Editing Optical microscope (section)

===Lighting techniques===
While basic microscope technology and optics have been available for over 400 years it is much more recently that techniques in sample illumination were developed to generate the high quality images seen today.{{Citation needed|date=August 2024}}

In August 1893, [[August Köhler]] developed [[Köhler illumination]]. This method of sample illumination gives rise to extremely even lighting and overcomes many limitations of older techniques of sample illumination. Before development of Köhler illumination the image of the light source, for example a [[lightbulb]] filament, was always visible in the image of the sample.{{Citation needed|date=August 2024}}

The [[Nobel Prize]] in physics was awarded to Dutch physicist [[Frits Zernike]] in 1953 for his development of [[phase contrast]] illumination which allows imaging of transparent samples. By using [[Interference (wave propagation)|interference]] rather than [[Absorption (electromagnetic radiation)|absorption]] of light, extremely transparent samples, such as live [[mammalian]] cells, can be imaged without having to use staining techniques. Just two years later, in 1955, [[Georges Nomarski]] published the theory for [[differential interference contrast]] microscopy, another [[Interference (wave propagation)|interference]]-based imaging technique.{{Citation needed|date=August 2024}}