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Molnar and Alumni win Best Paper Award

Thursday, September 28, 2017

Cornell Electrical and Computer Engineering Professor Alyosha (Al) Molnar and several former students recently received the 2017 IEEE Sensors Journal Best Paper Award for their paper, “A Polar Symmetric CMOS Image Sensor for Rotation Invariant Measurement.” His co-authors include Sriram Sivaramakrishnan, Ph.D. ’15, Changhyuk Lee, Ph.D. ’14, Ben Johnson, Ph.D. ’14.

The award recognizes the best paper published in the IEEE Sensors Journal during 2016, based on general quality, originality, contributions, subject matter and timeliness. It will be presented duing the IEEE SENSORS 2017 Conference Awards Presentation in Glasgow, Scotland in November.

Their paper presents a CMOS image sensor for efficient capture of polar symmetric imaging targets. The array uses circular photodiodes, arranged in concentric rings to capture, for example, diffraction patterns generated by optically probing a revolving MEMS device. The chip is designed with a vacant, central spot to facilitate the easy single-axis alignment of the probing illumination, target device, and detector. Imaging of high-speed rotation (>1 kfps) is made possible by dividing the array into multiple concentric bands with sectorwise addressing control.

In their paper, the group has introduced a global shutter pixel reset scheme that reduces the fixed pattern noise that arises from using variable wiring between a grid of circuits and a circular array of sensors. They have demonstrated the sensor's capability to measure the rotation angle with a precision of 32 μrad and the rotation rates up to 300 rpm, and have demonstrate the concept of a compact optical metrology system for continuous inertial sensor calibration by imaging the diffraction pattern created by a commercial MEMS accelerometer probed by a red laser shone through the axis of symmetry of the image sensor.

Molnar’s research group works primarily with integrated circuits for radio frequency applications, computational imaging and bioelectrical interfaces,  deploying a wide range of expertise, from signal processing algorithms to systems architecture to transistor-level circuits to opto-electronic device physics to wet biology and neurobiology. This broad range of interests is rooted in Molnar’s core expertise in radio communications circuits and sensory, and especially visual neuroscience. The group’s interdisciplinary research often reveals fundamental similarities across problems, and so spurs new interdisciplinary research in unexpected directions.

During graduate school, Molnar worked on an early, ultra-low-power radio transceiver for wireless sensor networks, after which he worked on dissecting the structure and function of neural circuits in the mammalian retina, using a combination of electrophysiological, anatomical and pharmacological techniques, well as analysis techniques drawn from his circuits background. In 2007, he joined Cornell as an assistant professor focusing on radio frequency integrated circuits, computational imaging and neural interfaces.

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