Science help please

I'm adam 13 and need some help with this assignment I'm doing on lasers, here's what I've done so far


Science Assignment - Light Technology and Optical Devices

Lasers

We may not realise it but lasers ( which is short for Light Amplification by Stimulated Emission of Radiation) play a significant part in making our day to day lives easier. In supermarkets bar code readers in stores use lasers. Doctors use them to preform delicate eye surgery. Without lasers TV and telephone signals could not be carried. Metal workers use lasers to cut and weld metal into everything from street light poles to cars.

The interesting thing about lasers is that the are a special form of light because Laser light does not exist in nature. Only human technology can create laser light. But first what is "ordinary" or natural light? Ordinary light, like sunlight, is made up of many different wavelengths, or colours, of light. If you put all the different colours together, you get white light. Now there are three main differences between a laser and natural light.

Firstly, the light from a laser contains exactly one colour or wavelength rather than a lot of different wavelengths. Scientists say that laser light is "monochromatic," meaning of one colour. Secondly, all the wavelengths are in phase. That is, they are all "waving" together, like a well-timed audience "wave" at a football game. All the wave crests (high points) and troughs (low points) are lined up. Scientists say the laser light is "coherent."
Thirdly, while light waves from ordinary sources (such as flashlights, lightbulbs, or the Sun) spread out in all directions laser light waves all travel in the same direction, exactly parallel to one another. This means that laser light beams are very narrow and can be concentrated on one tiny spot. Scientists say the laser light is "collimated."

Because the laser light is monochromatic, coherent, and collimated, all of its energy is focused to produce a small point of intense power. This focused power makes laser light useful for cutting and welding. It also makes it possible to control laser light very precisely and make it do all kinds of useful things.

Any comments on what I could improve or new areas I could expand on would be very much appreciated, thanks