What optical device is the Dutch scientist, after whom the lunar crater Jansen is named, credited for?
Jansen (crater) Jansen is a lunar crater in the north part of the Mare Tranquillitatis, named after Zacharias Janssen. It is located to the east-southeast of the crater Plinius. The rim of Jansen is low and narrow, with a notch along the western edge. The interior is relatively level, which may indicate it has been covered by lava. To the south-southwest a small but prominent crater lies on the crater floor, halfway between the center and the rim, further southeast is a small but prominent crater named Sinas.
John Jacob Bausch Johan (John) Jacob Bausch (July 25, 1830 – February 14, 1926) was an American maker of optical instruments who co-founded Bausch & Lomb (with Henry Lomb). Over six decades he transformed his small, local optical shop into a large-scale international enterprise, pioneering the American optical industry.