10. Laser Beam Welding kau.ac.kr（10。）.pdfVIP

10. Laser Beam Welding 10. Laser Beam Welding 134 The term laser is the abbreviation for ,,Light Amplification by Stimulated Emission of Radia- tion”. The laser is the further development of the maser (m=microwave), Figure 10.1. Al- though the principle of the stimulated emis- 1917 postulate of stimulated emission by Einstein sion and the quantum-mechanical fundamen- 1950 work out of physical basics and realisation of a tals have already been postulated by Einstein maser (Microwave Amplification by Stimulated Emission of Radiation) by Towens, Prokhorov, Basov 1954 construction of the first maser in the beginning of the 20th century, the first 1960 construction of the first ruby laser (Light Amplification laser - a ruby laser - was not implemented by Stimulated Emission of Radiation) 1961 manufacturing of the first HeNe lasers and Nd: glass lasers until 1960 in the Hughes Research Laborato- 1962 development of the first semiconductor lasers ries. Until then numerous tests on materials 1964 nobel price for Towens, Prokhorov and Basov for their had to be carried out in order to gain a more works in the field of masers construction of the first Nd:YAG solid state lasers and CO gas lasers precise knowledge about the atomic structure. 2 1966 established laser emission on orga