Demonstrations

Laser Theory

Code Number :	9B62.10
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: University of Iowa Disclaimer All Rights Reserved..
Condition :	Good
Principle :	Atomic Excitation and Emission
Area of Study :	Modern Physics, Lasers
Equipment :	Laser Demo with Ping-Pong Balls, Strobe Light with Pickup Processor Box and Photocell Counter, Ringstand, Airhose.
Procedure :	The large metal demo with the ping-pong balls is an example taken right out of McCliments book, Page 780, Figure 23-34. Everything should be explained there. Stick the photogate into the hole in the back of the demo pointing towards the black screen on the Plexiglas front. Turn on the strobe. Start the air blowing first - Full blast out of the compressed air line - and then open the gate to let the balls into the stream. There should be a population inversion at the top layer and as the ping-pong balls fall from this level to the next level they should trigger the photocell which will flash the strobe. (This is the spontaneous emission.) The balls have to be falling at a rate faster than 200 balls per minute for the strobe to work properly. Close the gate that lets the balls into the air stream BEFORE you shut off the air stream. Note: This is a very NOISY demo so do your explanations before or afterwards.

References

David V. Guerra, "The Human Laser", TPT, Vol. 34, # 3, Mar. 1996, p. 170.

David A. Van Baak, "Just How Bright Is A Laser?", TPT, Vol. 33, # 8, Nov. 1995, p. 497.

Claudine Carlton, "Lasers", TPT, Vol. 30, # 8, Nov. 1992, p. 486.

"What's a Laser?", TPT, Vol. 24 (1), Jan, 1986, A Physics Student Newsletter, Vol. I, # 1, Jan. 1986.

Phillip F. Schewe, "Laser", TPT, Vol. 19, # 8, Nov. 1981, p. 534.

John F. Ready, "Properties and Applications of Lasers", TPT, Vol. 6, # 7, Oct. 1968, p. 344.

C. L. Strong, "The Amateur Scientist", Scientific American, Vol. 224, # 7 to 12, 1971, p. 218.

William E. Carter, Ramesh L. Shrestha and K. Clint Slatton, "Geodetic Laser Scanning", Physics Today, Dec. 2007, p. 41.

Mark Wilson, "Researchers Achieve Lasing From a Single Trapped Atom," Physics Today, Jan. 2004, p. 16.

John H. Moore, Christopher C. Davis, Michael A. Coplan, "Lasers," Building Scientific Apparatus 2^nd Edition, pp. 206-228.

Gordon McComb, "He-Ne Colors," Lasers, Ray Guns, & Light Cannons, pp. 70-71.

Edward R. McCliment, Physics, pp. 780, Figure 23-24.

T. D. Rossing, C. J. Chiaverina," # 6.7, Laser Light", Light Science, Physics and Visual Arts, p. 137.

T. D. Rossing, C. J. Chiaverina, "Figure 6.6, Transitions Between Energy Levels in Ruby Laser", Light Science, Physics and Visual Arts, p. 139.

Mail Questions and Comments to: Dale Stille