100 Fun Facts About Microscopes

Vermont farmer Wilson Bentley attached a camera to his microscope in 1885 to photograph what?

Snowflakes: after photographing crystal after crystal before it could melt, Bentley argued that no two snow crystals are alike, an idea that caught the public imagination.

Robert Brown saw pollen particles jiggling in water under his microscope; who explained the motion in 1905?

Albert Einstein showed the particles were being jostled by individual water molecules, and his explanation became convincing evidence that atoms and molecules exist.

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

Zacharias Janssen's son made the claim in 1655, about twenty years after his father's death, and historians suspect the story may have been invented.

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

Middelburg, capital of Zeeland, housed both rival spectacle-making households, yet their claims were never settled and the microscope's true inventor is still unknown.

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

Occhiolino ('little eye') was Galileo's name for the instrument he sent Prince Federico Cesi in 1624; a year later fellow Lincean Giovanni Faber coined the word 'microscope'.

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

Robert Hooke also studied petrified wood under his microscope, and argued that fossils were the remains of once-living things.

Which biological term did Micrographia originate?

Cell was coined in Micrographia: its author found a thin slice of cork 'all perforated and porous, much like a Honey-comb', and called those pores cells.

Besides its famous flea, which parasite did Micrographia's author also draw?

A louse gets an engraving of its own, and the text jokes that it will never be quiet till it has drawn blood.

Micrographia was the first major publication of which institution?

The Royal Society ordered the book printed, yet it was often too short of money to pay its author his salary.

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

Dark-field illumination makes unstained, transparent specimens shine bright on a black background, which is why it suits live, water-borne microbes that have not been dyed.

What did van Leeuwenhoek describe in his letter of 9 October 1676?

The discovery of micro-organisms: his letter of 9 October 1676 described tiny 'animalcules' in water, and he later found them swarming in the plaque between his own teeth.

How was van Leeuwenhoek's microscope built?

A tiny lens set in a metal plate: the user held it right up to the eye while screws moved the specimen, pinned on a point, into focus.

What was van Leeuwenhoek's trade in Delft, long before his microscope letters made him famous?

Cloth merchant: he kept a draper's shop and held minor city posts, yet he made his own lenses by hand, more than 500 of them, and with them uncovered many of nature's secrets.

Robert Koch won the 1905 Nobel Prize for work on which disease, whose bacterium he spotted under his microscope?

Tuberculosis: Koch announced the discovery in Berlin on 24 March 1882, and the WHO marks that date every year as World TB Day.

Which Delft painter, baptised four days before van Leeuwenhoek, left a bankrupt estate the microscopist was appointed to manage?

Johannes Vermeer died in 1675 owing money to creditors, so his widow petitioned the court for relief, and van Leeuwenhoek was appointed trustee of the estate.

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 found the capillaries in the lungs in 1661, the link between arteries and veins that had eluded William Harvey.

Using an electron microscope, Scottish virologist June Almeida identified the first human example of which kind of virus?

Coronavirus: Almeida, a bus driver's daughter who left school at 16, helped name the group after the crown-like halo she saw around each particle.

On a compound microscope, what is the lens at the top of the tube called?

The eyepiece magnifies the image the objective has already projected into the tube, so the specimen is enlarged in two stages.

Manu Prakash's Foldscope, a microscope costing under a dollar in parts, is made mainly from what?

Paper: Prakash came up with it after seeing an expensive microscope at a research station in Thailand that everyone was afraid to use.

Diffraction limits ordinary light microscopes to roughly what resolving distance?

200 nanometres, about half the wavelength of light, is why structures as small as single proteins could never be made out with an ordinary light microscope.

What is placed between objective and cover slip to push numerical aperture as high as 1.5?

Immersion oil has a refractive index near 1.5, like glass, so light isn't bent away at the cover slip and the objective can gather more of it.

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

Ernst Abbe was first to define numerical aperture, and the resolution limit his 1873 equation set for light microscopes stood until the 2014 Chemistry Nobel laureates bypassed it.

