50 Fun Facts About Microscopes

What is a microscope used to examine?

Objects too small to see with the naked eye are the microscope's subject; the earliest and most common type, the optical microscope, uses glass lenses to magnify them with visible light.

Around what year did the earliest known compound microscopes appear in Europe?

Around 1620 the earliest known compound microscopes appeared in Europe; the inventor is unknown, with rival claims centred on spectacle-makers in the Netherlands.

Which Dutch spectacle-maker is claimed, by his own son, to have invented the compound microscope in 1590?

Zacharias Janssen's son Johannes made the 1590 claim in 1655, some twenty years after his father's death; Janssen, a spectacle-maker, was also twice accused of counterfeiting coins.

Which Dutch town housed, as neighbours, the spectacle-makers credited with the microscope and telescope?

Middelburg, in Zeeland, was home to both the family that claimed the microscope and their neighbour who lodged the first telescope patent application in 1608, the other claimant to the microscope.

What name did Galileo give to the compound microscope he built, before 'microscopio' was coined?

Occhiolino ('little eye') was Galileo's name for his instrument; Giovanni Faber coined 'microscopio' in a 1625 letter to Federico Cesi after Galileo presented it to the Accademia dei Lincei.

Whose 1665 book Micrographia had a huge impact largely because of its impressive illustrations?

Robert Hooke published Micrographia in January 1665; its detailed copperplate engravings of insects and plant matter, drawn from his own observations, drew wide attention and made it an early scientific best-seller.

Which biological term did Micrographia originate?

Cell was coined in Micrographia: the structure its author saw in a thin sliver of cork reminded him of the small rooms, or cells, of a monastery.

The largest fold-out plate in Micrographia, four times the size of the book, depicts what?

A louse clinging to a human hair fills the largest plate, which folds out to about four times the book's size; Samuel Pepys called Micrographia 'the most ingenious book that ever I read in my life'.

Micrographia was the first major publication of which institution?

The Royal Society, chartered in 1662, licensed Micrographia as its first major publication in 1665; the book became the first scientific best-seller and stirred wide public interest in microscopy.

Which illumination technique blocks the direct beam so only specimen-scattered light reaches the objective?

Dark-field illumination uses a central stop in the condenser to block the direct beam, so only light scattered by the specimen enters the objective and transparent objects glow against a black background.

What did van Leeuwenhoek report to London's scientific society on 9 October 1676?

The discovery of micro-organisms: his letter of 9 October 1676 described 'animalcules' swimming in rainwater and pepper infusions, and he later found them in scrapings from his own teeth.

How was van Leeuwenhoek's microscope constructed?

A tiny glass ball lens held between two riveted metal plates: a screw-adjusted needle held the specimen before the lens, and the surviving examples magnify up to about 275 times.

In what language did van Leeuwenhoek write all of his roughly 190 letters to London's scientific society?

Colloquial Dutch was the only language he commanded; he knew no Latin, so the society had his roughly 190 letters translated into English or Latin for its Philosophical Transactions.

Roughly how many lenses did van Leeuwenhoek grind during his lifetime?

More than 500 lenses were ground by van Leeuwenhoek over his lifetime, along with at least 25 single-lens microscopes, yet he kept his grinding methods secret.

Which Delft painter, baptised four days before him, had van Leeuwenhoek as the executor of his will?

Johannes Vermeer, baptised in Delft on 31 October 1632, four days before van Leeuwenhoek, died insolvent in 1675, and the microscopist was appointed to administer his estate; some suggest he posed for The Astronomer and The Geographer.

Which visiting monarch did van Leeuwenhoek show an 'eel-viewer' for blood circulation at Delft?

Peter the Great, touring western Europe with his Grand Embassy, had his boat moored near Delft and had van Leeuwenhoek brought aboard to show him blood circulating in an eel's tail.

Which Italian 'father of histology' began his microscopic studies with the lungs in the 1660s?

Marcello Malpighi saw capillaries in the lungs of frogs in 1661, completing the blood circuit William Harvey had predicted, and went on to found microscopic anatomy.

Who wrote The Fly's Eye (1644), the first detailed microscopic account of organic tissue?

