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laserlab
so what is a laser?
L – ight
A – mplification by
S – timulated
E – mission of
R – adiation
A laser is a device that multiplies light. However the light has a very special quality – it is monochromatic. That means that the light has only one wavelength.
Light from the sun is made up of lots of different wavelengths. When you let light go through a prism it is split up into lots of different colours. If you pass laser light through a prism it does not split up into different colours.
Laser light is used at clubs and rock concerts to produce lighting effects, but they have lots of other uses.
The great thing about lasers is that they can be very intense, very accurate – with a narrowly defined beam of various strength.
So a Laser light can be used for cutting materials that are too hard to be cut conventionally, or in surgery to cut away diseased tissue without damaging delicate surrounding tissue.
lasers are also used:
- as pointers in lessons and lectures
- for communications – carrying digital data files along fibre optic cables
- for music – lasers are used to read the information on CDs (Lasers read the pits in the surface of the CD. The pits are tiny and a typical CD player has to read over 40,000 pits per second!!)
- in supermarkets – to identify bar codes
- to measure distances accurately
- to listen to private conversations...
how can a laser be used to listen to conversations?
Because laser light is coherent, that is all the waves are lined up, it is possible to use laser light to measure distances, and differences in distances.
When we speak the air vibrates, and glass in the windows of the room we are in will vibrate too. By splitting laser light into two and firing one half of the beam at the window the reflected beam is affected by the vibration of the window.
If you recombine it with the other half of the beam it is possible to work out what has been said to produce that specific pattern. Even more amazingly you can listen to conversations many miles away, as the laser light will travel a long way.
are lasers dangerous?
Lasers can be very dangerous.
Because the light is very concentrated it can cause burns to your retina if you look at it directly.
There are strict guidelines about the use of lasers and each has a specific power rating. Usually lasers used as pointers have a low power rating, but it is not safe to direct this light into the eyes.
Some lasers emit light in the infra red part of the spectrum. The CO2 laser is very powerful and also dangerous – you can’t see the light but it melts anything it comes into contact with!
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