CONSTRAINTS OF GROUND-BASED OBSERVATIONS: THE ATMOSPHERE -- INTERFERENCES -- A BRIEF HISTORY OF ASTRONOMICAL TELESCOPES -- MODERN OPTICAL DESIGN -- STRUCTURAL MECHANICS -- SEGMENTED MIRROR TELESCOPES -- HECTOMETRIC OPTICAL TELESCOPES ESO'S 100-M OWL TELESCOPE CONCEPT -- OPTICAL FABRICATION FOR THE NEXT GENERATION OPTICAL TELESCOPES, TERRESTRIAL AND SPACE -- OPTICAL TESTING FOR THE NEXT GENERATI…