Optical telescope
The telescope is more a discovery of optical craftsmen than an invention of a scientist. The lens and the properties of refracting and reflecting light had been known since antiquity and theory on how they worked were developed by ancient Greek philosophers, preserved and expanded on in the medieval Islamic world, and had reached a significantly advanced state by the time of the telescope's invention in early modern Europe. But the most significant step cited in the invention of the telescope was the development of lens manufacture for spectacles, first in Venice and Florence in the thirteenth century, and later in the spectacle making centers in both the Netherlands and Germany. It is in the Netherlands in 1608 where the first recorded optical telescopes (refracting telescopes) appeared. The invention is credited to the spectacle makers Hans Lippershey and Zacharias Janssen in Middelburg, and the instrument-maker and optician Jacob Metius of Alkmaar.
Cornelis Drebbel
One of the optical devices some historians believe Drebbel invented when he was working for the Duke of Buckingham was the compound microscope. The device appeared in Europe around 1620 with the earliest account being Dutch Ambassador Willem Boreel's 1619 visit to London where he saw a compound microscope in Drebbel's possession, described as an instrument about eighteen inches long, two inches in diameter, and supported on 3 brass dolphins. In 1621 Drebbel had a compound microscope with two convex lenses. Several of his contemporaries, including Christiaan Huygens, credited the invention of the compound microscope to Drebbel. The invention has many counter claims including Dutch spectacle-maker Johannes Zachariassen's claim that Drebbel stole the idea from him and his father, Zacharias Jansen, and claims that Galileo Galilei used his telescope after 1610 as a type of compound microscope. In 1624 Galileo saw Drebbel's design for a microscope in Rome and created an improved version of it to send to Federico Cesi, founder of the Accademia dei Lincei, who used it to illustrate "Apiarum", his book about bees.