DEVICES FOR INTEGRATED MULTI-APERTURE IMAGING

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Orals Announcement

DEVICES FOR INTEGRATED MULTI-APERTURE IMAGING

Student:  Keith Fife
Adviser:  Abbas El Gamal

Date:     Wednesday, May 28, 2008
Time:     3:00 PM (Refreshments served at 2:30 PM)
Location: CISX 101 Auditorium

Abstract:

There has been significant development of image sensors over the last
decade with work on CCDs and CMOS-based devices. Several issues have
been addressed such as sensitivity, resolution, capture rate, dynamic
range, dark current, crosstalk, power consumption, manufacturability
and cost. One consistent limitation in conventional image sensors has
been that the sensing area is constrained to a regular array of
photosites used to recover an intensity distribution in the focal
plane of the imaging system. Although this is the most direct method
of image capture, there are both practical and fundamental issues that
limit the scalability or performance of these systems.

This research explores an alternative, multi-aperture approach to
imaging, whereby the integrated image sensor is partitioned into an
array of apertures, each with its own local subarray of pixels and
image-forming optics. A virtual image is focused a certain distance
above the sensor such that the apertures capture overlapping views of
the scene. The subimages are post-processed to obtain both a high
resolution 2D image and a depth map. A key feature of this design is
in the use of submicron pixels to obtain accurate depth measurements
derived from the localization of features within adjacent subarrays.
Other benefits include the ability to (i) image objects at close
proximity to the sensor without the need for objective optics, (ii)
achieve excellent color separation through a per-aperture color filter
array, (iii) relax the requirements on the camera objective optics,
and (iv) increase the tolerance to defective pixels. The
multi-aperture architecture is also highly scalable, making it
possible to increase pixel counts well beyond current levels.

Fabricated pixel sizes down to 0.5um pitch will be presented along
with a prototype multi-aperture image sensor, which comprises a 166x76
array of 16x16, 0.7um pixel, FT-CCD subarrays with local readout
circuit and per-column 10-bit ADCs fabricated in a 0.11um CMOS process
modified for buried channel charge transfer.

• Prof. Abbas El Gamal (Adviser, Dept of. EE)
• Prof. H.S. Philip Wong (Associate Adviser, Dept of. EE)
• Prof. Bruce Wooley (Reader, Dept of. EE)
• Prof. Mark Horowitz (Chair, Dept of. EE/Computer Science)

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