Download - Dr. Mike Nofziger 2010 “LASERS” Light Amplification by the Stimulated Emission of Radiation
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Dr. Mike Nofziger 2010
“LASERS”Light Amplification by the Stimulated Emission of Radiation
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Dr. Mike Nofziger 2010
“LASERS” ….. small
Tunable Diode Laser- about 2mm x 2mm chip- used to measure water vapor concentration in the near-IR- used to detect low-levels of gas concentration (ppm, ppb)
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Dr. Mike Nofziger 2010
“LASERS” ….. Large!!!
NOVA Laser at LLNL
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Dr. Mike Nofziger 2010
“LASERS” ….. History1917--Albert Einstein describes the photon and points out that stimulated emission of light could occur.
1958--Arthur Schawlow and Charles Townes publish their theoretical paper "Infrared and Optical Masers" in Physical Review, 1958.
1960 --Theodore Maiman invents the first laser, the optical version of the maser, using a man-made ruby crystal. First operated on May 16, 1960.
1961--HeNe gas laser is invented by Ali Javan, et al., Bell Labs. -first laser to emit a continuous (CW) beam of light -first output was at 3.39 microns, in the infrared -visible output at 0.633 microns (633 nm) in 1962 -"workhorse of the laser industry“
1963--CO2 gas laser is invented by Patel, Bell Labs.1964--Argon ion laser is invented by Bridges, Hughes Research Labs.1966--Organic Dye (liquid) laser is invented.1970's--Semiconductor lasers are run at room temperature, paving the way for their practical use today.
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Dr. Mike Nofziger 2010
“LASERS” ….. 2010, the 50th Anniversary!
“A solution looking for a problem.”
http://spie.org/media/laserplayer/laserplayer.html
http://www.laserfest.org/
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Dr. Mike Nofziger 2010
“LASERS” ….. Basic Principle
Light Amplification by the Stimulated Emission of Radiation
Atoms absorb energy…
A population inversion is created…
The atoms return to their non-energetic states by emitting radiation(“light”--UV, visible, or IR) through stimulated emission…
Feedback in an optical cavity amplifies this light…
Some of this light is emitted in the form of laser light!
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Dr. Mike Nofziger 2010
“LASERS” ….. Stimulated Emission
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Dr. Mike Nofziger 2010
“LASERS” ….. Characteristics of Laser Light
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Dr. Mike Nofziger 2010
“LASERS”“LASERS” ….. Laser Speckle
(random interference pattern)
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Dr. Mike Nofziger 2010
"How to Make a Laser"
"Gain medium (to provide for population inversion)"+
"Input source of energy (electricity, light, etc.)"+
"Resonant cavity (provides optical feedback and sustains stimulated emission)"
“LASERS” ….. Fundamental Parts
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: The Ruby Laser
The RubyLaser
- Sapphire crystal doped with chromium ions (≈ 0.05%)
- The sapphire rod has flat, polished ends coated with gold
- The chromium ions absorb the input white-light and emit the laser light
- Wavelength of 694 nm (ruby-red color)
- Output beam is pulsed
- Needs high voltage to run the flash lamp
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: The Ruby Laser
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: The Ruby Laser
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: He-Ne Laser
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: He-Ne Laser
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: He-Ne Laser
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Dr. Mike Nofziger 2010
“LASERS”“LASERS” ….. Example: Red laser pointer
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Dr. Mike Nofziger 2010
“LASERS”
Red Laser Pointer- direct output of red light from the Laser Diode (“LD”)
λ = 633nm, 650nm, 670nm, etc.- output is monitored by the built-in photodiode detector (“PD”)- beam expands and is collimated by the aspheric lens
“LASERS” ….. Example: Red laser pointer
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Dr. Mike Nofziger 2010
5mW beam
λ = 532 nm
“LASERS” ….. Example: Green laser pointer
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Dr. Mike Nofziger 2010
“LASERS”
Diode-Pumped Solid State “DPSS laser”- 808nm (near-infrared) pump diode laser 808nm energy converted to 1064nm by the Nd:YVO4 crystal- 1064nm energy converted to 532nm green light by the KTP crystal
- this is a non-linear process called “frequency-doubling”- the input frequency is doubled, and the output wavelength is cut in half
- beam is expanded - beam is collimated- beam is filtered to block the (powerful) original IR energy at 808nm
“LASERS” ….. Example: Green laser pointer
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Dr. Mike Nofziger 2010
“LASERS” – Red vs. Green
Reference: “Sam’s Laser FAQ”
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Dr. Mike Nofziger 2010
λ = 405 nm “blue”P = 150 mW
λ = 532 nm “green”P=50mW
“LASERS” – Red, Green and now Blue!
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: High-Power Diodes
- Stacks of linear arrays of diode lasers- 100’s to kilowatts of power- near infrared wavelengths- used for materials processing
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Dr. Mike Nofziger 2010
“LASERS” ….. Example: CD Diode Lasers
output in the near-infrared≈ 5 – 50mW output actual laser chip from a CD player
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Dr. Mike Nofziger 2010
“LASERS”
Laser Guide Stars
- VLT 8.2m telescopes- creates an artificial star at an altitude of 90
km- yellow sodium line- part of the VLT’s Adaptive Optics system
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Dr. Mike Nofziger 2010
“LASERS”
http://en.wikipedia.org/wiki/File:Lasercutting-video.ogg
top: CAD modelbottom: laser-cut part
- 0.5mm thick stainless steel
Laser Cutting
http://en.wikipedia.org/wiki/File:Remote_Fibre_Laser_Welding_WMG_Warwick.ogg
Laser WeldingCO2, Nd:YAGE ≈ 1MW/cm2
f beam < .5mmcarbon steel, stainless steel,aluminum,titanium