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

August Köhler published the method in 1893 to improve photomicrographs: focusing the lamp's image at the condenser aperture instead of the specimen gives even lighting with no filament in view.

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

Frits Zernike's method turns invisible phase shifts in transparent samples into visible contrast, so biologists could study living specimens without the stains that once killed them.

Who patented the principle of the confocal microscope in 1957?

Marvin Minsky, better known as a founder of artificial intelligence, built his first confocal scanning microscope in 1955 while a Harvard Junior Fellow and filed the patent in 1957.

Which fluorescent stain do microscopists commonly use to label DNA?

DAPI binds to the A-T-rich stretches of DNA and glows blue under ultraviolet light, so it marks the nucleus while dyes in other colours mark the rest.

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 act as the lenses: a current-carrying coil bends a beam of electrons the way glass bends light, as Hans Busch calculated in 1926, though he never tested it himself.

Roughly what resolution can electron microscopes achieve?

0.1 nm is within reach because an electron's wavelength can be more than 100,000 times shorter than that of visible light, and shorter waves resolve finer detail.

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 the late 1930s?

Siemens took up the design in 1937 after a physician argued biologists could use it, and its first series-built machine went to the laboratories of IG Farben.

The 2017 Chemistry Nobel rewarded a way to image biomolecules in electron microscopes by first doing what to them?

Flash-freezing them: Jacques Dubochet cooled water so fast it set glassy instead of forming ice crystals, so the molecules kept their natural shape in the microscope's vacuum.

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

Stereoscan went on sale only after Charles Oatley had spent years trying to persuade electron microscope makers to take up his group's scanning microscope.

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

Gerd Binnig and Heinrich Rohrer built it at IBM's Zürich lab, and just five years later they shared the 1986 Physics Nobel for its design.

A scanning tunneling microscope senses a surface using what?

An extremely sharp conducting tip is scanned just above the surface; electrons tunnel across the gap, and changes in that current map the surface atom by atom.

IBM researchers spelled out 'IBM' by moving atoms of which element across nickel?

Xenon: in 1989 Don Eigler and Erhard Schweizer pushed 35 xenon atoms into place on a nickel crystal cooled to 4 kelvin, spelling out the letters IBM.

German pastor Johann Goeze first described which micro-animals in 1773, calling them 'little water bears'?

Tardigrades: in 2019 a capsule of them in a dried, dormant state rode the Israeli lander Beresheet, which crash-landed on the Moon.

In an atomic force microscope, the probe sits at the free end of what?

A small spring-like cantilever bends as the probe is scanned across the surface, and a laser bounced off its back onto a photodiode records each deflection.

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

Betzig, Moerner and Hell shared it, and Eric Betzig had quit Bell Labs before building his first prototype in the living room of his friend Harald Hess.

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, who built a submarine for the English navy around 1620, had a two-lens microscope in London by 1621.

Which famous diarist called Micrographia 'the most ingenious book that ever I read in my life'?

Samuel Pepys sat up in his chamber until two o'clock one night in January 1665 to keep reading it.

Camillo Golgi and Santiago Ramón y Cajal shared the 1906 Nobel Prize while disagreeing about the structure of what?

The nervous system: Cajal used Golgi's own black staining method to show nerves are separate units with gaps between them, while Golgi held they formed one continuous web.

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

Magnetic levitation: the first tunnelling unit, fitted with permanent magnets, floated over a superconducting lead bowl, while later microscopes rely on simpler suspensions or eddy-current damping.

The glowing green protein that lets microscopists watch otherwise invisible proteins at work was first found in which animal?

A jellyfish, Aequorea victoria, supplied the protein, and researchers now attach it to other proteins to watch processes such as brain development and the spread of cancer.

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

Toronto: Burton's students James Hillier and Albert Prebus built it in 1938, and Hillier went on to RCA, where he helped sell electron microscopes to research laboratories.

Which instrument did Calvin Goddard use to examine the bullets from Chicago's 1929 St. Valentine's Day Massacre?

A comparison microscope: two of the killers were dressed as police officers, but Goddard's tests showed the bullets hadn't come from police guns.

