If there are two waves traveling together, the distance between their peaks can be measured through their phase. Two in-phase waves will constructively interefere, and out-of phase waves will deconstructively interfere. We'll save all that for another time. Anyways here is a picture of in-phase and out-of-phase waves:


So lasers are collimated and coherent. How does this work? Well honestly, I don't know. What I do know is that it works off stimulated emission. That just means you have an object that lases, some kind of material that is your source. What happens now is that the source gets pumped full of energy and the atoms from the source emit light. (This is a whole other subject.) All the light that is emitted is coherent. Then there are some mirrors in the laser and other optics that gather the light and collimate it. This is typically how a laser works.

Next time I will explain some other properties of light and lasers that allow Optical Tweezers to be possible.

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