While the exact invention of the light microscope is difficult to pinpoint, Zacharias Janssen is often credited with building the first compound microscope in the late 16th or early 17th century (around 1590-1600).

However, there is evidence suggesting that Hans Lippershey, a Dutch spectacle maker, had already applied for a patent for a similar device around the same time.

The invention of the microscope was a gradual process, with many individuals contributing to its development. It's important to note that:

* Cornelis Drebbel is also credited with building a compound microscope in the early 1600s.

* Galileo Galilei developed his own version of a compound microscope in 1610.

Therefore, while Zacharias Janssen is often attributed with the invention, the exact origins of the light microscope remain a bit unclear. It's more accurate to say that the invention was the result of a collective effort of several individuals during that period.