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.

Which children's author drew fungus spores under a microscope and sent a study to the Linnean Society?

Beatrix Potter was rebuffed by the director of Kew Gardens for being a woman and an amateur, so she wrote up her conclusions anyway. The Linnean Society apologised in 1997 for the way her research was handled.

Where do the vivid colours come from in electron microscope pictures of insects, pollen and bacteria?

Colour added afterwards is the source: an electron beam records only how strong a signal is at each point, which makes a picture in shades of grey. Tints are then chosen to help tell one structure from another.

NASA's Phoenix lander carried optical and atomic force microscopes to study the soil of which world?

Mars was where Phoenix touched down in 2008, the first landing in the planet's polar region. A robotic arm scooped up soil and delivered it to a sample wheel, which carried it under the microscopes.

Which pioneer of antiseptic surgery had a wine-trading father whose 1830 lens design transformed the microscope?

Joseph Lister grew up around microscopes because his father, working in spare time away from the wine business, found how to space lens elements so that colour fringes and blur both shrank.

Expansion microscopy swells specimens with polyacrylate, an absorbent polymer best known from which everyday product?

Diapers soak up liquid with the same polymer that MIT researchers used in 2015 to swell brain tissue to about 100 times its volume. Details too crowded to tell apart drift far enough apart for an ordinary microscope.

How does a slide of the printed letter 'e' appear when viewed through a compound light microscope?

Upside down and backwards is how everything looks, because the two-lens system flips the image. Push the slide left and the specimen drifts right, which is why beginners keep losing what they were looking at.

A stained blood film under a light microscope is the preferred test for which mosquito-borne disease?

Malaria parasites can be seen in the blood itself, and each of the main species has its own look, so a trained microscopist can name the one a patient is carrying.

Which famous camera brand began inside a microscope maker's factory in the German town of Wetzlar?

Leica is short for Leitz camera: the Leitz works made only microscopes at first, until its head of development, a keen amateur photographer, built a prototype camera shortly before the First World War.

What can a light microscope show that an electron microscope cannot, because of the vacuum inside?

Living creatures survive under a light microscope, so pond life can be watched swimming and feeding. Specimens for an electron microscope are usually fixed and dried, or frozen solid, before they go in.

Which part of a light microscope is the flat platform, often fitted with two clips, that holds the slide?

The stage has a hole in its centre so that light from below can pass up through the specimen. On many instruments two small dials glide the slide left, right, forward and back across it.

Which part beneath a light microscope's slide opens and closes to set the amount of light reaching the specimen?

The diaphragm works like the coloured ring of a human eye, which widens and narrows the pupil. Cameras use the same idea, under the same name, in the ring of blades that sets the opening of a lens.

Which lens sits below the slide on a light microscope and concentrates the lamp's light onto the specimen?

The condenser gathers the lamp's rays into a cone that lights up one small spot, then lets them spread out again to fill the objective above. Without it a tiny specimen would sit in gloom.

Which rotating part of a compound light microscope holds the objective lenses and swings each one into place?

The nosepiece is also called the turret or the revolver, and turning it is how a user changes magnification. A typical teaching instrument carries four objectives of different strengths on it.

When carrying a light microscope, one hand grips the arm while the other hand supports which part?

The base takes the weight so that the instrument stays upright on the way to the bench. Tip it over and the loose lenses at the top can slide out and fall.

With a 40x or 100x objective in place, which control should a microscope user turn to sharpen the image?

The fine focus knob moves the slide in tiny steps. At high power the lens sits so close to the glass that the bigger knob could drive one into the other, damaging the lens or cracking the slide.

How is the total magnification of a compound light microscope worked out from the powers of the two lenses?

Multiplying them gives the total, so a 10x lens at the top and a 40x objective make 400x. That is why swapping one objective for another can jump the view from 40x to 1,000x.

Before built-in lamps, what did student microscopes use beneath the slide to direct daylight up through the specimen?

A mirror is the simplest lighting a microscope can have, needing no power at all. Most later instruments carry a built-in halogen bulb or LEDs instead.

