Led Laser Light
2010
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How are the sources of an LED light and laser different if they both give red light?
Well, to be honest, they aren't all that different. A laser stands for 'light amplification by stimulated emission of radiation" and it is process where a small amount of light in a material causes the material to give off light that is identical to the light in the material. Imagine it like this : there is a factory full of women who make scarves. They can make any color of scarf. But one of them makes a scarlet scarf and all the women love the scarlet color, so they to start making scarlet scarves. Eventually, as the scarlet scarves become more common and all the women see it, everyone will be making only scarlet scarves and no other colors. Well, the factory is the laser device and the scarves are the photons of light. But, unlike women, photons never get sick of being the same as other photons.
So that is what a laser is, it is a device that makes identical photons. But a laser can be made any of hundreds of different ways. There are dye lasers and gas lasers and crystal lasers and all sorts of things. But, there are also LED lasers. An LED gives off light in a very small range of colors. But you can turn it into a laser, and it will give off light in all the same color and direction (like any laser). The difference between a regular LED and a laser LED is actually very minimal. In a regular LED, when a photon of light is given off, it is free to leave the LED and travel elsewhere. But for a laser LED, they put 99% mirror surfaces on the ends of the LED so that 99% of the photons that hit the mirror get sent back into the LED. There, they can stimulate the new photons to be identical, thus causing the laser to lase. And that's really the only difference between an LED and a laser LED. And the only difference between a laser LED and any other laser is that in a laser LED, the thing that makes the photons is an LED, while in any other laser, the photons are made by something else (in a gas laser, it's the gas; in a crystal laser, it's the crystal; in a dye laser, it's the dye; etc).
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