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Transcript of The Laser
Radiation General Characteristics Monochromatic Collimated Coherent One "single" color or wavelength.
The light is extremely pure and unique The beam spreads very little over long distances. (extremely parallel) The individual waves of light are
traveling precisely together through
time and space. Therefore, they are IN
PHASE A Brief History
of the Laser Max Planck discovered
the relationship between energy and the frequency of radiation. 1900 1905 Einstein releases his work on the photoelectric effect. 1917 He proposed the process that made
a laser possible. Stimulated
Emission 1951 1954 Charles H. Townes thought of a maser (microwave amplification by stimulated emission of radiation) on a park bench. First maser constructed at Columbia University in New York. wavelengths of 1 cm
generated approx 10 nW of power May 1960 December 1960 Theodore H. Maiman constructs the first laser
using a cylinder of synthetic ruby. Bell Labs develop the helium-neon (HeNe) laser, the first to generate a continuous beam of light at 1.15 micrometers. 1961 Lasers begin appearing on the commercial
market. December 1961 The first medical treatment of a retinal tumor was done using a ruby laser to destroy the tumor. 1962 Laser power is 100 times stronger than ruby laser thanks to Fred J. McClung and Robert W. Hellwarth's new laser theory. How does it work? Current
Applications of Lasers Medical Communications Fiberoptics Commercial The National
Government Defense NASA Cancer Therapy Equipment Types of
Lasers Coming Soon Laser scalpal Apollo 11 placed reflectors on the moon LISA project Atmospheric conditions Absorption/Emission process Stimulated Emission Optical Pumping Absorption/Emission Process Energy of atom in ground state Energy of atom when in excited state How much energy is needed to excite the atom? Gas
Laser Helium-Neon Argon Carbon Dioxide Most common and inexpensive 632.8 nm 543.5 nm 1523 nm (infrared) capable of producing 10 kW of power electrical pumping Most efficient laser:
more than 30% efficiency industrial welding and cutting Capable of different wavelengths in visible range. Most efficient transitions occur in
488 nm - 514.5 nm It takes typically 9 - 12 kW of power for the laser to have 30 - 100 W of continuous power. Carbon Dioxide laser Solid-State
Laser LIDAR ruby laser "host" material Neodymium
Ytterbium Others Fiber
Free Electron How does an atom receive that specific energy? Absorption of a photon! Spontaneous Emission RANDOM
Emission Before Emission During Emission After Emission Atom is already in excited state. Population Inversion Remember when photons are emitted, they travel in a RANDOM direction. Photons continue with the absorption and emission processes. As photons keep getting re-emitted, they can travel through the walls of the laser cavity.
Maintain a population inversion. Optical Pumping More and more photons keep getting pumped into the cavity in order to excite the now ground state atoms. 1966 Alfred Kastler wins the Nobel Prize in physics
for his method of stimulating atoms to higher
energy levels. 1974 A pack of Wrigley's gum was the first item to be scanned by a barcode scanner. 2003 First successful flight of laser powered aircraft. 2010 The National Nuclear Security Administration delivered a 1 MJ laser. 500 times stronger than any laser at that time. How they work Electrical pumping. NOT optical Helium = pumping medium One of He excited states has energy of 20.61 eV. Ne excited has energy of 20.66 eV Spontaneous Emission does the rest of the work. Quantum computers Holography [AuroraMassShooting]. (2013, April 9th) US navy laser cannon shoots down drone from USS Ponce.
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National Aeronautics and Space Administration. 12/10/1996. Fact Sheets. Retrieved from http://www.nasa.gov/centers/langley/news/factsheets/LaserTech.html.
Nave, C. R. (2001). Lasers. Retrieved from http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
Pessina, L. A. (2013, February 20). A new light source for quantum computers. Phys Org. Retrieved from http://phys.org/news/2013-02-source-quantum.html
Petrou, A. Light Amplification by Stimulated Emission of Radiation [PDF document]. Retrieved from http://www.physics.buffalo.edu/faculty/APetrou/diffraction_of_light_intro.pdf
Rose, M. (2010). A History Of The Laser: A Trip Through The Light Fantastic. Photonics Spectra. Retrieved from http://www.photonics.com/Article.aspx?AID=42279.
Stewart, P. (2013, April 9th). U.S. Navy Deploys Laser That Shoots Down Drones. The Huffington Post. Retrieved from http://www.huffingtonpost.com/2013/04/09/navy-lasers-drones_n_3044177.html.