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“LASERS ”

“LASERS ”. L ight A mplification by the S timulated E mission of R adiation. “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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“LASERS ”

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  1. “LASERS” • Light Amplification by the Stimulated Emission of Radiation Dr. Mike Nofziger 2010

  2. “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) Dr. Mike Nofziger 2010

  3. “LASERS” ….. Large!!! • NOVA Laser at LLNL Dr. Mike Nofziger 2010

  4. “LASERS” ….. History 1917--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. Dr. Mike Nofziger 2010

  5. “LASERS” ….. 2010, the 50th Anniversary! • “A solution looking for a problem.” http://spie.org/media/laserplayer/laserplayer.html http://www.laserfest.org/ Dr. Mike Nofziger 2010

  6. “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! Dr. Mike Nofziger 2010

  7. “LASERS” ….. Stimulated Emission Dr. Mike Nofziger 2010

  8. “LASERS” ….. Characteristics of Laser Light Dr. Mike Nofziger 2010

  9. “LASERS” • “LASERS” ….. Laser Speckle • (random interference pattern) Dr. Mike Nofziger 2010

  10. “LASERS” ….. Fundamental Parts Dr. Mike Nofziger 2010

  11. “LASERS” ….. Example: He-Ne Laser Dr. Mike Nofziger 2010

  12. “LASERS” ….. Example: He-Ne Laser Dr. Mike Nofziger 2010

  13. “LASERS” ….. Example: He-Ne Laser Dr. Mike Nofziger 2010

  14. “LASERS” ….. Example: He-Ne Laser Dr. Mike Nofziger 2010

  15. “LASERS” • “LASERS” ….. Example: Red laser pointer Dr. Mike Nofziger 2010

  16. “LASERS” • “LASERS” ….. Example: Red laser pointer • 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 Dr. Mike Nofziger 2010

  17. “LASERS” ….. Example: Green laser pointer • λ= 532 nm • 5mW beam Dr. Mike Nofziger 2010

  18. “LASERS” • “LASERS” ….. Example: Green laser pointer • 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 Dr. Mike Nofziger 2010

  19. “LASERS” – Red vs.Green • Reference: “Sam’s Laser FAQ” Dr. Mike Nofziger 2010

  20. “LASERS” – Red, Green and now Blue! • λ= 405 nm • “blue” • P = 150 mW • λ= 532 nm • “green” • P=50mW Dr. Mike Nofziger 2010

  21. “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 Dr. Mike Nofziger 2010

  22. “LASERS” ….. Example: CD Diode Lasers • output in the near-infrared • ≈ 5 – 50mW output • actual laser chip from a CD player Dr. Mike Nofziger 2010

  23. “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 Dr. Mike Nofziger 2010

  24. “LASERS” • Laser Cutting http://en.wikipedia.org/wiki/File:Lasercutting-video.ogg • Laser Welding • CO2, Nd:YAG • E ≈ 1MW/cm2 • beam < .5mm • carbon steel, stainless steel, • aluminum, • titanium http://en.wikipedia.org/wiki/File:Remote_Fibre_Laser_Welding_WMG_Warwick.ogg • top: CAD model • bottom: laser-cut part • 0.5mm thick stainless steel Dr. Mike Nofziger 2010

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