An early instrumentalist was Leonardo Da Vinci. One of his notebook pages on display this summer at the new British Library in London shows clear exercise in "Huyghens' Principle" of secondary wave sources. Here's a blurb from the Timeline in Optics web page:

"Da Vinci was also fascinated with the study of optics and did extensive studies and drawings about the nature of light, reflections and shadows. Even though it was not until over 100 years later that the first telescope was invented by Hans Lippershey, da Vinci realized the possibility of using lenses and mirrors to view heavenly bodies. In his notebooks he writes of:

...making glasses to see the Moon enlarged... and ...in order to observe the nature of the planets, open the roof and bring the image of a single planet onto the base of a concave mirror. The image of the planet reflected by the base will show the surface of the planet much magnified."