الفهرس 
General principles of laserOnly 14 pages are availabe for public view
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Abstract
Therapeutic retinal photocoagulation has been practiced over the past 30 yaers. In 1960, the first laser was constructed by maiman, using a ruby laser but ntil now and inspite of various types of laser , a satisfactory laser sourse emitting radiation is still lacking . Icons lasers suffer from several drawbacks due to their very low electrical to-optical effeciency which responsiple for the extremly high cost , during the past few years great progress have been achieved in technology of semiconductor diobe laser.