A replaceable optical subsystem for a laser-based photoplethysmographic monitor. At least one laser light source (200) is located in an optical subsystem (110) that can be easily detached from the monitor (110). The optical subsystem is attached to the monitor with the aid of a listening element (170) and communicates with the monitor via a monitor connector (160). The patient cable and sensor system, for delivery of the signals to and from the tissue-under-test, attach to the optical subsystem via a sensor connector (150). Other embodiments are described and shown.
