Configurable Quadrant Photodetector, an Improved Position Sensitive Device (PSD)

R. Esper-Chaín, A. Medina Escuela, D. Fariña and J.R. Sendra

IEEE Sensors Journal, 16-1, 2016, 109 - 119 - DOI: 10.1109/JSEN.2015.2475597

Abstract: Abstract—Position sensitive detectors (PSD), used in high-end biotechnology, are based on optical sensors built over quadrant photodetectors or active pixel sensor. These devices are intended to measure slight movements of laser spots. Quadrant photodetectors (QPD) are, by far, the best approach in terms of resolution and noise, but requires complex & expensive x-y micropositioners to perform sensor alignment with the incoming laser spot. Active pixel sensors (APS) are more versatile devices, that can virtually align with the spot by means of device configuration. However, due to its intrisic digital nature, the SNR and resolutions are degraded in APS. In this article, a new type of device called configurable quadrant photodetector (CQPD) and its theory of operation is presented. This new device combines the analog operation of the QPD with the configurability of the APS, by means of combining photodetectors elements with analog switches in a matrix-shaped architecture. Finally, a prototype chip has been fabricated are presented.

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