Optical interferometry

Abstract

When Galileo first used a telescope for astronomical research in 1609 he gained two immediate advantages over his contemporaries. First, the objective lens of his telescope, which was about 2cm in diameter, collected more light than the unaided eye, which enabled him to look at fainter objects. Second, he could see much finer detail than was possible with even the best naked eye. In other words, the telescope allowed him to obtain much better angular resolution than was ever possible before.