A photoelectric device designed to be applied externally to a portion of a limb (e.g., a fingertip, toe) for the transcutaneous measurement of blood volume using light detection during limb plethysmography. It is intended to be connected to a limb plethysmograph (not included), whereby volume changes are represented graphically to represent blood flow/pulse. It is designed for use during vascular function assessment in a limb (e.g., measurement of toe brachial pressure index). Although similar to a pulse oximeter probe, it is dedicated to limb plethysmography, and not capable of oxygen saturation measurements. This is a reusable device.