‘I did not foresee at all the social-media application, nor its impact on society': Inventor of the CMOS-based image sensor on how a technology designed to take photos in space has changed the way we view the world

Dr. Eric Fossum, the inventor of the CMOS-based image sensor, did not anticipate the profound impact his creation would have on society. Known as the 'camera-on-a-chip', this invention enables high-resolution cameras to fit in our pockets, revolutionizing photography and videography.

Initially, photography and videography relied on photographic film or Charge-Coupled Devices (CCDs). The Apollo 11 mission, however, utilized Hasselblad cameras - too heavy for the return journey - necessitating film development upon return. CCDs, the predecessors of Fossum's invention, detected photons using individual pixels that sent an electrical charge to a readout amplifier in a row-by-row arrangement. Although CCDs reduced weight and improved image quality over film, they consumed high power and generated heat.

Fossum's CMOS image sensors overcame these limitations by assigning each pixel its own local conversion circuit and amplifier, enabling simultaneous reading while significantly reducing energy consumption and heat generation. Today, CMOS image sensors power our smartphones, doorbells, self-driving cars, and even spacecraft heading to space.

Fossum's thoughts on the CMOS-based image sensor's societal impact are intriguing. He envisioned the technology becoming ubiquitous but was uncertain about its actual impact, particularly in social media, citizen journalism, law enforcement, and privacy. Despite these concerns, he acknowledges the potential for misuse of the technology.

Interestingly, Fossum's work at NASA's Jet Propulsion Laboratory (JPL) was somewhat unconventional, given JPL's primary focus on robotic space exploration. However, JPL engineers pioneered digital imaging technologies for space, such as the idea of 'mosaic' image capture using an array of pixels. JPL's advancements in digital imaging technology can be traced back to Eugene F. Lally, who proposed the concept in 1961.

Fossum's current research at Dartmouth focuses on the Quanta Image Sensor (QIS). Unlike CMOS image sensors, QIS can detect individual photons and count the number of photoelectrons at each pixel, enabling high accuracy in low-light conditions. The QIS concept, rooted in intra-pixel charge transfer, aims to create superior images one photon at a time. It is technology-agnostic, applicable to SPAD QIS, which offers larger pixels, higher power consumption, and advanced time-tagging capabilities.