Thayer professor Eric Fossum -- the engineer and physicist who invented the CMOS image sensor used in nearly all cellphone and digital cameras, webcams, medical imaging and other applications -- joined with Thayer PhD candidate Jiaju Ma in developing pixels for the new Quanta Image Sensor (QIS)."
"Their new sensor has the capability to significantly enhance low-light sensitivity. This is particularly important in applications such as "security cameras, astronomy, or life science imaging (like seeing how cells react under a microscope), where there's only just a few photons," says Fossum. "When we build an image sensor, we build a chip that is also sensitive to these photons. We were able to build a new kind of pixel with a sensitivity so high we could see one electron above all the background noise."
"The new pixels are considerably smaller than regular pixels since they are designed to sense only one photon, but many more are placed on the sensor to capture the same amount of total photons from the image. "We'd like to have 1 billion pixels on the sensor and we'll still keep the sensor the same size," says Ma."
"We deliberately wanted to invent it in way that is almost completely compatible with today's CMOS image sensor technology so it's easy for industry to adopt it," says Fossum. Engineering its size is a step in that direction.
"The question was how to build this in a current, commercially accessible, not-too-expensive CMOS process." he says. "You use all the tricks you can think of. Being able to measure one electron is fundamental from a scientific point of view and we were able to do it without a 'Manhattan Project'." Other challenges his group is working on are in reading out a billion pixels hundreds or thousands of time each second without dissipating too much heat, and also in creating images from all the data that is collected.
