LI Flashes of brilliance developed long before its applications years ago Arthur Schawlow and Charles A splendid light has dawned on me he widespread applications it would have in a variety dustries. The impact of this invention is usually not In 1917 Einstein published ideas on stimulated emission of radiation. These ideas laid the basic foundation for the ating w futuristic idea depicted in Hollywood me Most people don't recognize that laser is now known as the photoelectric effect, Einstein noted a echnology is already present as an integral part of our statistical tendency which caused photons(particles of daily lives allowing us to listen to cds. watch dvd's. and er. In additio lay computer games. Additionally, lasers are becoming creasingly visible in medicine in ophthalmologic, hotons stimulated other atoms to emit more photons cosmetic, and general surgery. Einstein was also able to prove that these emitted photons all traveled in the same direction and with the same frequency as the original photon. Flashes of brilliance Lasers eOne important application of semiconductor devices is in lasers which are intense sources of 品 invented in 1958 by Charles H ingle frequency electromagnetic radiation and Arthur L rs exploit an important process known as stimulated emission in which the emission of AL Schawlow erm"laser with help from his CH Tow a photon at a given frequency stimulates the differentiating factor between emission of other photons at the same the two devices is that th frequency aser uses light waves as o an important property of stimulated opposed to the microwave emission is that the resulting photons emitted utilized by the maser. in this process form a highly coherent bea Laser= Einstein Right type+ Reflecting An example of stimulated emission Ruby laser tion between two levels in an atom The ruby laser is the first type of laser actu onstructed. first demonstrated in 1960 by T H. Maiman actly the energy difference of the two levels stimulates the electron in caracteristic pink or red color by absorbing green and blue the higher energy state to undergo a ruby laser is used as a pulsed laser, producing red energy, twe Aft otons are emitted in this process flash tube, the laser light emerge the excited and these photons are highly atoms persist in the ruby rod, whicl the photons may be used to induce stimulated emission between the e two levels5 The laser is an example of a technology that was developed long before its applications were ever imagined. Forty-five years ago Arthur Schawlow and Charles Townes could have had no possible way of knowing the profound effects this technology would have on society or the widespread applications it would have in a variety of industries. The impact of this invention is usually not realized because many consider laser technology a futuristic idea depicted in Hollywood movies or science fiction books. Most people don’t recognize that laser technology is already present as an integral part of our daily lives, allowing us to listen to CD’s, watch DVD’s, and play computer games. Additionally, lasers are becoming increasingly visible in medicine in ophthalmologic, cosmetic, and general surgery. Flashes of Brilliance The History of the Laser “A splendid light has dawned on me” –Albert Einstein In 1917 Einstein published ideas on stimulated emission of radiation. These ideas laid the basic foundation for the invention of the laser years later. While investigating what is now known as the photo-electric effect, Einstein noted a statistical tendency which caused photons (particles of light), to want to move together. In addition, emitted photons displayed a sort of snowball effect, once emitted, photons stimulated other atoms to emit more photons. Einstein was also able to prove that these emitted photons all traveled in the same direction and with the same frequency as the original photon. Flashes of Brilliance From Maser to Laser AL Schawlow CH Townes The laser is credited as being invented in 1958 by Charles H. Townes and Arthur L. Schawlow. Townes coined the term “laser”with help from his students. The main differentiating factor between the two devices is that the laser uses light waves as opposed to the microwaves utilized by the maser. Laser = + + Einstein’s Theories Right type of atoms Reflecting Mirrors One important application of semiconductor devices is in lasers which are intense sources of single frequency electromagnetic radiation * lasers exploit an important process known as stimulated emission in which the emission of a photon at a given frequency stimulates the emission of other photons at the same frequency Þ an important property of stimulated emission is that the resulting photons emitted in this process form a highly coherent beam Lasers An example of stimulated emission in an electronic transition between two levels in an atom a photon whose energy matches exactly the energy difference of the two levels stimulates the electron in the higher energy state to undergo a transition to the lower energy state in order to conserve energy, two photons are emitted in this process and these photons are highly coherent the photons may be used to induce stimulated emission between the same two levels in other atoms giving rise to an avalanche effect PHOTON PHOTON PHOTON Ruby Laser The ruby laser is the first type of laser actually constructed, first demonstrated in 1960 by T. H. Maiman. The ruby mineral (corundum) is aluminum oxide with a small amount(about 0.05%) of chromium which gives it its characteristic pink or red color by absorbing green and blue light. The ruby laser is used as a pulsed laser, producing red light at 694.3 nm. After receiving a pumping flash from the flash tube, the laser light emerges for as long as the excited atoms persist in the ruby rod, which is typically about a millisecond