Boston Chapter of the IEEE Photonics Society

Abstract:  Functional near-infrared spectroscopy (fNIRS) and diffuse correlation spectroscopy (DCS) have shown promise as non-invasive optical methods for cerebral functional imaging. Both approaches currently have limits to sensitivity in adults. Sensitivity can be improved using temporal discrimination, where the laser excitation is of short (~400ps) duration and the detector rejects early photons that have not penetrated into the brain while maintain high sensitivity to those that have. We report here the development of a novel Read-Out Integrated Circuit (ROIC) that integrates with a 32x32 Single-Photon Avalanche photo-Detector (SPAD) array that can be either silicon (Si, for visible to infra-red) in indium-phosphide (InP, to allow operation at 1064µm). The ROIC is designed to arm the SPADs in less than 500ps synchronous with the excitation pulse, keeping the total detection window as short as 3ns of arming to minimize sensitivity to dark events (thermal and discharge-related). The entire array can be operated at a frame rate of at least ~10MHz, giving a full “firemap” of which pixels have had events for each frame. Data is exfiltrated serially directly to an FPGA where it can be processed in real time. This presentation will include results of recent detector performance tests and phantom demonstrations using this powerful new tool.

Biography:  Dr. Jonathan M. Richardson is a member of the technical staff at MIT Lincoln Laboratory in the Advanced Imaging group. He holds a Ph.D. from Harvard University and has most recently worked in the areas of medical imaging and climate science.

Location:  MIT Lincoln Laboratory Forbes Road