Answer:
Frits Zernike
Explanation:
The easiest and most common way to image biological samples is using phase contrast, which is a special contrast-enhancing imaging method for transmitted-light microscopes invented by Frits Zernike (1888-1966) in 1932 [1] and introduced into microscopic practice by August Köhler (1866-1948) and Loos in 1941 [2, 3].
