By: James, Jasmeet, Megan, Michelle, and Gurkirat

 A laser is a device that produces light of a single colour with all waves travelling parallel to each other.  Laser stands for Light Amplification by Stimulated Emission of Radiation

 Before lasers could be developed the quantum theory is needed to be understood especially how one electron transitions form one energy level to another  In 1971, Einstein constructed the theoretical foundation for the laser

 A photon with specific amount of energy is needed to excite the electrons so it can move to higher energy levels  The electron then returns to its ground state and releases a photon of the same energy, which forms the laser beam along with other photons  These photons all have the same wavelength and travel in parallel waves on the same path

 An energy source (flash tube) emits photons which the atoms of the ruby rod absorb.  The excited electrons in the atom then release photons of a certain wavelength.  These photons become absorbed by other atoms which increases the intensity of the light.  Some photons reflect off the mirrors and collide with more atoms, this is called the amplification of atoms.  The laser beam eventually passes through the 95% reflective mirror

 Medical applications  Garment industry  Barcode scanners  CDs and Optical disks  Welding  Communication  Cancer treatment  Skin Treatment

 The containment of a laser can be further used to focus its high energy into more practical uses of everyday life.  Although lasers pose threats to the health of an individual it can also be used to their benefit.  Such applications include laser eye surgery and the treatment/correction of cataracts. The laser acts as a cutting tool and stops retinal hemorrhaging.

 Lasers are not only useful cutting tools, but are extremely efficient when applied in communication.  For example, fibre optic cables use light signals to transfer information. This information is emitted by a laser and provides the maintenance of the “pulse” shape over time. The laser provides an overall “speedy” delivery of information, and prevents a “laggy” connection. Lasers are both dangerous and beneficial to human life and provide many useful outputs to be further developed.

Class 1 lasers  Class 1 lasers are considered to be incapable of producing damaging radiation levels, and are therefore exempt from most control measures or other forms of surveillance. Example: laser printers. Class 2 lasers  Class 2 lasers emit radiation in the visible portion of the spectrum, and protection is normally afforded by the normal human aversion response (blink reflex) to bright radiant sources. They may be hazardous if viewed directly for extended periods of time. Example: laser pointers.

 Class 3 lasers Class 3a  lasers are those that normally would not produce injury if viewed only momentarily with the unaided eye. They may present a hazard if viewed using collecting optics, e.g., telescopes, microscopes, or binoculars.. Class 3b  Class 3b lasers can cause severe eye injuries if beams are viewed directly. A Class 3 laser is not normally a fire hazard.

Class 4 lasers  Class 4 lasers are a hazard to the eye from the direct beam and specular reflections and sometimes even from diffuse reflections. Class 4 lasers can also start fires and can damage skin.