The humble image sensor. They are so ubiquitous these days that there are literally billions of them out there. Many of us rely on them either to create an income and to document family vacations or the daily goings on in our lives. But how many of us know how they actually work? How do they “see” light? Or colour?
In this video, Asianometry does a very deep dive into image sensors, taking a look at their initial origins and seeing how they’ve developed over time into the sensors we have at our disposal today. Whether they’re in our cameras, our phones or the webcams in our laptops, it’s impossible to escape them.
[Related reading: The World’s first digital camera, introduced by the man who invented it]
Despite digital cameras being a relatively modern invention, their story begins in 1889 when German physicist Heinrich Hertz (yes, that guy) realised that UV light knocked certain atoms out of their normal orbits. Physics could not explain this at the time, but in 1921, Albert Einstein put forth a theory that would explain it. He would go on to receive a Nobel Prize in physics for this work.
It took more than 40 years for these concepts to become solid-state image sensors. Developed by Willard S. Boyle and George E. Smith, the Charge-Coupled Devices (CCD) was cutting-edge technology at the time. By today’s standards, though, it’s extremely primitive. However, it didn’t stop the pair from finally also receiving a Nobel Prize for their work in 2009.
These days, Complementary metal–oxide–semiconductor (CMOS) sensors tend to rule the roost, especially in general cameras for photography and video. There are some specialist astrophotography and scientific cameras that use CCDs, but most DSLRs, mirrorless cameras and cinema cameras made in the last decade or so have been almost exclusively CMOS. Nikon actually used CCD sensors in their early cameras. A trend that ended with the Nikon D200 before they, too, switched to CMOS.
It’s fascinating to see how sensors work at their most basic level and how they’ve evolved from that very fundamental 1889 discovery all the way up to the modern high-tech image sensors we have today. Given what’s actually happening on an image sensor, it’s amazing that they manage to pack such massive capability into such tiny packages.
Have you ever thought about how your camera’s sensor works?
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