A magnifying glass and the simplest one-lens microscopes both enlarge objects with which shape of lens?

Convex lenses bulge outward and bend parallel rays of light inward until they meet at a spot. The same shape sits in a jeweller's loupe and in the viewing end of a telescope.

Stains are used in light microscopy because most unstained biological specimens are nearly what?

Transparent specimens let light straight through, so every part looks alike until dyes cling to some structures more than others. The catch is that staining usually kills whatever is on the slide.

Which term describes objective lenses that keep a specimen in focus when the user switches from one to another?

Parfocal objectives are matched so that the view stays clear from one to the next, with at most a small touch-up needed. True zoom lenses for photography are designed the same way.

When a student switches a light microscope to a higher-power objective, what happens to the area of slide in view?

It gets smaller in step with the power: an objective ten times stronger shows a circle one tenth as wide. That is why a lost specimen is easiest to find again by dropping back to the lowest power.

Which term describes enlarging a microscope image past the point where any new detail appears?

Empty magnification makes a picture bigger but no clearer, like zooming into a phone photo until it blurs. It begins once the finest detail the lenses can separate already matches the finest the eye can see.

Iodine solution dropped onto a thin slice of potato on a microscope slide turns which substance blue-black?

Starch traps iodine inside its coiled chains, which shifts the light the iodine absorbs and turns the pair an intense inky colour. Chemists use the trick the other way round too, as a signal that iodine is present.

In the Gram stain, bacteria with thick walls keep the first dye and appear which colour under a light microscope?

Purple marks a Gram-positive microbe, whose thick wall holds the first dye when alcohol is poured over it. Thin-walled Gram-negative ones wash clean and pick up a pink or red second dye instead.

Which instrument slices specimens into sections thin enough for light to pass through under a microscope?

A microtome can shave slices thin enough to section a human hair across its width. Before it existed, microscopists cut their plant and animal specimens by hand with razor blades.

Which type of low-power microscope uses two separate optical paths to give a three-dimensional view of whole objects?

Dissecting microscopes send a slightly different view to each eye, the way a pair of eyes judges depth. They suit solid objects, so watchmakers and circuit-board inspectors rely on them as well as biologists.

Which pond dweller, nicknamed the slipper animalcule, has long been a favourite specimen in school microscope lessons?

Paramecium owes the nickname to its shape, which a French microscopist compared to a slipper in 1718. It breeds so readily in a jar that its kind have been called the lab rats of their group.

Which vegetable's tissue-thin inner skin is peeled off as a classic first specimen for student microscopes?

Onion skin peels away in a sheet a single layer thick, so light passes straight through with no slicing needed. It also holds no green pigment, because a bulb stores energy instead of making it.

Which medical specialist diagnoses disease by studying thin stained slices of a patient's tissue under a microscope?

A pathologist gives the verdict on a biopsy: a small piece taken from the patient is processed, sliced and mounted on glass, then read at the microscope for signs of disease.

Insects and other insulating specimens are usually sputter-coated with which metal before scanning electron microscopy?

Gold gives electric charge a path to drain away to ground. Without such a skin the charge delivered by the beam builds up on the specimen and spoils the picture.

Which metal forms the hot filament in the electron gun of many electron microscopes?

Tungsten can be heated until electrons boil off it because it has a very high melting point. The same toughness made it the standard filament of the incandescent lamp.

Which structure did botanist Robert Brown name in 1831 after seeing an opaque spot in orchid tissue?

The nucleus had been seen and drawn by earlier microscopists, but it was Brown who named it, in a talk in London. He offered a second name as well, areola, which never caught on.

Geologists identify minerals in thin slices of rock with a petrographic microscope, which uses what kind of light?

Polarised light shows up optical properties that differ from mineral to mineral and change as a crystal is turned. Two filters set at right angles do the work, with the rock slice rotating between them.

A confocal microscope sharpens its images by blocking out-of-focus light with which simple feature?

A pinhole in front of the detector passes only light from the plane in focus. By capturing one thin layer after another at different depths, the instrument builds a 3D picture without ever cutting the specimen.

