LASER

-Presented by Me

WHAT IS LASER? A laser is a device that emits light through a process of

optical amplification based on the stimulated emission of electromagnetic radiation.

The term "laser" stands for "light amplification by stimulated emission of radiation“.

HISTORY The first laser was built in 1960 by Theodore H. Maiman at

Hughes Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow.

LASER FUNDAMENTALS Lasers are distinguished from other light sources by

their coherence. Spatial Coherence: It is typically expressed through the

output being a narrow beam, which is diffraction-limited. Temporal(or longitudinal) Coherence: It implies a

polarized wave at a single frequency whose phase is correlated over a relatively great distance (the coherence length) along the beam.

LASER FUNDAMENTALS(CONTD..)

APPLICATIONS OF LASERS Many useful inventions use lasers. Some of which are as

follows: CD and DVD players use lasers. Bar code readers in stores use lasers. Lasers carry TV and telephone signals over special cables.

APPLICATIONS OF LASERS(CONTD..) Doctors use lasers to do delicate surgery, such as eye

surgery. 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.

LASER LIGHTS Lasers are a special form of light. Laser light does not exist in nature. Only human technology can create laser light.

HOW LASER LIGHT IS DIFFERENT FROM ORDINARY LIGHT? First, the light from a laser contains exactly one color or

wavelength rather than a lot of different wavelengths. Scientists say that laser light is "monochromatic," meaning of one color.

Second, all the wavelengths are in phase. That is, they are all "waving" together. All the wave crests (high points) and troughs (low points) are lined up. Scientists say the laser light is "coherent."

HOW LASER LIGHT IS DIFFERENT FROM ORDINARY LIGHT?(CONTD..)

And third, while light waves from ordinary sources (such as flashlights, light bulbs, 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."

HOW LASER LIGHT IS DIFFERENT FROM ORDINARY LIGHT?(CONTD..) 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 it possible to control laser light very precisely and make it do all kinds of useful things.

TYPES OF LASER HAZARDS Eye: An acute exposure to eye to lasers of certain

wavelengths and power can cause corneal or retinal burns(or both).Chronic exposure to excessive levels may cause corneal opacities(cataracts) or retinal injury.

Skin: An acute exposure to high levels of optical radiation may cause skin burns.

TYPES OF LASER HAZARDS(CONTD..) Chemicals: Some lasers requires hazardous or toxic

substances to operate.(Eg: chemical dye). Electrical: Most lasers utilize high voltage that can be

dangerous. Fire: The solvents used in dye lasers are flammable. High

voltage pulse or flash lamps may cause ignition. Flammable materials may be ignited by direct beams.

LASER HAZARD CLASSES Lasers are usually labeled with a safety class number,

which identifies how dangerous the laser is: Class 1 is inherently safe, usually because the light is

contained in an enclosure, for example in CD players. Class 2 is safe during normal use; the blink reflex of the eye

will prevent damage. For example laser pointers. Class 3R lasers usually involve a small risk of eye damage.

Staring into such a beam for several seconds is likely to cause damage to a spot on the retina.

LASER HAZARD CLASSES(CONTD..) Class 3B can cause immediate eye damage upon

exposure.

Class 4 lasers can burn skin, and in some cases, even scattered light can cause eye and/or skin damage. Many industrial and scientific lasers are in this class.

ADVANTAGES OF LASER The laser can be used as a precise cutting tool. Lasers also allow the clinician to reduce the amount of

bacteria and other pathogens in the surgical field and in the cavity preparation.

Lasers used for dentistry takes shorter procedure times.

DISADVANTAGES OF LASER Laser have high power consumption. Laser can be expensive. In laser, rate of production depends on the material. Poorly adjusted lasers can cause burning. 

CONCLUSION Lasers can produce a concentrated, powerful beam of light

and generate associated hazards.  Lasers are device which amplify light and produce beams of

light which are very intense, directional and pure in color. Lasers can be used for many applications, helped people

develop in many things in our daily life. However, safety precautions should include all the control

measures.

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