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Proceedings Paper

Low cost optical polarization sensor
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Paper Abstract

Polarized light is a naturally occurring phenomenon that human vision does not discern, yet it can provide useful supplementary information from an image or optical system. Polarization detection can be implemented using hybrid sensors where additional polarizing material is mounted onto a standard sensor. However these types of sensor tend to be expensive, requiring extra manufacturing and materials. Presented is a low cost polarization sensor which is implemented using standard CMOS technology and manufacturing techniques, without the need for supplementary implants or optical layers. The polarization sensor is realised using a polarization grating, formed from a standard metal layer, above a CMOS sensor. To compensate for the loss of photons due to the polarization grating, a high dynamic range sensor is implemented using large, 110 micron photodiodes. The photosensor is used in a "light to frequency conversion pixel" where the photocurrent is converted to a digital square wave output with a frequency proportional to the photon flux density. A modulation depth of 10% is achieved. A rotary encoder application implementing the polarization sensor is discussed.

Paper Details

Date Published: 21 February 2007
PDF: 8 pages
Proc. SPIE 6501, Sensors, Cameras, and Systems for Scientific/Industrial Applications VIII, 65010R (21 February 2007); doi: 10.1117/12.700502
Show Author Affiliations
D. Patrick Baxter, STMicroelectronics (United Kingdom)
Jeffrey M. Raynor, STMicroelectronics (United Kingdom)
Jean-Luc Jaffard, STMicroelectronics (United Kingdom)
David Renshaw, The Univ. of Edinburgh (United Kingdom)

Published in SPIE Proceedings Vol. 6501:
Sensors, Cameras, and Systems for Scientific/Industrial Applications VIII
Morley M. Blouke, Editor(s)

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