Coded Access Optical Sensor Boosts CMOS/CCD Performance

A camera technology dubbed Coded Access Optical Sensor (CAOS) now works in unison with CCD and CMOS camera sensors to extract previously unseen images.

The CCD sensor camera — a technology that earned its inventors a Nobel Prize in 2009 — and CMOS sensor camera, and dominate imaging applications from medicine to industrial testing and machine vision to astronomy. Now researchers from University College Cork, led by professor Nabeel Riza, have demonstrated a CAOS-CMOS design that combines the CAOS imager platform with a CMOS multipixel optical sensor.

Image captured by CAOS camera of an extreme contrast and brightness target. Courtesy of Nabeel Riza/Optics Express, a publication of The Optical Society (OSA).

Unlike current CCD and CMOS cameras, the CAOS camera exploits the extreme dynamic range of electronic wireless technology by engaging time-frequency coding of agile pixels in the image space combined with time-frequency domain decoding via electronic processing to extract the pixel light intensity information.

Riza and his team demonstrated a three-order (a factor of 1000) improvement in camera dynamic range over a commercial CMOS sensor camera when subjected to test targets that created extreme brightness, as well as extreme contrast (>82 dB) conditions.

In addition compared to prior cameras, the CAOS camera features exceptionally low noise interpixel crosstalk performance along with optical spectrum flexibility — such as from the UV to near-infrared range, and high speed imaging capabilities.

The experimental CAOS-CMOS camera comprised a digital micromirror device, a silicon point-photo-detector with a variable gain amplifier, and a silicon CMOS sensor with a maximum-rated 51.3-dB dynamic range. White light imaging of three different brightness simultaneously viewed targets not viewable with the CMOS sensor alone, demonstrating an 82.06 dB dynamic range.

Applications for the camera could include industrial machine vision, welding, laser analysis, automotive, night vision, surveillance and multispectral military systems. The research was published in Optics Express, a publication of The Optical Society (OSA).