Joseph Jackson Lister reduces spherical aberration (which produces imperfect images) by using several weak lenses together at certain distances to give good magnification without blurring the image.

Ernst Abbe writes a mathematical formula that correlates resolving power to the wavelength of light. Abbe’s formula makes it possible to calculate the theoretical maximum resolution of a microscope.
Example of Abbe equation

Ernst Ruska and Max Knoll design and build the first transmission electron microscope (TEM), based on an idea of Leo Szilard. The electron microscope depends on electrons, not light, to view an object. Modern TEMs can visualise objects as small as the diameter of an atom.

Frits Zernike develops phase contrast illumination, which allows the imaging of transparent samples. By using interference rather than absorption of light, transparent samples, such as cells, can be imaged without having to use staining techniques.

Ernst Ruska builds the first scanning electron microscope, which transmits a beam of electrons across the surface of a specimen.

Marvin Minsky patents the principle of confocal imaging. Using a scanning point of light, confocal microscopy gives slightly higher resolution than conventional light microscopy and makes it easier to view ‘virtual slices’ through a thick specimen.

Osamu Shimomura, Frank Johnson and Yo Saiga discover green fluorescent protein (GFP) in the jellyfish Aequorea victoria. GFP fluoresces bright green when exposed to blue light.

Godfrey Hounsfield and Allan Cormack develop the computerised axial tomography (CAT) scanner. With the help of a computer, the device combines many X-ray images to generate cross-sectional views as well as three-dimensional images of internal organs and structures.

John Venables and CJ Harland observe electron backscatter patterns (EBSP) in the scanning electron microscope. EBSP provide quantitative microstructural information about the crystallographic nature of metals, minerals, semiconductors and ceramics.

Thomas and Christoph Cremer develop the first practical confocal laser scanning microscope, which scans an object using a focused laser beam.

Gerd Binnig and Heinrich Rohrer invent the scanning tunnelling microscope (STM). The STM ‘sees’ by measuring interactions between atoms, rather than by using light or electrons. It can visualise individual atoms within materials.

The Nobel Prize in Physics is awarded jointly to Ernst Ruska (for his work on the electron microscope) and to Gerd Binnig and Heinrich Rohrer (for the scanning tunnelling microscope).

Douglas Prasher reports the cloning of GFP. This opens the way to widespread use of GFP and its derivatives as labels for fluorescence microscopy (particularly confocal laser scanning fluorescence microscopy).

Stefan Hell pioneers a new optical microscope technology that allows the capture of images with a higher resolution than was previously thought possible. This results in a wide array of high-resolution optical methodologies, collectively termed super-resolution microscopy.

Researchers at UCLA use a cryoelectron microscope to see the atoms of a virus.

Nobel Prize in Chemistry awarded to Eric Betzig, Stefan Hell and William Moerner for the development of super-resolved fluorescence microscopy which allows microscopes to now ‘see’ matter smaller than 0.2 micrometres.