Thursday, August 07, 2008

Hemispherical 'electronic eye' - and some implications...

The BBC News website yesterday reported on the development of a camera with a hemispheric detection surface, rather than the traditional 2D array. The paper on which this article is based (in Nature - link) proposes that this new technology will enable devices with "...a wide field of view and low aberrations with simple, few-component imaging optics", including bio-inspired devices for prosthetics purposes, and biological systems monitoring. This figure from the paper gives a very nice overview of the construction and structural properties of the system. Note that the individual sensory detectors are the same shape throughout - it is the interconnections between them which are modified. Abstract:
The human eye is a remarkable imaging device, with many attractive design features. Prominent among these is a hemispherical detector geometry, similar to that found in many other biological systems, that enables a wide field of view and low aberrations with simple, few-component imaging optics. This type of configuration is extremely difficult to achieve using established optoelectronics technologies, owing to the intrinsically planar nature of the patterning, deposition, etching, materials growth and doping methods that exist for fabricating such systems. Here we report strategies that avoid these limitations, and implement them to yield high-performance, hemispherical electronic eye cameras based on single-crystalline silicon. The approach uses wafer-scale optoelectronics formed in unusual, two-dimensionally compressible configurations and elastomeric transfer elements capable of transforming the planar layouts in which the systems are initially fabricated into hemispherical geometries for their final implementation. In a general sense, these methods, taken together with our theoretical analyses of their associated mechanics, provide practical routes for integrating well-developed planar device technologies onto the surfaces of complex curvilinear objects, suitable for diverse applications that cannot be addressed by conventional means.
From the cognitive/developmental robotics point of view, this sort of sensory capability has (to my mind) some pretty useful implications. Given that the morphology of the robots concerned, and that would include the morphology of the sensory systems, take central importance in the development (or learning) that the robot may perform, then these more 'biologically plausible' shapes may allow better comparisons to be made between robotic agent models and animals. Furthermore, from the morphological computation point of view (e.g. here, and here), this sort of sensory morphology may remove the need for a layer of image pre-processing - motion parallax for example. As seen in flighted insects, the shape of the eye and arrangements of the individual visual detectors upon it remove the need for complex transformations when the insect is flying through an environment - an example of how morphology reduces 'computational load'. If effects similar to these can be taken advantage of in cognitive and developmental robotics research, then a greater understanding and functionality may be gained. The development of this type of camera may be an additional step in this direction.

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