Zernike phase contrast method

F. Zernike (Groningen) demonstration of the phase contrast method and invention of the phase contrast microscope. 

In the optical microscope the Zernike phase contrast method is applied to convert the phase modulation into a contrast, by adding a phase plate in the back focal plane. This is very close to the wave aberration at the Scherzer focus, but the performance of the electron microscope is rather limited. Even the minimum Cs available today does not allow a carbon atom to be visualized. The solution is to add a new spherical corrected objective lens for sub-angstrom resolution. Figure 13 shows the optical path of a beam in a TEM working under holographic conditions. 

Zernike F 1942 Phase contrast, a new method for the microscopic observation of transparent objects I Physica 9 686... 

Zernike F (1942) Phase contrast a new method for the observation of transparent objects. Physica 9 686-693... 

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