Fundamental research has shown that it is possible to detect every incident photon using a silicon based image sensor. Is the time close, therefore, that we will all have high-sensitivity night-vision cameras in our mobile phones, built with single-photon resolution CMOS image sensors?

Affordable electronic imaging in still-picture and mobile phone cameras has made photographers of all of us. As a consequence, many of us know the disappointment of obtaining only grainy, diffuse pictures taken under low-light conditions, although our eyes still let us see the world sharp and clear. This situation will soon change, because silicon – the semiconductor on which today’s microelectronics industry is based – is also an excellent photodetector, allowing each incident photon to be sensed. Three main technical problems need to be solved to bring low-cost night-vision to the consumer market: (1) Ultra-low-noise, compact electronic circuits in each pixel for the detection of each photo-generated electron, (2) Optimized semiconductor processes derived from CMOS fabrication technologies contribute only insignificant dark-noise levels to the overall signal readout noise, (3) Novel image stabilization methods – using opto-mechanical, electronic or signal processing techniques – provide for sharp images, even when a camera is hand-held during long exposure times.

For each of these problem areas, practical solutions have recently been developed, and they are already finding their way into products: Megapixel CMOS image sensors with a readout noise of less than 2 electrons at room temperature and at video pixel rates (10 MHz) have been demonstrated; this has been achieved with meticulous system-level architecture employing massively parallel low-pass filtering and noise reduction for many pixels concurrently. CMOS derived image sensor (CIS) fabrication processes are being optimized for lower and lower dark currents; today, so-called “buried photodiodes” reach dark current levels corresponding to only a few thermally generated electrons per second in each pixel. Reliable and robust image stabilization techniques can already be found in many electronic imaging products, in particular in video and in still-picture cameras.

The conclusion is obvious: Low-cost night-vision with single-photon resolution is on its way into our electronic cameras. Watch this space!

More information on latest developments in electronic imaging will be presented and discussed at the EOS conference Frontiers in Electronic Imaging, held under the umbrella of the World of Photonics Congress, from 15 - 17 June, 2009.  More Information >>>