Lasers And Their Uses :: essays research papers

Lasers and Their Uses We have all at some point in our lives used or seen someone use a laser. They are used in compact disc players for stereos or computers, laser surgery, laser printers, holography, cutting and borring metals, communication, bar-code scanners, etc. Over the past three decades' lasers have become a tool used daily by many people and they have become very useful in scientific research. As you can see lasers are a very useful and important tool which is why I have chosen this topic to write about. The term laser is an acronym. It stands for "light amplification by stimulated emission of radiation". They produce a narrow, intense beam of coherent light. In a laser the atoms or molecules of a crystal, like ruby or garnet-or of a gas, liquid, or other substance-are excited so that more of them are at higher energy levels than are at lower energy levels. If a photon whose frequency corresponds to the energy difference between the excited and ground states strikes an excited atom, the atom is stimulated, as it falls back to a lower energy state, to emit a second photon of the same frequency, in phase with and in the same direction as the bombarding photon. This process is called stimulated emission. The bombarding photon of the emitted photon may then strike other excited atoms, stimulating further emission of photons, all of the same frequency and phase. This process produces a sudden burst of coherent radiation as all the atoms discharge in a rapid chain reaction. The light beam produces is usually pencil thin and maintains its size and direction over very long distances. Lasers vary greatly in the way they look and what they are used for. Some lasers are as large as buildings while others can be the size of a grain of salt. There are many parts to lasers. I will now explain what they are and their uses. 1) Pumping systems: The pumping system is used to transmit energy to the atoms or molecules of the medium used in the laser. a. optical pumping systems uses photons provided by a source such as a Xenon gas flash lamp or another laser to transfer energy to the lasing material. The optical source must provide photons which correspond to the allowed transition levels of the lasing material. b. collision pumping relies on the transfer of energy to the lasing material by collision with the atoms or molecules of the lasing material. Again, energies which correspond to the allowed transition must be provided. This often done by electrical discharge in a pure gas - or gas mixture - in a tube.