Giambattista Odierna, a Sicilian priest and astronomer, published L'occhio della mosca in 1644, the first detailed microscopic study of organic tissue; the microscope remained largely a novelty until the 1660s.

On a compound microscope, what is the upper lens the viewer looks through called?

The eyepiece, also called the ocular, sits at the top of the tube and typically magnifies the objective's image a further 10 times for the viewer.

A 10x ocular combined with a 100x objective gives what total magnification?

Total magnification is the product of the two; oil immersion or ultraviolet light is needed to resolve detail beyond that.

Diffraction limits ordinary light microscopes to roughly what resolving distance?

200 nanometres, about half the wavelength of blue-green light, is the diffraction limit for an ordinary light microscope; magnification beyond that point is 'empty', revealing no more detail.

What is placed between objective and cover slip to push numerical aperture as high as 1.6?

Immersion oil, with a refractive index near 1.5 matching the glass, lets the objective gather light at wider angles, pushing numerical aperture as high as 1.6; such objectives usually magnify 40 to 100 times.

Which German optical engineer, partner of Carl Zeiss, was the first to define 'numerical aperture'?

Ernst Abbe, who became Carl Zeiss's partner, defined numerical aperture (n sin θ) in the 1870s, and in 1900 introduced the eight-hour working day at Zeiss in memory of his father's 14-hour days.

Who developed the 1893 microscope illumination method that keeps the lamp filament out of the image?

August Köhler published the method in 1893: focusing an image of the lamp at the condenser aperture rather than the specimen plane gives even lighting with no filament visible, and Köhler illumination became standard practice.

Which Dutch physicist won the 1953 Nobel Prize in Physics for inventing phase-contrast illumination?

Frits Zernike, at Groningen, devised phase-contrast illumination in the 1930s; it turns invisible phase shifts in transparent samples such as live cells into visible contrast without staining, and won him the 1953 Nobel Prize in Physics.

Who patented the principle of the confocal microscope in 1957?

Marvin Minsky, better known as an AI pioneer, filed the confocal patent in 1957 while a Harvard junior fellow; the lasers needed to make it practical came later, with a laser-scanning version in 1978.

Which fluorescent stain is commonly used to label DNA in cells?

DAPI (4',6-diamidino-2-phenylindole) binds strongly to A-T-rich regions of DNA and fluoresces blue under ultraviolet excitation, making it the standard nuclear counterstain; GFP and tagged antibodies label proteins instead.

Which German physicist, with engineer Max Knoll, built the first prototype electron microscope in 1931?

Ernst Ruska, working with Max Knoll at the Berlin Technical University, built the first electron microscope prototype in 1931 and shared a Nobel Prize in Physics more than half a century later.

What does an electron microscope use in place of the glass lenses of a light microscope?

Electromagnets serve as lenses: a current-carrying coil focuses a beam of electrons the way glass bends light, a principle Hans Busch demonstrated in 1926 and the 1931 Berlin prototype put to use.

Roughly what resolution can electron microscopes achieve?

0.1 nm, roughly the spacing of atoms, is reached by modern transmission electron microscopes, because an electron accelerated to 100 kV has a wavelength of about 4 picometres, over 100,000 times shorter than visible light.

Why must samples in an electron microscope usually be viewed in a vacuum?

Air molecules would scatter the electrons before they reached the sample or detector, so the column is pumped to high vacuum; environmental scanning electron microscopes are the exception, tolerating a little gas around hydrated samples.

Which company produced the first commercial transmission electron microscope, in 1939?

Siemens delivered the first commercial transmission electron microscope, the 'Übermikroskop', in 1939 from its Berlin works, where a physician was employed to develop biological applications for it.

Who pioneered the scanning electron microscope in 1937?

Manfred von Ardenne built the first true scanning electron microscope in his Berlin laboratory in 1937, rastering a focused beam across the specimen; a commercial instrument did not follow until 1965.

What was the first commercial scanning electron microscope, marketed in 1965, called?

Stereoscan was the name Cambridge Instrument Company gave the instrument, developed from Charles Oatley's Cambridge group with his student Gary Stewart; the first unit went to DuPont in 1965.

