Which device earned Fritz Zernike the 1953 Nobel Prize in Physics?

The phase-contrast microscope earned Fritz Zernike the 1953 Nobel Prize in Physics.

Zernike developed phase-contrast microscopy to make transparent structures visible without staining them. Many biological specimens alter the phase of light passing through them but absorb very little light, so they can appear nearly invisible in ordinary bright-field microscopy. His optical system converts phase differences into differences in brightness.

The method became especially valuable in biology and medicine because living cells could be observed with less damage and without dyes. It made details such as cell boundaries, nuclei, and internal movement easier to study. Zernike’s work grew from his broader research in optics and diffraction.

The prize citation recognized his demonstration of the phase-contrast method and invention of the phase-contrast microscope. It is not the same technology as electron microscopy, which uses beams of electrons rather than visible light.