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Efforts to capture visions beyond the range of the normal eye have long engaged scientists and engineers. By the mid-1880s George Eastman had improved upon celluloid and at the turn of the 20th century used it with his new camera, the Brownie. That boxy little phenomenon is still remembered by many adults today, even as digital cameras record the world around us by harnessing electrons. The discovery of X rays was only the first of many achievements leading to the development of picture-making devices that today support all manner of endeavors—in the military, medical, meteorological, computer technology, and space exploration communities. As the preceding pages make clear, images—microscopic, mundane, magnificent—affect us in all aspects of our lives.
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1900 |
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Kodak Brownie camera
Eastman introduces the Kodak Brownie camera. Named after popular children’s book characters, it sells for $1 and uses film that sells for 15¢ a roll. For the first time, photography is inexpensive and accessible to anyone who wants to take "snapshots." In the first year 150,000 cameras are sold, and many of the first owners are children. In the course of its long production life, the Brownie has more than 175 models; the last one is marketed as late as 1980 in England.
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1913 |
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Mammography research
Albert Solomon, a pathologist in Berlin, uses a conventional x-ray machine to produce images of 3,000 gross anatomic mastectomy specimens, observing black spots at the centers of breast carcinomas. Mammography, the resulting imaging, has been used since 1927 as a diagnostic tool in the early detection of breast cancer.
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1913 |
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Hot cathode x-ray tube invented
William David Coolidge invents the hot cathode x-ray tube, using a thermionic tube with a heated cathode electron emitter to replace the cold, or gas, tube. All modern x-ray tubes are of the thermionic type.
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1915 |
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The hydrophone developed
French professor and physicist Paul Langevin, working with Swiss physicist and engineer Constantin Chilowsky, develops the hydrophone, a high-frequency, ultrasonic echo-sounding device. The pioneering underwater sound technique is improved by the U.S. Navy and used during World War I in antisubmarine warfare as well as in locating icebergs. The work forms the basis for research and development into pulse-echo sonar (sound navigation and ranging), used on naval ships as well as ocean liners.
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1931-1933 |
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Electron microscope
Ernst Ruska, a German electrical engineer working with Max Kroll, constructs and builds an electron microscope, the first instrument to provide better definition than a light microscope. Electron microscopes can view objects as small as the diameter of an atom and can magnify objects one million times. (In 1986 Ruska is awarded half of the Nobel Prize in physics. The other half is divided between Heinrich Rohrer and Gerd Binnig for their work on the scanning tunneling microscope; see 1981.)
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1935 |
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First practical radar
British scientist Sir Robert Watson-Watt patents the first practical radar (for radio detection and ranging) system for meteorological applications. During World War II radar is successfully used in Great Britain to detect incoming aircraft and provide information to intercept bombers.
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1939 |
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Resonant-cavity magnetron developed
Henry Boot and John Randall, at the University of Birmingham in England, develop the resonant-cavity magnetron, which combines features of two devices, the magnetron and the klystron. The magnetron, capable of generating high-frequency radio pulses with large amounts of power, significantly advances radar technology and assists the Allies during World War II.
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1940s |
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Microwave radar systems
MIT’s Radiation Laboratory begins investigating the development of microwave radar systems, physical electronics, microwave physics, electromagnetic properties of matter, and microwave communication principles.
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1943 |
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Radar storm detection
The use of radar to detect storms begins. The U.S. Weather Radar Laboratory conducts research in the 1950s on Doppler radar, the change in frequency that occurs as a moving object nears or passes (an effect discovered for sound waves in 1842 by Austrian scientist Christian Doppler).
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1946 |
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Radar-equipped air traffic control
The Civil Aviation Authority unveils an experimental radar-equipped tower for control of civil flights. Air traffic controllers soon are able to track positions of aircraft on video displays for air traffic control and ground controlled approach to airports.
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1950s |
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Medical fluoroscopy and night vision
Russell Morgan, a professor of radiological science at Johns Hopkins University, Edward Chamberlain, a radiologist at Temple University, and John W. Coltman, a physicist and associate director of the Westinghouse Research Laboratories, perfect a method of screen intensification that reduces radiation exposure and improves fluoroscopic vision. Their image intensifier in fluoroscopy is now universally used in medical fluoroscopy and in military applications, including night vision.
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1950s |
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X-ray crystallography reveal helical structure of DNA
Rosalind Franklin uses x-ray crystallography to create crystal-clear x-ray photographs that reveal the basic helical structure of the DNA molecule.
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1950s |
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X-ray crystallography helps solve mystery
British chemists Max Perutz and Sir John Kendrew use x-ray crystallography to solve the structure of the oxygen-carrying proteins myoglobin and hemoglobin. They win the Nobel Prize in chemistry in 1962.
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1958 |
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Imaging device to detect tumors
Hal Anger invents a medical imaging device that enables physicians to detect tumors and make diagnoses by imaging gamma rays emitted by radioactive isotopes. Now the most common nuclear medicine imaging instrument worldwide, the camera uses photoelectron multiplier tubes closely packed behind a large scintillation crystal plate. The center of the scintillation is determined electronically by what is known as Anger logic.
