Lens innovation in the 17th-century Netherlands

Abstract
The telescope, invented in Middelburg in 1608, had a ground-breaking impact on our understanding of the universe. A catalyst for the Scientific Revolution, the instrument also introduced a broader engagement in optical ‘culture’ in the Golden-Age Netherlands. Nonetheless, the emergence and development of optical instrumentation faces historians of science with challenges. The telescope was there ‘before anyone knew’ but subsequently spread like a running fire, and revolutionized (mathematical) conceptualization about optics. How did this happen, and how does it correspond with technological changes in lens grinding?
Answering this question has for a long time been hindered by another curious fact: nearly none of the 17th-century Dutch optical instruments appear to have been preserved. In order to remedy this, Cocquyt developed a portable interferometer to analyze the optics of reference pieces in international collections, and to discover and shed new light on possible Dutch early lens candidates. Confronting these findings with unexplored lens grinding instructions from the 17th-century Netherlands allows him to sketch an interesting narrative of how optical technology and ‘culture’ developed in this period. Finally, it also allowed him to answer a long-standing question: did Christiaan Huygens really grind the best objective lenses in the world, as he stated in 1659, much to the dislike of his colleague telescope makers?