What optical device is the Dutch scientist, after whom the lunar crater Jansen is named, credited for?
Zacharias Janssen Zacharias Janssen (also Zacharias Jansen or Sacharias Jansen) (1585 – pre-1632) was a Dutch spectacle-maker from Middelburg associated with the invention of the first optical telescope. Janssen is sometimes also credited for inventing the first truly compound microscope. However, the origin of the microscope, just like the origin of the telescope, is a matter of debate.
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.