Optimum detectors for artificial object recognition

Lead Research Organisation: University of St Andrews
Department Name: Physics and Astronomy

Abstract

Current digital cameras have a linear response and are only really suitable for simple picture imaging under controlled light conditions. In fact compared to human vision these cameras have two critical and debilitating limitations, a limited dynamic range and variability in object colour. The first of these limitations causes saturation when the dynamic range of a scene is larger than that of the camera. The second limitation is subtler and means that unlike human vision it is difficult to use colour information from linear cameras in artificial object recognition systems. Both these limitations can be overcome using pixels with a relatively narrow spectral response and an output that is proportional to the logarithm of the detected photocurrent. We intend to overcome these limitations by developing a new camera technology based upon organic photodiodes and a logarithmic response.

Publications

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Jansen Van Vuuren R (2010) Determining the absorption tolerance of single chromophore photodiodes for machine vision in Applied Physics Letters

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Jansen-Van Vuuren R (2013) Colour selective organic photodetectors utilizing ketocyanine-cored dendrimers in Journal of Materials Chemistry C

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Jansen-Van Vuuren R (2014) Tuning the optoelectronic properties of cyanine and ketocyanine dyes by incorporation of 9,9-di-n-propylfluorenylindolenine in Dyes and Pigments

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Levell JW (2010) A hybrid organic semiconductor/silicon photodiode for efficient ultraviolet photodetection. in Optics express

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Pandey A (2009) Effect of metal cathode reflectance on the exciton-dissociation efficiency in heterojunction organic solar cells in Applied Physics Letters

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Pandey AK (2010) Photo-rechargeable battery effect in first generation cationic-cyanine dendrimers. in Advanced materials (Deerfield Beach, Fla.)

 
Description The grant explored the use of organic semiconductors and related materials to make improved photodetectors. In particular we explored whether dendrimers could be used to make spectrally selective photodetectors. We demonstrated that this was possible and that such materials could emulate the eye response giving them the potential to improve colour recognition in machine vision. In addition we found a simple way of extending the spectral response of a silicon photodiode into the ultraviolet and observed a novel lgiht-rechargeabel battery effect.
Exploitation Route The materials could be taken forward by chemical companies, whilst the devices made from them are relevant to electronics, ICT and machine vision.
Sectors Chemicals,Digital/Communication/Information Technologies (including Software),Electronics