MICROANATOMY

Detailed explanation-1: -For most of the twentieth century, it was held that far-field light microscopy could not resolve objects closer than 150–200 nanometres (see Milestone 3). This is because light diffracts as it passes through different media, so that the light emanating from a point is detected as emerging from a larger volume.

Detailed explanation-2: -Because our eyes can only detect photons with wavelengths greater than  400 nm, the best resolution that can be achieved by light microscopes is about  200 nm. One way to beat the diffraction limit of light is to use an illumination source with a shorter wavelength than photons – electrons (see Box 1).