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1959 |
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Ultrasound
Ian Donald, a professor working at the University of Glasgow’s Department of Midwifery, and his colleagues develop practical technology and applications for ultrasound as a diagnostic tool in obstetrics and gynecology. Ultrasound displays images on a screen of tissues or organs formed by the echoes of inaudible sound waves at high frequencies (20,000 or more vibrations per second) beamed into the body. The technique is used to look for tumors, analyze bone structure, or examine the health of an unborn baby.
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1960 |
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Radioisotopes for research, diagnosis, and treatment of disease
Powell Richards and Walter Tucker, and many colleagues at the Bureau of Engineering Research at the U.S. Department of Energy’s Brookhaven National Laboratory, invent a short halflife radionuclide generator that produces technetium-99m for use in diagnostic imaging procedures in nuclear medicine—a branch of medicine that uses radioisotopes for research, diagnosis, and treatment of disease. (Technetium-99m was discovered in 1939 by Emilio Segrè and Glenn Seaborg.)
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1960s |
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Optical lithography
Semiconductor manufacturing begins using optical lithography, an innovative technology using a highly specialized printing process that places intricate patterns onto silicon chips, or wafers. In the first stage an image containing the defining pattern is projected onto the silicon wafer, which is coated with a very thin layer of photosensitive material called "resist." The process is still used to manufacture integrated circuits and could continue to be used through the 100-nanometer generation of devices.
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1960s and 1970s |
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Space-based imaging begins
Space-based imaging gets under way throughout the 1960s as Earth-observing satellites begin to trace the planet’s topography. In 1968 astronauts on Apollo 7, the first piloted Apollo mission, conduct two scientific photographic sessions and transmit television pictures to the American public from inside the space capsule. In 1973 astronauts aboard Skylab, the first U.S. space station, conduct high-resolution photography of Earth using photographic remote-sensing systems mounted on the spacecraft as well as a Hasselblad handheld camera. Landsat satellites launched by NASA between 1972 and 1978 produce the first composite multispectral mosaic images of the 48 contiguous states. Landsat imagery provides information for monitoring agricultural productivity, water resources, urban growth, deforestation, and natural change.
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1962 |
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First PET transverse section instrument
Sy Rankowitz and James Robertson, working at Brookhaven National Laboratory, invent the first positron emission tomography (PET) transverse section instrument, using a ring of scintillation crystals surrounding the head. (The first application of positron imaging for medical diagnosis occurred in 1953, when Gordon Brownell and William Sweet at Massachusetts General Hospital imaged patients with suspected brain tumors.) The following year David Kuhl introduces radionuclide emission tomography leading to the first computerized axial tomography, as well as to refinements in PET scanning, which is used most often to detect cancer and to examine the effects of cancer therapy. A decade later single-photon emission tomography (SPECT) methods become capable of yielding accurate information similar to PET by incorporating mathematical algorithms by Thomas Budinger and Grant Gullberg of the University of California at Berkeley.
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1972 |
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MRI adapted for medical purposes
Using high-speed computers, magnetic resonance imaging (MRI) is adapted for medical purposes, offering better discrimination of soft tissue than x-ray CAT and is now widely used for noninvasive imaging throughout the body. Among the pioneers in the development of MRI are Felix Bloch and Edward Purcell (Nobel Prize winners in 1952), Paul Lauterbur, and Raymond Damadian.
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1972 |
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CAT scan
Engineer Godfrey Hounsfield of Britain’s EMI Laboratories and South African–born American physicist Allan Cormack of Tufts University develop the computerized axial tomography scanner, or CAT scan. 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. Used to guide the placement of instruments or treatments, CAT eventually becomes the primary tool for diagnosing brain and spinal disorders. (In 1979, Hounsfield and Cormack are awarded the Nobel Prize in physiology or medicine.)
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1981 |
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First scanning tunneling microscope
Gerd Binnig and Heinrich Rohrer, German physicists working at the IBM Research Laboratory in Zürich design and build the first scanning tunneling microscope (STM), with a small tungsten probe tip about one or two atoms wide. In 1986, Binnig, Cal Quate, and Christoph Gerber introduce the atomic force microscope (AFM), which is used in surface science, nanotechnology, polymer science, semiconductor materials processing, microbiology, and cellular biology. For invention of the STM Binnig and Rohrer share the 1986 Nobel Prize in physics with Ernst Ruska, who receives the award for his work on electron optics.
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1987 |
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Echo-planar imaging (EPI)
Echo-planar imaging (EPI) is used to perform real-time movie imaging of a single cardiac cycle. (Peter Mansfield of the School of Physics and Astronomy, University of Nottingham, first developed the EPI technique in 1977.) In 1993 the advent of functional MRI opens up new applications for EPI in mapping regions of the brain responsible for thought and motor control and provides early detection of acute stroke.
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1990 |
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Hubble Space Telescope
The Hubble Space Telescope goes into orbit on April 25, deployed by the crew of the Space Shuttle Discovery. A cooperative effort by the European Space Agency and NASA, Hubble is a space-based observatory first dreamt of in the 1940s. Stabilized in all three axes and equipped with special grapple fixtures and 76 handholds, the space telescope is intended to be regularly serviced by shuttle crews over the span of its 15-year design life.
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1990s–2000 |
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Spacecraft imaging instruments
NASA launches robotic spacecraft equipped with a variety of imaging instruments as part of a program of solar system exploration. Spacecraft have returned images not only from the planets but also from several of the moons of the gas giants.
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