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Fundamentals of Engineering Presentation [LASER] Team 12

Name ID Section Omar Farag Mustafa Bayoumi 1801620 2 Mustafa Hussein Abdelhalim Rashawn 2000904 2 Abdelrahman Abdalla Ibrahim Mohamed  1801089 2 Mohamed Hatem Ali Moamen 1808665 2 Habiba Mohamed Elsayed Ali  1901225 2 Khaled Sayed Anwar Elsaid 2002045 1 Amir Samy Saad  1807249 1

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Introduction Historical Background Laser Construction Working Principles of Laser  Laser Types Laser Applications Laser Hazards and Safety Conclusion

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The word  LASER  is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser is a device that amplifies the intensity of light. When electron jumps from a higher energy level to a lower energy level, it emits light or photon.  In conventional light, excited electrons emit light at different times and directions. While, photons emitted by the electrons of laser are in same phase and same direction.

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lasers produce highly directional, monochromatic and coherent light beam. Some lasers generate ultraviolet or infrared rays which are invisible. Laser dose not subject to the inverse square law (with distance intensity decrease) as it is coherent.

"white"
light
source
chrornatic
light
source
laser
light
source

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In 1917, Albert Einstein lays the foundations for laser technology when he predicts the phenomenon of “Stimulated Emission”. In 195 0,  Charles Townes develop the quantum theory of stimulated emission and he later receive the Nobel Prize in Physics. In 1959, graduate student Gordon Gould proposes that stimulated emission can be used to amplify light with optical resonator that can create a narrow beam of coherent light.

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In 1960, Theodore Maiman builds the first working prototype of a laser. This laser uses synthetic ruby as medium. The first application for the ruby laser was for military rangefinders. In 1963, The Carbon Dioxide (CO2) laser is developed. It has much lower cost and higher efficiency than the ruby laser. These factors have made it the most popular industrial laser type for more than 50 years.

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A laser is constructed from three principal parts:

The pump source provides energy to the laser medium to produce population inversion.  Examples of energy sources include electric discharges, chemical reactions and others. energy source type depends on the laser medium.

Nd:YAG solid-state laser
Highly
reflective
Flashlamp (pump source)
ND:YAG crystal (laser medium)
Optical resonator
Partially
reflective
mirror
Laser
output

An energy source (pump source). A gain medium or laser medium. An optical resonator (Two or more mirrors that ).

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The laser medium is a medium where spontaneous and stimulated emission of radiation takes place. The laser medium will determine the characteristics of the laser light emitted. The laser medium can be solid, liquid or gaseous.

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The laser medium is surrounded by two parallel mirrors which provides feedback of the light. One mirror is fully reflective whereas another one is partially reflective. Other optical devices are used such as spinning mirrors, modulators, and absorbers to produce a variety of effects on the laser output.

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Photons are interacted in three ways with the atoms:

Absorption of radiation is the process by which electrons in the ground state absorbs energy from photons to jump into the higher energy level.

Absorption of radiation Spontaneous emission Stimulated emission

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Spontaneous emission is the process by which electrons in the excited state return to the ground state by emitting photons.

Stimulated emission is artificial process by which incident photon interacts with the excited electron and forces it to return to the ground state.

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Lasers are classified into 4 types based on the type of laser medium used which include solid state laser, Gas laser, liquid laser, semiconductor laser.

A solid-state laser uses solid as a laser medium. In these lasers, glass or crystalline materials are used. The first solid-state laser was a ruby laser. They are widely used in applications

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A gas laser is a laser in which an electric current is discharged through a gas inside the laser medium. In gas lasers, the laser medium is in the gaseous state. Gas lasers are used in applications that require laser with high beam quality and long coherence lengths.

coupler
DC power supply
Helium-Neon gas mixture
High
Glass tube

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A liquid laser uses the liquid as laser medium. A dye laser is an example of the liquid laser which uses an organic dye (liquid solution).

Semiconductor lasers is uses semiconductor materials as laser medium.  they  play an important role in our everyday life. They are cheap, compact size and consume low power.

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Laser is used in medical diagnosis, treatments, or therapies, such as laser photodynamic therapy, photo rejuvenation and laser surgery. EX: cancer diagnosis – cancer treatment – surgery – Dentistry - medical imaging, etc.

Laser radiation being delivered, via a fiber, for photodynamic therapy to treat cancer.

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Laser light is used in optical fiber communications to send information over large distances with low loss. Laser light is used in underwater communication networks. Lasers are used in space communication, radars and satellites.

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Lasers are used in electronic industries for trimming the components of Integrated Circuits (ICs). Lasers are used for heat treatment in the automotive industry Lasers are used in manufacturing (laser welding – laser cutting – laser drilling  – CNC machines). Laser printers, laser pointers. Holography.

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With the help of a helium-neon laser, it was proved that the velocity of light is same in all directions Laser is used to count the number of atoms in a substance. Lasers are used to measure the pollutant gases and other contaminants of the atmosphere. Lasers are used for detecting earthquakes and underwater nuclear blasts.

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Laser range finders are used to determine the distance to an object. Lasers can be used as a secretive illuminators for reconnaissance during night with high precision. Laser light is used in LIDAR’s to accurately measure the distance to an object.

This US military laser can identify people by their heartbeats from 650 feet away

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Improperly used laser devices are potentially dangerous. Effects can range from mild skin burns to irreversible injury to the skin and eye. Safety is only ensured when everyone has training and understanding of what occurs when a laser is applied to a patient and clinical application.

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Unintentional eye exposure during alignment. Misaligned laser beam. Lack of eye protection. Improper handling of high voltage systems. Improper restoration of equipment following service

AVOID EXPOSURE
LASER RADIATION EMITTED
FROM THIS APERTURE
DANGER
LASER RADIATION
AVOIO DIRECT EYE EXPOSURE
Max Output< 100mW
WAVELENGTH 532nm
Class 111b Laser Product

Therefore, laser safety measures must be taken.

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Safety Classes: To give some guidance on adequate handling and required precautions, laser devices are assigned to different safety classes, with class 1 being the least dangerous (containing e.g. lasers with microwatt power levels) and class 4 the most hazardous one.

Least Hazardous
Class 1
Class 2
Class 3R
Class 3B
Class 4
Most Hazardous

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Class 1
Class 1M
Class 2
Class 2M
CJZJ%
Class 3B
Class 4
Incapable of causing injury during normal operation
Incapable of causing injury during normal operation
unless collecting optics are used
Visible lasers incapable of causing injury in 0.25 s.
Visible lasers incapable of causing injury in 0.25 s
unless collecting optics are used
Marginally unsafe for intrabeam viewing; up to 5 times the
class 2 limit for visible lasers or 5 times the class 1 limit
for invisible lasers
Eye hazard for intrabeam viewing, usually not an eye
hazard for diffuse viewing
Eye and skin hazard for both direct and scattered exposure

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full or partial encapsulation of laser systems, ideally with absorbing housing materials, avoiding reflections. protective housings around dangerous areas, monitoring the presence of persons.

The risks need to be reassessed every time when important circumstances change. Reasonable ways of dealing with these risks need to be developed. This involves the implementation of technical measures.

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Lasers can be used for many applications, helped people develop in many things in our daily life. Lasers can produce a concentrated, powerful beam of light and generate associated hazards. Laser communication in space has long been a goal for NASA because it would enable data transmission rates are higher than traditional radio waves. While lasers and radio transmissions both travel at lightspeed, lasers can pack more data.  Astronomers could use lasers like very accurate rulers to measure the movement of planets with unprecedented precision.

Fundamentals of Engineering Presentation [LASER] Team 12

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