For light microscopy, tissue samples are most often embedded in a block of which material before slicing?

Paraffin wax soaks into the tissue once its water has been driven out, then sets firm enough for a blade to shave off slices thinner than a hair.

Haematoxylin is paired with which pink dye in the most widely used stain in medical diagnosis?

Eosin tints most of a tissue slice in shades of pink, while its partner turns the DNA-rich parts blue. Hospital labs know the pair simply as H&E.

Camillo Golgi's 'black reaction' makes tissue stand out under a light microscope by depositing a salt of which metal?

Silver settles in only a few of the tissue's units, seemingly at random, but fills those few completely. Each one then stands out whole and black against a clear background, delicate branches and all.

IBM's stop-motion film A Boy and His Atom was animated by nudging single molecules of which gas?

Carbon monoxide molecules were pushed one at a time across a sheet of copper and photographed frame by frame, magnified 100 million times. Guinness lists the one-minute result as the smallest stop-motion film.

In which German university town did Carl Zeiss open the 1846 workshop that grew into a famous microscope maker?

Jena was where Zeiss could open only after sitting a written exam and swearing an oath before the town authorities. He started with 100 talers borrowed from his brother, and the firm still carries his name.

Which camera and microscope maker has run the Small World photomicrography competition since 1975?

Nikon opens the contest to anyone with a light microscope, scientist or hobbyist, and later added a second prize for films and time-lapse. A single year has drawn entries from more than 80 countries.

Dennis Gabor won a Nobel Prize for which 3D imaging method, first devised around an electron microscope in 1947?

Holography came to Gabor while he was working for a British electrical firm, and his first version used electrons instead of visible light. The Nobel Prize followed in 1971.

Carl Zeiss learned his trade under a court instrument maker who built and repaired apparatus for which German writer?

Goethe was a customer of the workshop where the young Zeiss served his apprenticeship, and the tie went further: Zeiss's mother was related to the writer's wife.

Which tiny algae, housed in intricate shells of silica, did Charles Darwin praise as beautiful sights for a microscope?

Diatoms build their glassy cases with such regular pores and ribs that Darwin asked, in On the Origin of Species, whether they could have been made simply to be admired. He put their beauty down to symmetry of growth.

Which Rochester, New York firm, later famous for contact lenses, began making microscopes in 1876?

Bausch & Lomb began in 1853 as a small workshop run by a German-born optician and a cabinet maker who put up the money. By 1900 it was selling microscopes, binoculars and camera lenses.

Which French astronomer created the constellation Microscopium, one of several he named after scientific instruments?

Lacaille spent two years in the early 1750s charting the southern sky from the Cape of Good Hope and drew new constellations to fill its gaps. Microscopium's brightest stars are too faint to see from a light-polluted town.

Which philosopher, expelled from his Amsterdam synagogue, ground lenses for microscopes and telescopes to pay his way?

Baruch Spinoza polished lenses and built instruments both for income and out of scientific interest, while writing the philosophy that made his name. He kept a modest and frugal household on the work.

Which fixative do hospital labs most widely use to preserve tissue before it is sliced for the light microscope?

Formalin stops decay by cross-linking the proteins in a specimen, which locks its structures in place. The standard recipe is a buffered solution holding about four per cent formaldehyde.

George Papanicolaou's smear test, read under a microscope, screens for cancer of which part of the body?

The cervix is checked by collecting a small sample and examining it on a slide for abnormal shapes, before any cancer has had time to develop. The Greek doctor behind the test devised it in the 1920s.

Besides glass, knives made of which gemstone cut the ultra-thin sections needed for electron microscopy?

Diamond knives of gem quality shave the thinnest slices, which an electron beam has to be able to pass through. Industrial-grade stones handle hard specimens such as bone and teeth.

Which Greek letter is the symbol for micro-, the prefix in the unit used to size specimens under a microscope?

Mu stands for one millionth, so a micrometre is a millionth of a metre. The prefix comes from the Greek word for small, the same root that opens the word microscope.