LASERS By : Lucía Vicario and Tania Martín

WHAT IS IT? A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. A laser is a coherent and focused beam of photons Lasers are a special form of light. Laser light does not exist in nature. Only human technology can create laser light. The acronym laser stands for "light amplification by stimulated emission of radiation.“

HISTORY OF LASER In 1916, Albert Einstein established the basic fundaments to built a laser and a maser( microwaves). The first laser was designed by Theodore Maiman and was made of ruby. It worked for the first time in Townes and Arthur Leonard Schawlow are also considered the inventors of the laser, which was patened that same year.

DESIGN OF A LASER COMMON COMPONENTS: Active Medium: it may be a solid crystal such as ruby. It contains atoms which can emit light by stimulated emission. Excitation mechanism: It is a source of energy to excite the atoms to the proper energy state. High Reflectance Mirror: It is a mirror which reflects essentially 100% of the laser light. Partially Transmissive mirror: A mirror which reflects less than 100% of the laser light. Optical Resonator: reflects the laser beam through the active medium for amplification.

What is "ordinary" or natural light? Ordinary light, like sunlight, is made up of many different wavelengths, or colors, of light. If you put all the different colors together, you get white light.... and how is laser light different? First, the light from a laser contains exactly one color or wavelength rather than a lot of different wavelengths. Second, they are all "waving" together. Scientists say the laser light is "coherent” and "monochromatic", meaning of one color. LASER FUNDAMENTALS

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. Scientists say the laser light is "collimated.“ Laser light can deposit a lot of energy within a small area.

As 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, welding and for other uses… Bar code readers in stores use lasers. Medicine: Doctors use lasers to do delicate surgery, such as eye surgery, bloodless surgery, surgical treatment, kidney stone treatment, dentistry. Lasers carry TV and telephone signals over special cables. Metal workers use lasers to cut and weld metal into everything from street light poles to cars. Workers in clothing factories use lasers to cut through hundreds of layers of fabric at once. CD and DVD players use lasers Cosmetic skin treatments: acne treatment, cellulite and striae reduction, and hair removal. USES

ARE THEY HARMFUL? Lasers can cause a car accident beacuse the can distract or blind the driver temporarily. If a person stares into a laser, even a small one it could cause a spot on the retina. At around 150 milliwatts, the beam from a laser can be felt on the skin. At around 500 milliwatts the beam starts to burn the skin if the person is a few meters away.

HOW DOES LASERS WORK? A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become “excited.” The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atom’s nucleus. When they return to their normal or “ground” state, the electrons emit photons (particles of light).

HOW CAN WE MAKE A LASER?

QUESTIONS Who invented the laser? Name two uses for lasers What was the first laser made of?