Today I have posted a series (9 in total) of clips in which Christopher Soraghan gives us a breakdown of a piece of kit he developed (with Fiachra, Charles, Ray and myself) as part of his research. The complete system is a near infrared spectroscopy instrument capable of non-invasive brain activity monitoring. He used it as part of a biofeedback system for brain computer interfacing. The system consists essentially of a number of dual wavelength optical sources (LED-based) and some high quality sensitive detectors (APDs). In todays clip Chris shows us inside the detectors. These are Hammamatsu C54060-01 APDs. They are coupled to the subjects heads via optical guides (just a big fiber bundle) and these are then lined up with the APD detector.
You can find an overview of the complete system in the following paper: