Faster. Better. Cheaper. Those were the instructions of then NASA administrator, Daniel Goldin, regarding space missions of the 1990s. While not a mantra synonymous with success during that time, the programme did deliver one spectacular triumph. And, like freeze-dried food, memory foam mattresses and Speedo swimsuits, the technology is used every day on Earth, by millions of people.
In the early 90s, while working for NASA’s Jet Propulsion Laboratory in California, engineer Eric Fossum developed CMOS image sensors. CMOS sensors, or complementary metal oxide semiconductors, are the final evolution of the digital image sensors invented by George Smith and Michael Tompsett back in the 1970s. Smaller in size, these new sensors used much less power and were much cheaper to make than their predecessors.
“The CMOS sensor uses both the other winners’ inventions,” said Fossum. “We basically made a small charge coupled device, or CCD, inside every pixel. Part of that little CCD in each pixel is the photo sensor part, and that is the pinned photodiode.”
“This technology was invented when I was working on a problem for NASA at the Jet Propulsion Laboratory,” he said. “We wanted to shrink down the very large spacecraft cameras into a much smaller size, reducing the payload mass for future rocket launches. The smaller size would also have an impact on the amount of power needed from the spacecraft to run the camera, and even reduce the amount of radiation shielding needed to protect it.”
In addition to cutting costs, the sensors also proved tougher than CCD imagers against the high energy cosmic rays in space.
Recognising its potential here on Earth, as well as among the stars, Fossum set about commercialising his invention. Selling the idea to camera manufacturers, however, proved harder than he imagined. After months of rejection from industry, Fossum took matters into his own hands. Joining forces with Sabrina Kemeny, Fossum launched ‘Photobit Corporation’ mass produce the chips.
As well as being found in billions of digital cameras worldwide, CMOS sensors are now integrated into almost every aspect of modern life. They make up fingerprint recognition buttons on smartphones and are used in biometric passport booths for border control.
Despite their impact on global society, Fossum’s CMOS sensors have had surprisingly little influence outside the atmosphere.
“Because of the length of time taken to plan space missions, few scientists are willing to risk their careers on ‘new’ technologies,” Fossum explained. “As a result, the adoption rate of CMOS sensors has been much slower in space than it has here on Earth.” There are, he confirmed, just a handful of spacecraft out in the solar system, equipped with his invention.
Back here on Earth, Fossum encourages others to follow in his footsteps as an engineer and inventor. As an inducted member of the National Inventors Hall of Fame, he is a regular visitor of the organisation’s education initiative, Camp Invention. The week-long summer camp is open to elementary students across America, challenging them with hands-on STEM activities. Run by school teachers, the camp also gives educators new skills to take back to the classroom. Alongside meeting the young inventors at camp, Fossum and his wife involved with setting up new camps in their home state of New Hampshire.
“It is so important to be able to inspire the next generation of engineers,” he said. “Because who is going to be able to solve the world’s problems in the future?”
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