High-Speed Optoelectronic Detector Front-End for Optical Coherence Tomography Applications

Abstract

The aim of this project is to develop a high-speed optoelectronic detector circuit for a novel optical coherence tomography (OCT) system. Trusted as the standard of care in ophthalmic diagnostics, OCT imaging procedures are advantageous over other imaging techniques due to being non-invasive while successfully producing a high-resolution retinal scan in minutes. Although current fields-of-view only capture 1/50th of the retina per scan, this novel high-speed OCT system would conduct a high-resolution, full retinal scan within 0.1 second. Key to achieving this benchmark is the middle stage of the OCT system — the optoelectronic detector circuit — bridging the optical source with the digital processing stage. Just as a translator must quickly and accurately convey the meaning of a message from one language to another, the detector circuit is responsible for converting a range of light wavelengths from a photodiode into a measurable digital voltage. This signal must be driven reliably — in spite of noise interference and attenuation — for the digital processing to receive the correct data, and thus, generate a high-resolution retinal scan. For this novel OCT system, the detector circuit must operate at low power, balance between the key tradeoff of high-speed and wide bandwidth, and preserve signal integrity throughout sub-stages which include a photodiode, transimpedance amplifier (TIA), and analog-to-digital converter (ADC).