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Dr. Mike Nofziger 2010 LASERS Light Amplification by the Stimulated Emission of Radiation.

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Presentation on theme: "Dr. Mike Nofziger 2010 LASERS Light Amplification by the Stimulated Emission of Radiation."— Presentation transcript:

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

2 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)

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

4 Dr. Mike Nofziger 2010 LASERS ….. History Albert Einstein describes the photon and points out that stimulated emission of light could occur Arthur Schawlow and Charles Townes publish their theoretical paper "Infrared and Optical Masers" in Physical Review, Theodore Maiman invents the first laser, the optical version of the maser, using a man-made ruby crystal. First operated on May 16, 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 microns (633 nm) in "workhorse of the laser industry CO 2 gas laser is invented by Patel, Bell Labs Argon ion laser is invented by Bridges, Hughes Research Labs Organic Dye (liquid) laser is invented. 1970's--Semiconductor lasers are run at room temperature, paving the way for their practical use today.

5 Dr. Mike Nofziger 2010 LASERS … , the 50 th Anniversary! A solution looking for a problem.

6 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!

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

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

9 Dr. Mike Nofziger 2010 LASERSLASERS ….. Laser Speckle (random interference pattern)

10 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

11 Dr. Mike Nofziger 2010 LASERS ….. Example: He-Ne Laser The Helium-Neon (He-Ne) Laser - Output powers relatively low ( mW) - Wavelength of 633 nm (reddish-orange color) - Output beam is a very clean, TEM 00 Gaussian profile (can be focused to a very small spot) - Small diameter, long glass tube construction - Needs approx. 5-10kV to run (to make the plasma)

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

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

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

15 Dr. Mike Nofziger 2010 LASERSLASERS ….. Example: Red laser pointer

16 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

17 Dr. Mike Nofziger mW beam λ = 532 nm LASERS ….. Example: Green laser pointer

18 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:YVO 4 crystal nm 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

19 Dr. Mike Nofziger 2010 LASERS – Red vs. Green Reference: Sams Laser FAQSams Laser FAQ

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

21 Dr. Mike Nofziger 2010 LASERS ….. Example: High-Power Diodes - Stacks of linear arrays of diode lasers - 100s to kilowatts of power - near infrared wavelengths - used for materials processing

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

23 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 VLTs Adaptive Optics system

24 Dr. Mike Nofziger 2010 LASERS top: CAD model bottom: laser-cut part - 0.5mm thick stainless steel Laser Cutting Laser Welding CO 2, Nd:YAG E 1MW/cm 2 f beam <.5mm carbon steel, stainless steel, aluminum, titanium


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