Endoscopic system for simultaneous visual examination and electronic detection of fluorescence

Abstract

A sensitive parallel system for visual examination of a target area with simultaneous detection and measurement of fluorescent emission from the same region is described. This device, originally designed and constructed for bronchial cancer detection, alternates visual illumination and narrow band excitation radiation in conjunction with a synchronously shuttered PMT at frequencies above the visual flicker fusion threshold to provide parallel operation. The signal from the PMT is synchronously amplified using a lock‐in amplifier, the dc output of which is voltage‐to‐frequency converted and amplified to provide an audible tone whose frequency is proportional to the fluorescence sensed.