Which two IBM Zürich researchers invented the scanning tunneling microscope in 1981?

Gerd Binnig and Heinrich Rohrer built the first scanning tunneling microscope at IBM's Zürich laboratory in Rüschlikon in 1981, and soon after imaged the silicon (111) 7x7 surface reconstruction atom by atom.

A scanning tunneling microscope senses a surface using what?

An extremely sharp conducting tip is scanned a few atomic diameters above the surface; electrons tunnel across the gap, and the tunnelling current maps individual atoms.

IBM researchers used a scanning tunneling microscope to move atoms of which element on nickel?

Xenon atoms, 35 of them, were nudged across a nickel surface by Don Eigler and Erhard Schweizer at IBM Almaden in 1989-90 to spell 'IBM'; the same trick later built 'quantum corrals' of iron atoms on copper.

Who was the third author of the paper that introduced the atomic force microscope?

Christoph Gerber, an IBM Zürich engineer, was third author of the paper that introduced the atomic force microscope, which replaced the STM's tunnelling current with a force-sensing probe; true atomic resolution in liquid followed in 1993.

In an atomic force microscope, the sharp tip is fixed to the free end of what?

A small spring-like cantilever carries the tip at its free end; a laser reflected off the cantilever's back onto a photodiode records its deflection as the tip is scanned across the surface.

Which three scientists shared the 2014 Chemistry Nobel for super-resolved microscopy?

Eric Betzig, William Moerner and Stefan Hell shared the 2014 Nobel Prize in Chemistry for super-resolved fluorescence microscopy, which the citation said brought optical microscopy 'into the nanodimension'.

What does the super-resolution technique STED stand for?

Stimulated emission depletion uses a second, doughnut-shaped laser beam to switch off fluorescence around the focal spot, shrinking the emitting region far below the diffraction limit; the method was proposed in 1994.

Who filed the first telescope patent in 1608 and is sometimes credited with the microscope?

Hans Lippershey applied to the States General for a telescope patent in October 1608 (refused, as the design was too easy to copy) and is sometimes credited with the compound microscope as well.

Which Dutch inventor's 1624 Rome microscope prompted Galileo to build an improved one?

Cornelis Drebbel, the Alkmaar-born inventor, had been showing a two-lens microscope in London as early as 1619; a Drebbel instrument seen in Rome in 1624 spurred Galileo to produce his own improved version.

What did the author of Micrographia observe in cork bark that led him to coin his famous term?

Tiny walled compartments in a thin slice of cork reminded him of the small rooms of a monastery, and the 1665 book records the observation alongside studies of insects' eyes, fossils and the nature of light.

In which year did the scanning tunneling microscope's inventors win the Physics Nobel?

1986 is right: the Physics Nobel went to the STM's two inventors just five years after they built it at IBM Zürich, an unusually fast turnaround; the other half went to the electron microscope's pioneer.

How was the very first scanning tunneling microscope isolated from vibration?

Magnetic levitation on a superconducting lead bowl isolated the first STM at IBM Zürich from vibration, since the tunnelling current is exquisitely sensitive to tip-sample distance; later instruments used springs and eddy-current damping.

In which year did an electron microscope first exceed the resolving power of light microscopes?

1933 was the year the Berlin electron microscope surpassed the resolution of any light microscope, two years after the 1931 prototype; a commercial instrument followed at the end of the decade.

Where did Eli Franklin Burton and his students build an early North American electron microscope?

Toronto is right: at the University of Toronto in 1938 Eli Franklin Burton's students Cecil Hall, James Hillier and Albert Prebus built a working electron microscope; an earlier machine had been built at Washington State in 1935.

Who introduced the scanning transmission electron microscope with a field emission source?

Albert Crewe, at the University of Chicago, fitted a scanning transmission electron microscope with a cold field-emission gun in the late 1960s, and by 1970 his instrument imaged single heavy atoms.

The earliest known use of simple microscopes dates to the spread of what in the 13th century?

Eyeglasses, which spread through Italy from the 1280s, brought the lens-grinding trade that produced the first magnifying glasses; lens-like objects go back some 4,000 years and Greek writers described water-filled spheres.