ABSTRACT
Applications ................................................................................................. 61 1.4.7.5 LED Applications in Medicine and Dentistry ............................................. 62 1.4.7.6 LED Applications in Horticulture, Agriculture, Forestry, and Fishery ...... 63 1.5 Lasers ......................................................................................................................................64 1.5.1 Stimulated Emission and Light Amplifi cation .............................................................65 1.5.2 Essential Elements of a Laser ...................................................................................... 67
1.5.2.1 Gain Medium ............................................................................................... 67 1.5.2.2 Pump ............................................................................................................68 1.5.2.3 Laser Cavity .................................................................................................69 1.5.2.4 Cooling System ............................................................................................ 70 1.5.3 Operating Characteristics of a Laser ........................................................................... 70 1.5.3.1 Laser Modes ................................................................................................ 70 1.5.3.2 Gaussian Laser Beams ................................................................................ 72 1.5.3.3 Continuous Wave and Pulsed Operation ..................................................... 73 1.5.4 Characteristics of Laser Light ...................................................................................... 73 1.5.4.1 Monochromaticity ....................................................................................... 73 1.5.4.2 Coherence .................................................................................................... 74 1.5.4.3 Divergence ................................................................................................... 76 1.5.4.4 Focusing a Laser Beam ...............................................................................77 1.5.4.5 Laser Irradiance...........................................................................................77 1.5.5 Laser Systems...............................................................................................................77 1.5.5.1 Gas Active Medium .....................................................................................77 1.5.5.2 Liquid Active Medium ................................................................................ 78 1.5.5.3 Solid-State Active Medium ......................................................................... 78 1.5.5.4 Semiconductor Active Medium ................................................................... 78 References ........................................................................................................................................ 79 Web Sites ..........................................................................................................................................84
