TELESCOPES OF GALILEO

The Florentine Istituto e Museo di Storia della Scienza houses two com plete telescopes and a single objective lens (reconstructed from sever al fragments) that can be attributed to Galileo. These optics have bee n partially dismantled and made available for optical testing with sta te-of-the-art equipment. The lenses were investigated individually; th e focal length and the radii of curvature were measured, and the optic al layout of the instruments was worked out. The optical quality of th e surfaces and the overall performance of the two complete telescopes have been evaluated interferometrically at a wavelength of 633 nm (wit h a He-Ne laser source). It was found in particular that the optics of Galileo came close to attaining diffraction-limited operation.