Next-Gen Image Sensor Delivers High-Quality, Low-Light Imaging

A new imaging technology has been developed that can capture and count single photons with resolution as high as one megapixel and as fast as thousands of frames per second. Called the Quanta Image Sensor, or QIS, this technology enables highly sensitive, high-quality, easy-to-manipulate digital imaging as well as computer vision and 3D sensing, even in low-light situations.

This is a sample photo taken with the 1-megapixel Quanta Image Sensor operating at 1040 frames per second, with total power consumption as low as 17 mW. It is a binary single-photon image, so if the pixel was hit by one or more photons, it is white; if not, it is black. The far-right figure shows how an image in gray scale was created by summing up eight frames of binary images taken continuously. This process is where the innovative image processing of the QIS can be applied. Courtesy of Jiaju Ma.

QIS is a third-generation solid-state image sensor technology that is compatible with baseline CMOS image sensor (CIS) technologies. QIS offers the same advantages as CIS in terms of pixel size, spatial resolution, dark current, quantum efficiency, readout speed and power dissipation. It is able to operate at room temperature with resolution of one megapixel. The device is implemented in a commercial stacked (3D) backside-illuminated CMOS image sensor process.

The QIS sensor incorporates “jots” — the Dartmouth College research team’s name for very small pixels that are sensitive enough to detect a single photon of light. The team developed jot devices with ultralow read noise for photon counting at room temperature without using electron avalanche gain. QIS performs ultrafast scanning of the jots, capturing data from every single photon.

Researchers demonstrated QIS’ ultralow dark current both at room temperature and in a heated environment (60 °C). The high-speed single-photon imaging was tested and 1040-fps readout speed was demonstrated at 1M (one megapixel, or one million pixels) jot resolution.

Professor Eric R. Fossum, inventor of the CMOS image sensor and co-inventor of the QIS, said that the QIS is built using a commercially accessible, inexpensive process and is compatible with today’s CMOS image sensor technology while being readily scalable for higher resolution.

“That way it’s easier for industry to adopt it and mass produce it,” he said.

While the current QIS resolution is one megapixel, the team’s goal is for the QIS to contain hundreds of millions to billions of jots, all scanned at a very fast rate, said researcher and co-inventor Jiaju Ma.

The researchers believe that this technology could meet the need for high-speed, high-resolution, accurate photon-counting imaging for scientific, space, security and low-light imaging as well as a range of other applications. The team has founded a startup, Gigajot Technology, to further develop and apply the QIS technology to a number of promising applications.

The research was published in Optica, a publication of OSA, The Optical Society (doi: 10.1364/OPTICA.4.001474).