![]() Torricelli, Divini, and Campani were some of the best optics makers of Galileo’s day. Note that lamda/4 optics are diffraction-limited, and Galileo’s optics achieve this (for a single wavelength, they still have chromatic aberration). This is a slide of mine, showing how different quality metrics compare. It looks like less than a quarter wavelength of aberration, peak-to-valley. Here are some more fringe patterns from Galileo’s telescopes, from this publication. These fringe patterns are not that bad, especially for lenses that are over 300 years old. Giuseppe Molesini and his Italian colleagues have studied these artifacts with modern interferometry and found them to be quite exquisite. ![]() Some of Galileo’s telescopes survive to this day, as part of the Medici collection. Galileo’s telescopes revealed new details about the wandering stars, and his findings kicked off a new phase in the development of optics. He lived in Pisa, not far from the best glass makers in Europe, who were– in that same moment– perfecting techniques for making high quality clear glass, and cutting and polishing precision lenses. Best of all, he was in the right place at the right time. He knew the basic physics and math and figured out how it probably worked. Galileo was dialed into the scientific network of the day to hear rapidly about the Dutch invention of a telescope device. With feedback –be it quantitative measurements from instruments or qualitative judgements of image quality– this active alignment process can rapidly converge on excellent optics, as it did for Galileo. Careful application of these tools can provide enough degrees of freedom to recover excellent performance, often diffraction-limited performance, even when the optics are imperfect. ![]() We do the same thing with our optics, designing in correction collars, adjustable air gaps, and even deformable mirrors. A point I want to make in this post, is that part of the high performance of Galileo’s telescopes was obtained through careful final adjustments. In my optics classes, I often give a brief historical account of Galileo’s telescopes. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |