Intellect PlusOptical technology
85 cards. Each one is a 40-second story with a five-minute read behind it. Page 2 of 2.
The accidental blueprint: How a 19th-century iron tonic changed the history of documentationBefore digital scanners and copiers, the world relied on a simple, vibrant blue process. Invented by Sir John Herschel in 1842, the cyanotype used iron salts and sunlight to creat…
A French painter in Brazil may have named photography before anyone in EuropeHércules Florence, a French artist living in Campinas, Brazil, was experimenting with silver salts on paper by 1832 and called the result photographie in private notes apparently …
Polaroid sheets work because stretched plastic lines up iodine electronsThe polarising film in sunglasses and phone screens is a sheet of polyvinyl alcohol plastic laced with iodine. Stretching it during manufacture lines its long molecules up in one …
Most prisms are used to flip images, not to make rainbowsSplitting white light into a rainbow is the most famous thing a prism does, but it is not what prisms are mostly used for. Inside binoculars and single-lens reflex cameras, prisms…
Radio astronomy began with a Bell Labs engineer hunting for telephone staticIn 1932 Karl Jansky of Bell Telephone Laboratories was asked to track down static that might disturb radiotelephone calls. Besides near and distant thunderstorms, his rotating ant…
The word telescope was coined at a banquet for Galileo in 1611Galileo called his instrument a perspicillum. The name that stuck came in 1611 from Giovanni Demisiani, a mathematician of Greek origin, who proposed it at a banquet of Rome's Acc…
A theodolite measures angles so finely it can resolve seconds of arcThat telescope on a tripod you see at roadworks is a theodolite, and it is built to measure angles, not distances. Swivelling around two axes, it records exactly where it points b…
Michelson moved his light experiment out of Berlin because horses shook the groundIn 1881 Albert Michelson built an instrument to detect Earth's motion through space by comparing two beams of light. Central Berlin's horse traffic caused too much vibration, so h…
Strictly speaking, the laser should have been called a loserLaser stands for light amplification by stimulated emission of radiation. But a laser that makes its own light is really an oscillator, not an amplifier, so physicists have joked …
The word lens comes from the Latin for lentilA lens bulging on both sides looks a lot like a lentil, and that is exactly where the name comes from: lens was the Latin word for the legume. The object itself may be far older t…- Galileo called his microscope a little eye before a friend renamed itWhen Galileo presented a compound microscope to Rome's Accademia dei Lincei in 1625, he called it the occhiolino, or little eye. His fellow academician Giovanni Faber came up with…
The oldest manufactured mirrors were polished volcanic glass, some 8,000 years oldBefore glass and silver, people looked at themselves in obsidian, a natural volcanic glass polished to a shine. Examples from Çatalhöyük in Anatolia date to around 6000 BCE. For m…- Fibre optics on the 1969 Moon cameras were a classified secretWhen NASA sent television cameras to the Moon, their use of optical fibres was classified, and anyone handling the cameras had to be watched by someone with security clearance. Ju…
- Light microscopes hit a wall at about 200 nanometres, however much they magnifyYou can keep cranking up a light microscope's magnification, but past a certain point the picture just gets bigger and blurrier. Because visible light diffracts, details closer to…
Reflecting telescopes took over a century to catch on after Newton built oneIsaac Newton built a practical mirror telescope in 1668, avoiding the colour fringes that plagued lens telescopes. Yet his speculum metal mirrors were hard to make and performed p…- Early photographic film could only see blue lightUntreated silver halide crystals, the light-catching heart of photographic film, respond only to the blue end of the spectrum, so early photographs rendered some colours strangely…
Cut a hologram in half and each piece still shows the whole sceneTear a photograph in two and you get two halves of a picture. Split a hologram and each fragment still contains the entire scene, seen through a smaller window. That is because ev…
Lord Rayleigh found tarnished old glass let through more light than newIn 1886 Lord Rayleigh noticed something odd: slightly tarnished pieces of old glass transmitted more light than clean new ones. The dull film sat between air and glass in refracti…
Why roof-prism binoculars must be aligned 300 times more precisely than Porro onesThe two numbers stamped on binoculars, like 10×50, mean magnification and the width of the front lenses in millimetres. Hidden inside is a harder problem: flipping the upside-down…
From darkened room to phone: how the camera shrank over two centuriesEvery camera ever made, from a wooden box of 1839 to the one in your pocket, follows one recipe: a lens bends light into a sealed chamber, a shutter decides how long it stays, and…- The failed memory idea that became the eye of digital camerasIn 1969 two Bell Labs engineers were trying to build a new kind of computer memory based on magnetic bubbles. They realised a packet of electric charge could stand in for a bubble…
- A feather, some hairs and a CD: the story of the diffraction gratingTilt a CD under a lamp and rainbows slide across it. The disc's tightly packed spiral of data tracks splits white light into its colours, the same trick a Scottish mathematician s…
- The first portable digital camera weighed 8 pounds and took 23 seconds per pictureIn December 1975 a Kodak engineer named Steven Sasson pressed the button on a boxy prototype and waited 23 seconds while it wrote a black-and-white picture of 10,000 pixels onto c…
- Who invented the electron microscope? A patent office and a Nobel committee disagreeLight microscopes hit a wall at about 200 nanometres, because visible light waves are simply too long. Swapping light for electrons, whose wavelength can be over 100,000 times sho…
The surprising evolution from handheld stones to ear-hooking spectaclesBefore they rested on your nose, glasses were heavy spheres you had to hold over a page. It took centuries for eyewear to move from simple magnifying tools to the sophisticated, m…